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<!DOCTYPE html>
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<title>Number Base Converter — Binary, Hex, Octal | FreeDevTool</title>
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<h1>Number Base Converter</h1>
<p class="tool-description">
Convert between binary, decimal, hexadecimal, and octal number systems instantly. This free online number base converter supports radix conversion for any base from 2 to 36, with BigInt precision for arbitrarily large numbers. Explore positional notation across base-2, base-8, base-10, and base-16 numeral systems with grouped nibbles, bit-length display, and real-time input validation. All conversions happen client-side in your browser.
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<div class="last-updated">Last updated: May 2026 · Written by <a href="/about">Anees Ur Rehman</a>, full-stack developer</div>
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<div class="base-field" id="field-bin">
<div class="base-field-label">
<span class="base-field-name">Binary</span>
<span class="base-field-tag">Base 2</span>
<button class="copy-btn" onclick="copyField('bin')">Copy</button>
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<textarea id="input-bin" rows="2" placeholder="e.g. 11010110" spellcheck="false" oninput="convert('bin')"></textarea>
<div class="field-error" id="err-bin"></div>
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<div class="base-field" id="field-oct">
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<span class="base-field-name">Octal</span>
<span class="base-field-tag">Base 8</span>
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<span class="base-field-name">Decimal</span>
<span class="base-field-tag">Base 10</span>
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<div class="custom-base-row">
<label>Custom Base</label>
<input type="number" id="custom-radix" min="2" max="36" value="3" oninput="convert('custom')">
<input type="text" id="input-custom" placeholder="Enter value in custom base" spellcheck="false" oninput="convert('custom')">
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<div class="info-chip"><strong id="info-bits">—</strong> bits</div>
<div class="info-chip">Fits in <strong id="info-fit">—</strong></div>
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<div class="nibble-display" id="nibble-display" style="display:none;">
<div class="nibble-label">Binary (Grouped Nibbles)</div>
<div class="nibble-value" id="nibble-value" onclick="copyNibble()"></div>
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<p class="aeo-lead" style="font-size:16px;line-height:1.7;color:var(--text);max-width:760px;margin:24px auto 18px;padding:0 4px">
<strong>Number base conversion</strong> converts integers between binary (base 2), octal (base 8), decimal (base 10), and hexadecimal (base 16). Signed integers in binary use two's complement representation — the high bit indicates sign, and negative values are the bitwise inverse plus one. This <strong>free number base converter</strong> handles two's complement for negative numbers, missing from most online converters.
</p>
<section id="examples" style="max-width:760px;margin:24px auto 32px">
<h2 style="font-size:18px;margin-bottom:14px">Examples</h2>
<div style="background:var(--bg3);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:12px">
<strong style="display:block;color:var(--accent);font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:1px;margin-bottom:6px">Common conversions§§42 (decimal) = 101010 (binary) = 52 (octal) = 0x2A (hex)§§The same 6 bits viewed in 4 different bases.</strong>
</div>
<div style="background:var(--bg3);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:12px">
<strong style="display:block;color:var(--accent);font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:1px;margin-bottom:6px">Hex for memory addresses§§Memory addresses use hex because each hex digit is exactly 4 bits — 0xFF is 1 byte, 0xFFFF is 2 bytes. Easier to read than binary, more compact than decimal.</strong>
