What is FF in decimal?

Hexadecimal FF equals 255 in decimal (the value 255, the largest number that fits in one byte).

Why are hexadecimal and decimal used?

Hexadecimal (base 16, digits 0–9 and A–F) writes each byte as exactly two characters, which is why it is used for colours (#FF8800), memory addresses and MAC addresses. Decimal (base 10) is the everyday number system.

Hexadecimal to Decimal

Efficiently convert hexadecimal numbers to decimal format for accurate numeric analysis, calculations, programming, or electronics projects where human-readable numbers are needed.

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Updated Sep 2026

In short

To convert hexadecimal to decimal, multiply each hexadecimal digit by 16 raised to its position (starting at 0 on the right) and add the results. For example, 2D = 2×16^1 + 13×16^0 = 45.

How it works

Hexadecimal counts in base 16, decimal counts in base 10. Converting means rewriting the same quantity with a different set of digits — the value never changes, only how it is written.

Number the digits from the right, starting at 0.
Multiply each digit by 16 raised to the power of its position.
Add the results — that total is the decimal value.

The reverse conversion is Decimal to Hexadecimal, which also handles every other base pair.

Examples

Worked examples, digit by digit:

10 (hexadecimal) = 1×16¹ + 0×16⁰ = 16 (decimal)
21 (hexadecimal) = 2×16¹ + 1×16⁰ = 33 (decimal)
FF (hexadecimal) = 15×16¹ + 15×16⁰ = 255 (decimal)

Common values in every base
Decimal	Binary	Octal	Hexadecimal
0	0	0	0
1	1	1	1
2	10	2	2
4	100	4	4
8	1000	10	8
10	1010	12	A
15	1111	17	F
16	10000	20	10
32	100000	40	20
64	1000000	100	40
100	1100100	144	64
255	11111111	377	FF

Hexadecimal to Decimal: frequently asked questions

How do I convert hexadecimal to decimal?: Multiply each hexadecimal digit by 16 raised to its position (starting at 0 on the right) and add the results. For example, 2D = 2×16^1 + 13×16^0 = 45. The converter above does this instantly for any value.
What is FF in decimal?: Hexadecimal FF equals 255 in decimal (the value 255, the largest number that fits in one byte).
Why are hexadecimal and decimal used?: Hexadecimal (base 16, digits 0–9 and A–F) writes each byte as exactly two characters, which is why it is used for colours (#FF8800), memory addresses and MAC addresses. Decimal (base 10) is the everyday number system.