Hex to Decimal Converter
Type in either box — the other updates live, and the place-value working is shown underneath.
How Hex to Decimal Conversion Works
Hexadecimal is base 16: each place is worth sixteen times the place to its right, and the digits run 0–9 then A–F for the values ten to fifteen. Converting to decimal is just bookkeeping — multiply every digit by its place value and add. The places, from the right, are 160 = 1, 161 = 16, 162 = 256, 163 = 4,096, and so on.
Worked Example: 3F7 in Decimal
- Write out the places: 3 sits over 256, F sits over 16, 7 sits over 1.
- F is 15, so the sum is 3 × 256 + 15 × 16 + 7 × 1.
- That is 768 + 240 + 7 = 1,015.
The converter above prints this expansion for whatever you type, digit by digit, so the working is visible rather than hidden. It matters because hex is everywhere a computer shows you a compact number: web colours (#RRGGBB pairs are three hex bytes), MAC addresses, Unicode code points like U+1F600, error codes, and the memory addresses in a crash dump.
Working in the other bases as well? This shelf also has binary to hex, decimal to binary with its divide-by-2 steps written out, and the combined Binary Converter that shows all four bases — binary, decimal, hex and octal — at once.
Frequently Asked Questions
How do you convert hex to decimal?
Multiply each hex digit by its place value and add the results. Hex places are powers of 16 counting from the right: 1, 16, 256, 4,096… The letters are values too — A is 10, B is 11, C is 12, D is 13, E is 14 and F is 15. For 2A: 2 × 16 + 10 × 1 = 32 + 10 = 42.
What is FF in decimal?
FF in hex is 255 in decimal: F is worth 15, so FF = 15 × 16 + 15 × 1 = 240 + 15 = 255. It is the largest value two hex digits — one byte — can hold, which is why FF appears constantly in colour codes and memory dumps.
What is DEADBEEF in decimal?
DEADBEEF is 3,735,928,559 in decimal. It is a famous 'hexspeak' value programmers plant in uninitialised memory and crash dumps so the number is recognisable at a glance — the letters spell a word while still being valid hex.
What do the letters in hex mean?
Hexadecimal needs sixteen digit symbols, but ordinary digits only provide ten (0–9). So hex borrows the letters A to F for the values 10 to 15. A colour code like #FF5733 is three hex numbers in a row: FF (255) of red, 57 (87) of green and 33 (51) of blue.
How do you convert decimal back to hex?
Divide by 16 repeatedly and collect the remainders, converting any remainder of 10–15 into A–F, then read the remainders from last to first. For 42: 42 ÷ 16 = 2 remainder 10 (A), and 2 ÷ 16 = 0 remainder 2 — reading upwards gives 2A. Type a decimal number into the second box above and the hex appears as you type.
Is hex case-sensitive?
No. FF, ff and Ff are all the same value, 255. Uppercase is the common convention in most code and documentation, and this converter displays results in uppercase, but it accepts either case as input.
Does this converter handle long hex strings?
Yes. It uses exact integer arithmetic (BigInt) rather than floating point, so a long value such as FFFFFFFFFFFFFFFF converts to exactly 18446744073709551615 instead of a rounded approximation.
Is this hex to decimal converter free?
Yes. It is completely free with no signup required, and it runs entirely in your browser — the values you enter are never uploaded or stored.