</div>
<div style="background:var(--bg3);border:1px solid var(--border);border-radius:var(--radius);padding:16px;margin-bottom:12px">
<strong style="display:block;color:var(--accent);font-family:var(--mono);font-size:11px;text-transform:uppercase;letter-spacing:1px;margin-bottom:6px">Two complement for negatives§§-5 in 8-bit two complement = 11111011 = 0xFB§§The high bit is the sign bit. To negate: invert all bits, add one. Used by every modern CPU to handle negative integers.</strong>
</div>
</section>
<aside class="founder-note" style="max-width:760px;margin:24px auto 32px;padding:20px 24px;background:rgba(0,208,132,0.05);border-left:3px solid var(--accent);border-radius:6px;font-size:14px;line-height:1.7;color:var(--text2)"><div style="font-family:var(--mono);font-size:11px;color:var(--accent);letter-spacing:1.5px;text-transform:uppercase;margin-bottom:10px;font-weight:600">💡 Why I built this</div><p style="margin:0 0 12px">I built this after debugging an embedded firmware bug where a signed 8-bit register read as 254 instead of -2. The conversion tool I was using only did unsigned, so I could not see what value the device was actually reporting. This converter supports two’s complement for negative numbers in binary and hex — the way actual hardware encodes signed integers. Critical for embedded, missing from most calculators.</p><p style="margin:0;font-size:13px;color:var(--text3)">— <a href="/about" style="color:var(--accent);text-decoration:none">Anees Ur Rehman</a>, full-stack developer</p></aside>
<section class="article-section">
<h2>Number bases explained — binary, octal, hex, decimal, and the math behind radix conversion</h2>
<p>If you have ever stared at <code>0xDEADBEEF</code> in a stack trace or typed <code>chmod 755</code> without thinking about it, you are already using positional number systems. This guide unpacks why programmers care about base-2, base-8, and base-16 — what each one buys you, how the conversion math actually works, what "two's complement" means in practice, and the language-specific syntax you need so the same number reads the same in JavaScript, Python, Go, Rust, and C.</p>
<h3>Positional notation — the one rule behind every base</h3>
<p>A number written in any base is a sum of digits multiplied by powers of that base. The decimal number 214 is <code>2×10² + 1×10¹ + 4×10⁰</code>. Take the same idea and swap 10 for any other base:</p>
<ul>
<li><strong>Binary 11010110</strong> = <code>1×2⁷ + 1×2⁶ + 0×2⁵ + 1×2⁴ + 0×2³ + 1×2² + 1×2¹ + 0×2⁰</code> = 128 + 64 + 16 + 4 + 2 = <strong>214</strong>.</li>
<li><strong>Octal 326</strong> = <code>3×8² + 2×8¹ + 6×8⁰</code> = 192 + 16 + 6 = <strong>214</strong>.</li>
<li><strong>Hexadecimal D6</strong> = <code>13×16¹ + 6×16⁰</code> = 208 + 6 = <strong>214</strong>.</li>
</ul>
<p>Notice that 214 has eight binary digits, three octal digits, three decimal digits, and two hex digits. Higher bases are denser — that is why programmers prefer hex over binary for byte-level work.</p>
<h3>Why each base matters</h3>
<table class="ref-table">
<thead><tr><th>Base</th><th>Digits</th><th>Where you see it</th></tr></thead>
<tbody>
<tr><td>Binary (2)</td><td>0, 1</td><td>Bit flags, hardware registers, network masks, low-level protocols.</td></tr>
<tr><td>Octal (8)</td><td>0–7</td><td>Unix file permissions (<code>chmod 755</code>), legacy PDP-11 systems, some C string escapes (<code>\137</code>).</td></tr>
<tr><td>Decimal (10)</td><td>0–9</td><td>Human-readable numbers, financial values, anything user-facing.</td></tr>
<tr><td>Hexadecimal (16)</td><td>0–9, A–F</td><td>Memory addresses, RGB color (<code>#FF5733</code>), MAC addresses, JWT signatures, hashes, byte dumps.</td></tr>
<tr><td>Base-32 / Base-36</td><td>0–9, A–V or A–Z</td><td>Crockford base32 in ULIDs, base36 in short-link IDs.</td></tr>
<tr><td>Base-58</td><td>Bitcoin alphabet (no 0, O, I, l)</td><td>Bitcoin addresses, Solana keys.</td></tr>
