Data / Number / Computer Science Tools

Hex to Decimal Converter

Convert a hexadecimal number to its exact decimal value, handling arbitrarily large hex numbers correctly.

Enter a hexadecimal number below (with or without a 0x prefix) - this tool converts it to decimal exactly.

Hexadecimal Number

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For the reverse direction, see the Decimal to Hex Converter.

How Hex-to-Decimal Conversion Works

Each hex digit (0-9, A-F) represents a power of 16 based on its position - the decimal value is the sum of each digit's value multiplied by 16 raised to its position.

How to Use It

Enter a hex number, with or without a leading 0x.
The decimal equivalent appears instantly.

Limitations

This handles arbitrarily large hex integers accurately using BigInt, avoiding the precision loss that plain JavaScript number parsing would introduce for very long hex strings.

Worked Example

Convert 0x1F4 to decimal. Each position is a power of 16:

1 × 16² = 1 × 256 = 256
F (15) × 16¹ = 240
4 × 16⁰ = 4

256 + 240 + 4 = 500.

Common Conversions

Hex	Decimal	Where you see it
`FF`	255	Maximum of one byte, one colour channel
`100`	256	Number of values in a byte
`7FFFFFFF`	2,147,483,647	Largest signed 32-bit integer
`FFFF`	65,535	Largest 16-bit value, highest port number

Tips

Letters can be upper or lower case - ff and FF are the same.
Prefixes vary by context: 0x in code, # for colours, U+ for Unicode, h suffix in some assembly languages.
To read a colour like #1E56E3, convert each pair separately: 1E = 30, 56 = 86, E3 = 227.

Convert back with Decimal to Hex. For binary, use Number Base Converter.