Free hex to decimal calculator
Convert hexadecimal numbers to decimal — enter any hex value to see the equivalent base-10 number, updated live, as you type.
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Hexadecimal to decimal conversion. Base-16 → base-10.
Results are estimates. Consult a professional.
How the hex-to-decimal calculator works
Hexadecimal (base-16) is a positional numeral system. Each digit's contribution to the total equals its face value multiplied by 16 raised to the power of its position, where positions are counted from zero starting at the rightmost digit. The letter digits A through F stand for the numeric values 10 through 15.
Worked example: 2F₁₆ and 1A3₁₆
Two conversions of increasing length to show the positional method: a two-digit hex value (2F) and a three-digit value (1A3).
Common hex values and their decimal equivalents
These values recur constantly in programming, color codes, and network addressing. Recognising them on sight eliminates the need for manual calculation in everyday work.
| Hex | Decimal | Common use |
|---|---|---|
| 0F | 15 | Maximum single hex digit |
| 10 | 16 | First two-digit hex number; 2⁴ |
| 1F | 31 | Lower 5 bits all set |
| 20 | 32 | Space character (ASCII); 2⁵ |
| 3C | 60 | Minutes / seconds in an hour |
| 64 | 100 | Full percentage; common opacity value |
| 7F | 127 | Max signed byte (two's complement) |
| 80 | 128 | Min negative signed byte; 2⁷ |
| FF | 255 | Max unsigned byte; full color channel |
| 100 | 256 | 2⁸; one byte overflow point |
| 400 | 1024 | 1 kibibyte (KiB); 2¹⁰ |
| FFFF | 65535 | Max 16-bit unsigned integer |
Source: standard computing reference values. ASCII table per ANSI X3.4-1986.
Tips for hex-to-decimal conversion
With practice, common hex values become instantly recognisable. Until then, these techniques keep manual conversion accurate and fast.
- Write positions under each digit — Label each digit with its position (0 at the right) before multiplying. This prevents the most common error: miscounting positions.
- Substitute letters first — Replace A–F with 10–15 before doing any arithmetic. Mixing letter and numeric representations mid-calculation leads to mistakes.
- Use 16¹ = 16, 16² = 256, 16³ = 4096 — Memorise these three powers and you can handle any value up to 0xFFFF (65,535) from memory.
- Break long strings into byte pairs — A 6-digit hex string like #1A2B3C splits naturally into 1A, 2B, 3C — each pair converts independently to a decimal value 0–255.
- Verify with the nibble method — Convert each hex digit to its 4-bit binary nibble, concatenate all nibbles, then evaluate the binary number. Both routes should give the same decimal.
Accuracy and limitations
The positional calculation is mathematically exact for non-negative integers of any length. For very large hex values (more than 13 hex digits, exceeding 2⁵³ − 1 in JavaScript), precision may be lost in environments using 64-bit floating-point arithmetic. Use a BigInt-based implementation when working with cryptographic hashes, UUIDs, or other large identifiers.
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