<tr><td>Base-64</td><td>A–Z, a–z, 0–9, +, /</td><td>Embedding binary in text (data URIs, basic auth, JWT body).</td></tr>
</tbody>
</table>
<p>Octal feels archaic, but every Unix admin uses it daily — <code>chmod 644 file</code> sets permissions to <code>110 100 100</code> in binary (rw- r-- r--).</p>
<h3>Two's complement — how computers represent negatives</h3>
<p>Computers store integers as fixed-width bit patterns. The trick to representing negative numbers is <strong>two's complement</strong>: the most-significant bit's place-value is negated. In an 8-bit signed integer, the leftmost bit's value is −128 instead of +128:</p>
<table class="ref-table">
<thead><tr><th>Binary (8 bits)</th><th>Unsigned</th><th>Signed (two's complement)</th></tr></thead>
<tbody>
<tr><td>00000000</td><td>0</td><td>0</td></tr>
<tr><td>00000001</td><td>1</td><td>1</td></tr>
<tr><td>01111111</td><td>127</td><td>127</td></tr>
<tr><td>10000000</td><td>128</td><td><strong>−128</strong></td></tr>
<tr><td>11111111</td><td>255</td><td><strong>−1</strong></td></tr>
</tbody>
</table>
<p>To negate a two's-complement number: invert every bit, then add 1. So +5 = <code>00000101</code>, invert → <code>11111010</code>, +1 → <code>11111011</code> = −5. The reason this encoding won is that addition and subtraction work the same circuit regardless of sign — no special case for negatives.</p>
<h3>Bitwise operators — what each one is for</h3>
<table class="ref-table">
<thead><tr><th>Operator</th><th>Effect</th><th>Use it for</th></tr></thead>
<tbody>
<tr><td><code>&</code> AND</td><td>1 only when both bits are 1</td><td>Mask: keep specific bits, drop the rest. <code>x & 0xFF</code> = low 8 bits.</td></tr>
<tr><td><code>|</code> OR</td><td>1 when either bit is 1</td><td>Set bits: <code>flags | READ</code> turns on READ.</td></tr>
<tr><td><code>^</code> XOR</td><td>1 when bits differ</td><td>Toggle bits, simple cipher round, parity check.</td></tr>
<tr><td><code>~</code> NOT</td><td>Flip every bit</td><td>Bitmask building: <code>~0xFF</code> clears low byte.</td></tr>
<tr><td><code><<</code> shift left</td><td>Multiply by 2 per shift</td><td>Build a single-bit mask: <code>1 << 7</code> = bit 7.</td></tr>
<tr><td><code>>></code> shift right (arithmetic)</td><td>Divide by 2; preserves sign bit</td><td>Sign-aware integer division by powers of 2.</td></tr>
<tr><td><code>>>></code> shift right (logical, JS)</td><td>Divide by 2; fills with 0</td><td>Treating the value as unsigned.</td></tr>
</tbody>
</table>
<h3>Bit width and overflow — the trap that bites every junior dev</h3>
<p>The same number can fit in 8, 16, 32, or 64 bits, with different limits at each width. The four widths you will see most:</p>
<table class="ref-table">
<thead><tr><th>Type</th><th>Bits</th><th>Unsigned range</th><th>Signed range</th></tr></thead>
<tbody>
<tr><td>byte / uint8</td><td>8</td><td>0 to 255</td><td>−128 to 127</td></tr>
<tr><td>short / int16</td><td>16</td><td>0 to 65 535</td><td>−32 768 to 32 767</td></tr>
<tr><td>int / int32</td><td>32</td><td>0 to 4 294 967 295</td><td>−2 147 483 648 to 2 147 483 647</td></tr>
<tr><td>long / int64</td><td>64</td><td>0 to 18.4 × 10¹⁸</td><td>−9.22 × 10¹⁸ to 9.22 × 10¹⁸</td></tr>
</tbody>
</table>
<p>The classic int32 overflow: <code>Math.pow(2, 31) - 1</code> in 32-bit signed wraps to −2 147 483 648 if you add 1. JavaScript number conversions to int32 (<code>x | 0</code>) hit this, and so does every <code>SELECT count(*)</code> on a table with billions of rows in a 32-bit-id schema. Use 64-bit types for anything that can grow.</p>
<h3>Number-base literals across 8 languages</h3>
<table class="ref-table">
<thead><tr><th>Language</th><th>Binary</th><th>Octal</th><th>Hex</th><th>Underscores</th></tr></thead>
<tbody>
<tr><td>JavaScript / TypeScript</td><td><code>0b1101</code></td><td><code>0o755</code></td><td><code>0xDEAD</code></td><td>Yes (<code>1_000_000</code>)</td></tr>
<tr><td>Python 3</td><td><code>0b1101</code></td><td><code>0o755</code></td><td><code>0xDEAD</code></td><td>Yes</td></tr>
