Hex to Decimal Converter

Convert hex to decimal — or decimal to hex, binary, and octal — with every field synced live.

A free online hex to decimal converter — type into any of the four fields below and the other three update instantly. Also works as a decimal to hex, hex to binary, and hex to octal converter. Uses arbitrary-precision math, so it stays exact even for values past 64-bit. Runs entirely in your browser.

Examples:

What is hex to decimal conversion?

Hexadecimal (base-16) uses 16 symbols — digits 0–9 and letters A–F — to represent numbers, while decimal (base-10) is the everyday counting system. Hex to decimal conversion translates a hex value into its ordinary numeric equivalent: each hex digit is multiplied by 16 raised to its position and the results are summed. Hex is common in programming, memory addresses, and color codes because it maps cleanly to binary (one hex digit = exactly 4 bits), but decimal is what people actually reason about — so converting between the two is one of the most common developer utility tasks.

Example: converting 1A2F to decimal

Take the hex value 1A2F. Working right to left, each digit is multiplied by 16 raised to its position: 1×16³ + 10×16² + 2×16¹ + 15×16⁰ = 4096 + 2560 + 32 + 15 = 6703. Type 1A2F into the Hexadecimal field above to see the same result instantly, along with its binary (1101000101111) and octal (15057) equivalents.

Why precision matters for large values

JavaScript's regular number type is only safe up to 2⁵³−1 (about 9 quadrillion) — past that, it silently rounds. That's a real problem for hex values like 64-bit memory addresses or hashes, which routinely exceed that limit. A hex value like FFFFFFFFFFFFFFFF is 18446744073709551615 in decimal — a naive converter would return the wrong number. This tool uses JavaScript's BigInt arbitrary-precision arithmetic throughout, so results stay exact no matter how large the input.

Beyond hex and decimal

The same value also has binary and octal representations, and all four fields stay in sync — enter a value in any one of them and the other three update immediately. This makes the tool useful for binary/hex conversions (common when reading bitmasks or flags) and octal conversions (still used for Unix file permissions like 0755), not just hex-to-decimal specifically.

Frequently asked questions

Type or paste a hexadecimal value into the Hexadecimal field — with or without a 0x prefix. The Decimal, Binary, and Octal fields update instantly with the same value in each base. There's no convert button; every field stays in sync as you type.

Type a decimal (base-10) number into the Decimal field. The Hexadecimal, Binary, and Octal fields update immediately with the equivalent value. It works the same way in either direction — decimal to hex or hex to decimal.

Multiply each hex digit by 16 raised to its position (counting from 0 on the right) and sum the results. For 1A: 1×16¹ + 10×16⁰ = 16 + 10 = 26 (A = 10 in hex). For 2F3: 2×16² + 15×16¹ + 3×16⁰ = 512 + 240 + 3 = 755.

Yes. The converter uses arbitrary-precision BigInt arithmetic, not JavaScript's regular Number type — so it stays exact for values well beyond 64-bit (18,446,744,073,709,551,615), where a naive converter would silently round off digits.

No. All conversion happens locally in your browser with JavaScript — nothing you type is ever sent anywhere.

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