How to convert octal to hex by hand
Example 1: 777 in octal is 1FF in hex
Step 1: Octal to binary: write each digit as 3 bits
Because 8 = 2³, every octal digit maps to exactly 3 binary digits. Drop any leading zeros at the end.
| Octal digit | Value | 3 bits |
|---|---|---|
| 7 | 7 | 111 |
| 7 | 7 | 111 |
| 7 | 7 | 111 |
111 111 111 → 111111111
Step 2: Binary to hex: group the bits in 4s
Because 16 = 2⁴, every 4 bits make exactly one hex digit. Start from the right and pad the leftmost group with zeros if needed.
| 4-bit group | Value | Hex digit |
|---|---|---|
| 0001 | 1 | 1 |
| 1111 | 15 | F |
| 1111 | 15 | F |
0001 1111 1111 → 1FF
Example 2: 1750 in octal is 3E8 in hex
Step 1: Octal to binary: write each digit as 3 bits
Because 8 = 2³, every octal digit maps to exactly 3 binary digits. Drop any leading zeros at the end.
| Octal digit | Value | 3 bits |
|---|---|---|
| 1 | 1 | 001 |
| 7 | 7 | 111 |
| 5 | 5 | 101 |
| 0 | 0 | 000 |
001 111 101 000 → 1111101000
Step 2: Binary to hex: group the bits in 4s
Because 16 = 2⁴, every 4 bits make exactly one hex digit. Start from the right and pad the leftmost group with zeros if needed.
| 4-bit group | Value | Hex digit |
|---|---|---|
| 0011 | 3 | 3 |
| 1110 | 14 | E |
| 1000 | 8 | 8 |
0011 1110 1000 → 3E8
Octal to Hex conversion table
| Octal | Hex | Decimal |
|---|---|---|
| 0 | 0 | 0 |
| 1 | 1 | 1 |
| 2 | 2 | 2 |
| 3 | 3 | 3 |
| 4 | 4 | 4 |
| 5 | 5 | 5 |
| 6 | 6 | 6 |
| 7 | 7 | 7 |
| 10 | 8 | 8 |
| 11 | 9 | 9 |
| 12 | A | 10 |
| 13 | B | 11 |
| 14 | C | 12 |
| 15 | D | 13 |
| 16 | E | 14 |
| 17 | F | 15 |
| 20 | 10 | 16 |
| 40 | 20 | 32 |
| 100 | 40 | 64 |
| 144 | 64 | 100 |
| 200 | 80 | 128 |
| 377 | FF | 255 |
| 400 | 100 | 256 |
| 1000 | 200 | 512 |
| 1750 | 3E8 | 1000 |
| 2000 | 400 | 1024 |
Where this conversion comes up
- Turning a permission mode into hex for an API or log that uses hex: 0o777 is 0x1FF.
- Coursework that asks you to convert octal to hex without going through decimal.
Frequently asked questions
What is the quickest way to convert octal to hex by hand?
Write each octal digit as 3 bits, then regroup the bits in fours from the right and write each group as a hex digit.
Can I convert negative numbers?
Yes. Put a minus sign in front and it is kept in the result, for example -777 becomes -1FF. The converter does not produce two's complement.
Is there a limit on how big the number can be?
No practical limit. The conversion uses arbitrary precision integers, so long values stay exact. The step-by-step working is shown for numbers up to 24 digits.
Can I convert fractions?
Not with this tool. It converts whole octal numbers to whole hex numbers.
Other number converters
Going the other way? Use the Hex to Octal Converter. To see a number in every base at once, try the all-in-one number converter.