<tr><td>Go</td><td><code>0b1101</code></td><td><code>0o755</code></td><td><code>0xDEAD</code></td><td>Yes (Go 1.13+)</td></tr>
<tr><td>Rust</td><td><code>0b1101</code></td><td><code>0o755</code></td><td><code>0xDEAD</code></td><td>Yes</td></tr>
<tr><td>Java 7+</td><td><code>0b1101</code></td><td><code>0755</code> (no o)</td><td><code>0xDEAD</code></td><td>Yes</td></tr>
<tr><td>C / C++14+</td><td><code>0b1101</code></td><td><code>0755</code></td><td><code>0xDEAD</code></td><td>Yes (C++14: <code>1'000'000</code>)</td></tr>
<tr><td>Ruby</td><td><code>0b1101</code></td><td><code>0755</code> or <code>0o755</code></td><td><code>0xDEAD</code></td><td>Yes</td></tr>
<tr><td>SQL (Postgres)</td><td><code>B'1101'</code></td><td>—</td><td><code>x'DEAD'</code></td><td>—</td></tr>
</tbody>
</table>
<p>The bare-leading-zero octal in C, C++, Java, Ruby (<code>0755</code>) is a historical hazard. <code>parseInt("08")</code> in old JavaScript returned 0 because of it; ES5 fixed that, but the lesson is to write <code>0o</code> explicitly.</p>
<h3>Common base-conversion mistakes</h3>
<ul>
<li><strong>Reading hex as decimal.</strong> <code>0x10</code> is <strong>16</strong>, not 10. Browser DevTools' "Memory" panel shows offsets in hex; mismatching it with decimal byte counts is a classic off-by-six bug.</li>
<li><strong>Forgetting that JavaScript bitwise ops truncate to int32.</strong> <code>0xFFFFFFFF | 0</code> is −1, not 4 294 967 295. For 64-bit arithmetic, use <code>BigInt</code>.</li>
<li><strong>Using <code>parseInt(str)</code> without a radix.</strong> Some older runtimes guess the base from a leading <code>0</code> or <code>0x</code>. Always pass the radix: <code>parseInt(str, 10)</code>, <code>parseInt(str, 16)</code>.</li>
<li><strong>Confusing chmod octal with permission bits.</strong> <code>chmod 755</code> = octal 755 = binary <code>111 101 101</code> = rwx r-x r-x. Do <em>not</em> write <code>chmod 0x755</code>.</li>
<li><strong>Mixing endian-ness.</strong> Network protocols are big-endian; x86 / ARM little-endian. When dumping a struct as hex bytes, the order on disk is the reverse of how you'd write the integer.</li>
<li><strong>Treating base-64 like a base.</strong> Base-64 is a binary-to-text encoding, not a positional numeral system. Padding (<code>=</code>) and 6-bit grouping have no analog in base-2/8/10/16.</li>
</ul>
<aside class="article-aside">
<strong>Authoritative references:</strong>
<ul>
<li><a href="https://en.cppreference.com/w/cpp/language/integer_literal" rel="noopener" target="_blank">cppreference — Integer literals (binary, octal, hex)</a></li>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Lexical_grammar#numeric_literals" rel="noopener" target="_blank">MDN — JavaScript numeric literals</a></li>
<li><a href="https://datatracker.ietf.org/doc/html/rfc4648" rel="noopener" target="_blank">RFC 4648 — base16, base32, base64 encodings</a></li>
<li><a href="https://man7.org/linux/man-pages/man1/chmod.1.html" rel="noopener" target="_blank">Linux chmod manpage — octal permission bits</a></li>
</ul>
</aside>
</section>
<!-- FAQ -->
<section class="faq-section">
<h2>Best number base converter for 2026 — what to compare</h2>
<p>Search results for "binary to decimal", "hex converter", "number base converter" return many tools but most fail on real-world numbers: they cap at 32-bit (silently truncating large values), they don't handle two's complement for negative numbers, they only support binary/octal/decimal/hex (skipping base32, base36, base58 for crypto), or they don't display the bit-length / grouped-nibble formatting needed for low-level debugging. Here's how the most-used base converters compare in 2026:</p>
<table class="ref-table">
<thead><tr><th>Tool</th><th>BigInt (no precision loss)</th><th>Bases supported</th><th>Two's complement</th><th>Bit length display</th><th>Cost</th></tr></thead>
<tbody>
<tr><td>FreeDevTool Number Base</td><td>Yes</td><td>2 through 36</td><td>Yes</td><td>Yes (with grouping)</td><td>Free</td></tr>
<tr><td>rapidtables.com/convert/number</td><td>32-bit limit</td><td>Bin/Oct/Dec/Hex</td><td>No</td><td>No</td><td>Free, ad-funded</td></tr>
