Hex to Decimal Converter

By Suraj GiriUpdated 24 September 2026

Going the other way? Convert decimal back to hex →

How do you convert hex to decimal?

Hex to decimal conversion gives each digit the weight of its position, multiplies the digit by that weight, and adds the products together.

1. Number the positions from the right, starting at 0.
2. Give each position the weight 16ⁿ, so the rightmost digit is worth 1.
3. Multiply every digit by its weight and add the products.
4. The total is the decimal value: 9C = 156.

Hex to decimal is positional expansion with powers of 16; the number base converter takes any of the four bases and explains that method alongside repeated division.

Hexadecimal to Decimal Conversion Table

One hexadecimal digit equals exactly 4 bits (16 = 2⁴); one octal digit equals exactly 3 bits (8 = 2³). Hex and octal are therefore converted by grouping bits, and hex ↔ octal passes through binary. That is the whole method, so the table below is the only thing you need: every group of 4 bits has exactly one hex digit, and the mapping never changes. Binary writes values on the digit set 0, 1 with each place worth 2ⁿ, and a value marked 0b is binary; hex values are marked 0x.

Each base is defined by three things: which digits it uses, how a value is marked, and what each position is worth.

Worked Example: 9C to Decimal

One value, converted the long way so the working is visible. This is the same grid the converter shows when you turn on "show steps".

Number the positions from the right, starting at 0. Each position is worth 16 raised to that number, so the rightmost digit is worth 1, the next 16, the next 256, and so on up the value.

That turns 9C into 9 x 16^1 + C x 16^0, which adds up to 156. Digits that are 0 contribute nothing and can be skipped, but the position still counts — dropping a zero shifts every digit to its left and changes the value. This is the same expansion decimal itself uses; only the base in the weights differs.

Check it in reverse

The value returns unchanged. Convert 156 back and you get 9C, because a base change rewrites the digits without touching the quantity they stand for. That is the whole test: if the round trip differs, a digit was misread. To check it by hand, convert the decimal result back to hex and compare it with the number you started from.

Worked examples: hex to decimal

Each example gives the value first, then the working. Click a value to load it in the converter.

Every example above reverses exactly — divide the same value down to hex digits.

What About Padding, Fractions and Width?

Leading zeros and width

A number carries no leading zeros unless a width is fixed. 156 and 0156 are the same value, so the converter writes the short form. Fixed widths belong to bytes and registers, not to arithmetic. the number system conversion guide covers where width does matter.

Fractions and the point

Digits after a point convert by the same rule with negative powers, so the first place after the point is worth 1/10. Many fractions that end neatly in decimal repeat forever in binary, which is where rounding creeps in.

Negative values

A minus sign is kept in front of the digits: -9C converts to -156. Fixed-width binary encodes sign differently, using two's complement, and that is a separate rule from the base change itself.

How large a value can be

The method has no ceiling; each extra hexadecimal digit multiplies the range by 16. Practical limits come from the width a machine stores the value in, not from the conversion.

Hex to Decimal in Code

The same rule in one line. Both read the digits and return the decimal total.

Python: int('9C', 16)

JavaScript: parseInt('9C', 16)

Common Mistakes

• Reading the remainders top to bottom. They come out in reverse, so the digits land backwards.
• Using a digit the base does not have — an 8 in octal, or a 2 in binary. The value cannot be read at all.
• Grouping bits from the left. Groups are counted from the right, and the leftmost group is the one that gets padded.
• Treating the result as a character code. 41 is a number here, not the letter A.

Frequently Asked Questions

Related Conversions

• Hexadecimal also converts to binary by the same route — hex to bin nibble table.
• Hexadecimal also converts to ascii by the same route — hex to ASCII code lookup.
• Hexadecimal also converts to octal by the same route — hex to oct through a binary pivot.
• If your input is binary rather than hexadecimal, work out the decimal value of a binary number instead.
• If your input is octal rather than hexadecimal, convert octal to decimal instead.
• If your input is binary rather than hexadecimal, bin to hex nibble by nibble instead.

The rest of the family sits on the binary converter index.