How to convert decimal to octal
Divide the decimal number by 8 repeatedly, writing down each remainder. Read the remainders from the last to the first.
| Division | Quotient | Remainder |
|---|---|---|
| 156 ÷ 8 | 19 | 4 |
| 19 ÷ 8 | 2 | 3 |
| 2 ÷ 8 | 0 | 2 |
Reading the remainders upward gives 156₁₀ = 234₍8₎.
About the number systems
Decimal
Base 10 is the everyday number system with digits 0–9; each position is worth ten times the one to its right.
Octal
Base 8 uses digits 0–7. Each octal digit represents exactly three bits, which is why octal appears in Unix file permissions (e.g. 755).
Decimal to octal table
| Decimal | Octal |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 3 |
| 4 | 4 |
| 5 | 5 |
| 6 | 6 |
| 7 | 7 |
| 8 | 10 |
| 9 | 11 |
| 10 | 12 |
| 11 | 13 |
| 12 | 14 |
| 13 | 15 |
| 14 | 16 |
| 15 | 17 |
| 16 | 20 |
| 31 | 37 |
| 32 | 40 |
| 63 | 77 |
| 64 | 100 |
| 100 | 144 |
| 127 | 177 |
| 128 | 200 |
| 255 | 377 |
| 256 | 400 |
| 1000 | 1750 |
| 1024 | 2000 |
| 4096 | 10000 |
| 65535 | 177777 |
Frequently asked questions
How do I convert decimal to octal?
Divide the decimal number by 8 repeatedly, writing down each remainder. Read the remainders from the last to the first. Converting 156 to octal Division Quotient Remainder 156 ÷ 8 19 4 19 ÷ 8 2 3 2 ÷ 8 0 2 Reading the remainders upward gives 156₁₀ = 234 ₍8₎.
What is 255 in octal?
255 (decimal) = 377 in octal.
Can I convert very large numbers?
Yes. The converter uses exact big-integer arithmetic, so there is no rounding even for long inputs.