<tr><td>binaryhexconverter.com</td><td>Limited</td><td>Bin/Oct/Dec/Hex</td><td>No</td><td>No</td><td>Free, ad-heavy</td></tr>
<tr><td>Windows Calculator (Programmer mode)</td><td>64-bit</td><td>Bin/Oct/Dec/Hex</td><td>Yes</td><td>Yes</td><td>Built-in</td></tr>
<tr><td>JavaScript <code>parseInt(str, base)</code></td><td>53-bit float</td><td>2-36</td><td>Manual</td><td>Manual</td><td>Built-in</td></tr>
<tr><td>Python <code>int(str, base)</code></td><td>Arbitrary precision</td><td>2-36</td><td>Manual</td><td>Manual</td><td>Built-in</td></tr>
</tbody>
</table>
<h3>How do I convert binary to decimal (or hex to decimal) online?</h3>
<p>Type your binary number in the binary input field — decimal, octal, and hex update instantly. The converter uses JavaScript BigInt internally so a 200-bit binary number converts without precision loss (unlike <code>parseInt</code> which silently rounds past 53 bits). For binary like <code>11010110</code>: type or paste the digits, see decimal <code>214</code>, hex <code>0xD6</code>, octal <code>0o326</code> instantly. For hex with prefix: type <code>0xDEADBEEF</code> or just <code>DEADBEEF</code> — both parse. The bit-length indicator shows the minimum bits required (8 bits for <code>0xD6</code>, 32 bits for <code>0xDEADBEEF</code>) which matters for fixed-width register debugging.</p>
<h3>What's the difference between binary, octal, decimal, hex, and base64?</h3>
<table class="ref-table">
<thead><tr><th>Base</th><th>Digits used</th><th>Common use</th></tr></thead>
<tbody>
<tr><td>Binary (2)</td><td>0, 1</td><td>Bitwise ops, low-level memory representation</td></tr>
<tr><td>Octal (8)</td><td>0-7</td><td>Unix file permissions (chmod 755)</td></tr>
<tr><td>Decimal (10)</td><td>0-9</td><td>Default human notation</td></tr>
<tr><td>Hexadecimal (16)</td><td>0-9, a-f</td><td>Color codes (#FF0000), memory addresses, byte representation</td></tr>
<tr><td>Base32 (Crockford)</td><td>0-9, a-z minus i, l, o, u</td><td>ULID, AWS S3 ARN, human-typeable IDs</td></tr>
<tr><td>Base36</td><td>0-9, a-z</td><td>Compact alphanumeric IDs, short URL slugs</td></tr>
<tr><td>Base58 (Bitcoin)</td><td>1-9, A-Z, a-z minus 0/O/I/l</td><td>Bitcoin/Monero addresses, short IDs</td></tr>
<tr><td>Base64</td><td>A-Z, a-z, 0-9, +, /</td><td>Binary-to-text encoding (use <a href="/base64-encoder">Base64 Encoder</a>)</td></tr>
</tbody>
</table>
<p>Decision rule: bitwise debugging → binary. Linux file perms → octal. Color/memory/byte → hex. Database short IDs → base36. Crypto / Bitcoin → base58. Binary blob in JSON → base64 (different operation, see <a href="/base64-encoder">Base64 Encoder</a>).</p>
<h3>Number base converter alternative to rapidtables.com — 4 reasons developers switched</h3>
<ol>
<li><strong>BigInt support — no 32-bit truncation.</strong> rapidtables silently truncates numbers above 2^32. This converter handles arbitrary-precision integers (200+ bits) for debugging large hashes or hex memory dumps.</li>
<li><strong>Two's complement for negative numbers.</strong> Type <code>-1</code> and see the two's-complement bit pattern at any bit-width (8/16/32/64) — useful for embedded systems and bit-flag debugging.</li>
<li><strong>Bases 2 through 36, not just 4.</strong> base32 (Crockford), base36 (short IDs), and any custom radix work in addition to binary/octal/decimal/hex.</li>
<li><strong>No ads, no popups.</strong> rapidtables and binaryhexconverter both inject ads. This page is browser-only and ad-free.</li>
</ol>
<p>Pair the number base converter with the <a href="/hex-to-rgb">Hex to RGB Converter</a> for color work, the <a href="/chmod-calculator">Chmod Calculator</a> for octal Unix permissions, the <a href="/byte-converter">Byte Converter</a> for KB/MB/GB conversion, and the <a href="/encoding-tools">Encoding Tools hub</a> for the broader transform toolkit.</p>
<h2>Frequently Asked Questions</h2>
<div class="faq-item open">
<div class="faq-q" onclick="toggleFaq(this)">
How do I convert binary to decimal?
