Decimal (base 10)
Decimal (base 10) is the everyday number system, using the digits 0 through 9. It is the default base for almost all human-facing numbers — from prices to phone numbers to scientific measurements.
Decimal to Octal Converter
255 (dec) = 377 (oct)
Convert decimal numbers to octal numbers exactly, for any size. Convertitive parses your input as a BigInt — so 64-bit values, 256-bit hex strings, and even larger numbers round-trip without rounding. For quick reference: 255 dec = 377 oct, and 1024 dec = 2000 oct.
Quick
How to convert decimal numbers to octal numbers
Enter a value
Type a decimal integer in the From field. Allowed characters: 0 through 9.
Read the octal result
The To field updates as you type. For example, the decimal value 255 equals 377 in octal.
Copy or share
Use the copy button to grab the result. You can change either base from its dropdown without leaving the page.
Reference table
Fifty representative values. Every row is computed exactly by the same BigInt-based converter that powers the widget above.
| Decimal (dec) | Octal (oct) |
|---|---|
| 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 |
| 17 | 21 |
| 18 | 22 |
| 19 | 23 |
| 20 | 24 |
| 24 | 30 |
| 31 | 37 |
| 32 | 40 |
| 36 | 44 |
| 42 | 52 |
| 48 | 60 |
| 50 | 62 |
| 63 | 77 |
| 64 | 100 |
| 100 | 144 |
| 127 | 177 |
| 128 | 200 |
| 200 | 310 |
| 255 | 377 |
| 256 | 400 |
| 500 | 764 |
| 511 | 777 |
| 512 | 1000 |
| 1000 | 1750 |
| 1023 | 1777 |
| 1024 | 2000 |
| 2048 | 4000 |
| 4096 | 10000 |
| 8192 | 20000 |
| 16384 | 40000 |
| 32768 | 100000 |
| 65535 | 177777 |
| 65536 | 200000 |
| 1048576 | 4000000 |
Frequently asked questions
- How do I convert decimal numbers to octal numbers?
- Enter your decimal value above. Convertitive parses it as an arbitrary-precision integer and reformats it in octal. The conversion is exact for any size — there's no float rounding.
- What is 255 in octal?
- 255 (decimal) equals 377 in octal.
- Are negative numbers supported?
- Yes, with decimal. Two's-complement representations for fixed-width binary/hex are not supported here — the converter treats negative as a sign on the absolute value.
- What's the largest number I can convert?
- Any size. Convertitive uses JavaScript BigInt, which has no fixed upper bound — 256-bit hex strings, 512-bit and bigger all round-trip exactly.
- How many bits does the result take?
- An n-digit number in base 10 needs roughly 3.32 × n bits to store. The exact bit length equals ⌈log₂(value + 1)⌉.
- Is hex case-sensitive?
- Hexadecimal accepts letters in either case; this conversion doesn't involve hex.
- Are conversion factors exact?
- Yes. Base conversion is integer-to-integer; there are no factors, no rounding, no precision loss.
- Why would I convert decimal numbers to octal numbers?
- Octal still shows up in Unix file permissions (chmod 755) and in some embedded systems. Converting from decimal to octal is helpful when configuring file modes or working with legacy hardware documentation.
About decimal and octal
Octal (base 8)
Octal (base 8) uses the digits 0 through 7. Each octal digit represents exactly three bits, which is why octal was widely used on early minicomputers and is still the conventional notation for Unix file-permission masks (e.g. 755).