Decimal to Hexadecimal Converter

How to Convert Decimal to Hex

To convert a decimal number to hexadecimal manually, follow these steps:

1. Divide the decimal number by 16
2. Record the remainder (0-15, where 10-15 become A-F)
3. Divide the quotient by 16 again
4. Repeat until the quotient is 0
5. Read the remainders in reverse order

Example: Convert 255 to hex:

• 255 ÷ 16 = 15 remainder 15 (F)
• 15 ÷ 16 = 0 remainder 15 (F)
• Result: FF (reading remainders in reverse)

Converting decimal fractions to hex

Type a point to convert a fraction. The whole part converts by repeated division as usual; the fraction part converts by repeated multiplication: multiply by 16, take the whole-number part of the product as the next digit, and carry on with what is left. 255.5 becomes FF.8.

A decimal fraction ends in hex only when its denominator, in lowest terms, is a power of 2. Everything else repeats forever: 0.1 is 0.1(9), where the digits in brackets repeat. That is why 0.1 cannot be stored exactly in a binary floating-point number. The converter shows the repeating block and cuts long results rather than rounding them.

Negative decimal to hex (two's complement)

A minus sign converts like any other number: -255 is -FF in hex. Inside a computer there is no minus sign, so negative integers are stored in two's complement at a fixed width: write the magnitude in binary at that width, invert every bit, and add 1. For -5 at 8 bits: 00000101, inverted 11111010, plus 1 gives 11111011 (0xFB). Enter a negative number above to see it at every width that fits.

Going the other way, or at a custom width, use the two's complement calculator.

Code Examples

const decimal = 255;
const hex = decimal.toString(16); // "ff"
const hexUpper = decimal.toString(16).toUpperCase(); // "FF"
const padded = decimal.toString(16).padStart(4, '0'); // "00ff"

Frequently Asked Questions

Related Tools