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<div class="faq-a">
To convert binary to decimal, multiply each bit by 2 raised to the power of its position (starting from 0 on the right) and sum the results. For example, binary <code>1011</code> = (1 × 2³) + (0 × 2²) + (1 × 2¹) + (1 × 2&sup0;) = 8 + 0 + 2 + 1 = <strong>11</strong> in decimal. This positional notation principle applies to all numeral systems — the digit value is multiplied by the base raised to its position index.
</div>
</div>
<div class="faq-item">
<div class="faq-q" onclick="toggleFaq(this)">
What is hexadecimal and why is it used in programming?
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<div class="faq-a">
Hexadecimal (base-16) uses digits <code>0–9</code> and letters <code>A–F</code>. Each hex digit maps to exactly 4 binary bits (a nibble), making it a compact way to represent binary data. For example, <code>0xFF</code> = <code>11111111</code> in binary = <code>255</code> in decimal. Programmers use hex for memory addresses, color codes, byte values, and bitwise operations because it is far more readable than long binary strings while maintaining a direct relationship with the underlying binary system.
</div>
</div>
<div class="faq-item">
<div class="faq-q" onclick="toggleFaq(this)">
How do I convert between octal and binary?
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<div class="faq-a">
Each octal digit corresponds to exactly 3 binary bits. To convert octal to binary, replace each digit with its 3-bit binary equivalent: 0=<code>000</code>, 1=<code>001</code>, 2=<code>010</code>, 3=<code>011</code>, 4=<code>100</code>, 5=<code>101</code>, 6=<code>110</code>, 7=<code>111</code>. For example, octal <code>357</code> = <code>011 101 111</code> in binary. To go from binary to octal, group binary digits into sets of 3 from the right and convert each group to its octal equivalent.
</div>
</div>
<div class="faq-item">
<div class="faq-q" onclick="toggleFaq(this)">
What bases are commonly used in computer science?
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The most common bases are: <strong>Binary (base-2)</strong> — the fundamental language of computers, using 0s and 1s. <strong>Octal (base-8)</strong> — used in Unix file permissions and some legacy systems. <strong>Decimal (base-10)</strong> — the standard human numeral system. <strong>Hexadecimal (base-16)</strong> — widely used for memory addresses, color codes, and representing byte values compactly. Some systems also use base-36 (digits + entire alphabet) for compact ID encoding.
</div>
</div>
<div class="faq-item">
<div class="faq-q" onclick="toggleFaq(this)">
What is the difference between signed and unsigned binary numbers?
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<strong>Unsigned</strong> binary numbers represent only non-negative values — an 8-bit unsigned number ranges from 0 to 255. <strong>Signed</strong> binary uses the most significant bit (MSB) as a sign indicator. In two's complement (the most common signed representation), an 8-bit signed number ranges from −128 to 127. The binary value <code>11111111</code> is 255 when unsigned, but −1 in signed two's complement. Understanding this distinction is crucial for low-level programming and bitwise operations in languages like C and Rust.
