How to use it
- Type a whole number (commas are fine, e.g. 1,024).
- Read the binary result, grouped in fours for readability.
- Follow the division table from bottom to top.
- Copy the result or switch to binary to decimal.
How to convert decimal to binary
Use repeated division by 2: divide the number by 2, write down the remainder (0 or 1), and continue with the quotient until it reaches 0. Then read the remainders from bottom to top.
Example: 45
| Division | Quotient | Remainder |
|---|---|---|
| 45 ÷ 2 | 22 | 1 |
| 22 ÷ 2 | 11 | 0 |
| 11 ÷ 2 | 5 | 1 |
| 5 ÷ 2 | 2 | 1 |
| 2 ÷ 2 | 1 | 0 |
| 1 ÷ 2 | 0 | 1 |
Reading up: 101101. Check: 32 + 8 + 4 + 1 = 45.
The converter shows this table for your number (the first 64 steps for very large values; the result itself is always exact) and the number of bits needed. Negative numbers are not converted here, because computers store them in different ways, such as two's complement.
Another quick method for small numbers: subtract the largest power of 2 that fits (32, 16, 8, 4, 2, 1) and mark a 1 for each power you used. To go to base 16 instead, use decimal to hex.
Frequently asked questions
What is 10 in binary?
What is 255 in binary?
11111111, eight ones.
How many bits does a number need?
The converter shows it. For example, numbers up to 255 fit in 8 bits, up to 65,535 in 16 bits.
Last updated: November 12, 2026