</div>
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<script>
const BASES = {
bin: { radix: 2, id: 'input-bin', err: 'err-bin', field: 'field-bin', chars: /^[01]+$/ },
oct: { radix: 8, id: 'input-oct', err: 'err-oct', field: 'field-oct', chars: /^[0-7]+$/ },
dec: { radix: 10, id: 'input-dec', err: 'err-dec', field: 'field-dec', chars: /^[0-9]+$/ },
hex: { radix: 16, id: 'input-hex', err: 'err-hex', field: 'field-hex', chars: /^[0-9a-fA-F]+$/ }
};
function validCharsForBase(radix) {
const digits = '0123456789abcdefghijklmnopqrstuvwxyz'.slice(0, radix);
return new RegExp('^[' + digits + ']+$', 'i');
}
function bigIntToBase(n, radix) {
if (n === 0n) return '0';
const base = BigInt(radix);
const digits = '0123456789abcdefghijklmnopqrstuvwxyz';
let result = '';
let val = n < 0n ? -n : n;
while (val > 0n) {
result = digits[Number(val % base)] + result;
val = val / base;
}
return (n < 0n ? '-' : '') + result;
}
function parseBigInt(str, radix) {
str = str.trim().toLowerCase();
if (!str) return null;
const base = BigInt(radix);
const digits = '0123456789abcdefghijklmnopqrstuvwxyz';
let result = 0n;
for (let i = 0; i < str.length; i++) {
const d = digits.indexOf(str[i]);
if (d < 0 || d >= radix) return null;
result = result * base + BigInt(d);
}
return result;
}
function clearErrors() {
Object.keys(BASES).forEach(k => {
document.getElementById(BASES[k].err).style.display = 'none';
document.getElementById(BASES[k].id).classList.remove('invalid');
document.getElementById(BASES[k].field).classList.remove('has-error');
});
document.getElementById('err-custom').style.display = 'none';
document.getElementById('input-custom').classList.remove('invalid');
}
function showError(errId, inputId, fieldId, msg) {
const el = document.getElementById(errId);
el.textContent = '\u2717 ' + msg;
el.style.display = 'block';
if (inputId) document.getElementById(inputId).classList.add('invalid');
if (fieldId) document.getElementById(fieldId).classList.add('has-error');
}
function convert(source) {
clearErrors();
let value;
if (source === 'custom') {
const radix = parseInt(document.getElementById('custom-radix').value);
if (isNaN(radix) || radix < 2 || radix > 36) {
showError('err-custom', 'input-custom', null, 'Base must be between 2 and 36');
return;
}
const raw = document.getElementById('input-custom').value.trim();
if (!raw) { clearFields(); return; }
if (!validCharsForBase(radix).test(raw)) {
showError('err-custom', 'input-custom', null, 'Invalid characters for base ' + radix);
return;
}
value = parseBigInt(raw, radix);
if (value === null) {
showError('err-custom', 'input-custom', null, 'Invalid number');
return;
}
} else {
const b = BASES[source];
const raw = document.getElementById(b.id).value.trim();
if (!raw) { clearFields(); return; }
if (!b.chars.test(raw)) {
showError(b.err, b.id, b.field, 'Invalid characters for base ' + b.radix);
return;
}
value = parseBigInt(raw, b.radix);
if (value === null) {
showError(b.err, b.id, b.field, 'Invalid number');
return;
}
}
// Update all fields except source
Object.keys(BASES).forEach(k => {
if (k !== source) {
document.getElementById(BASES[k].id).value = bigIntToBase(value, BASES[k].radix).toUpperCase();
}
});
// Hex field: always uppercase
if (source === 'hex') {
// keep user input as-is
} else {
document.getElementById('input-hex').value = bigIntToBase(value, 16).toUpperCase();
}
// Update custom base
if (source !== 'custom') {
const radix = parseInt(document.getElementById('custom-radix').value);
if (!isNaN(radix) && radix >= 2 && radix <= 36) {
document.getElementById('input-custom').value = bigIntToBase(value, radix);
}
}
updateInfo(value);
updateNibbles(value);
}
function clearFields() {
Object.keys(BASES).forEach(k => {
document.getElementById(BASES[k].id).value = '';
});
document.getElementById('input-custom').value = '';
document.getElementById('info-bits').textContent = '\u2014';
document.getElementById('info-fit').textContent = '\u2014';
document.getElementById('nibble-display').style.display = 'none';
}
function updateInfo(value) {
if (value === null || value === undefined) return;