What is 377 octal in decimal?

377 in octal (base 8) equals 255 in decimal (base 10), which is 255 in decimal.

How do I convert octal to decimal by hand?

Multiply each octal digit by 8 raised to its position (starting at 0 on the right) and add the results. For 377: 3×8^2 + 7×8^1 + 7×8^0 = 255.

Is this exact for very large numbers?

Yes. The converter uses big-integer (BigInt) arithmetic in your browser, so even very long octal values convert to decimal with no rounding or precision loss.

Which characters are valid in octal?

Base-8 octal uses the digits 0–7. Spaces, underscores and an optional 0x/0b/0o prefix are ignored; any other character is flagged as invalid.

Octal to Decimal Converter

Convert a octal (base 8) number to decimal (base 10) instantly. As an example, 377 = 255. It runs entirely in your browser.

Octal value

Decimal result

Base	This number
Binary (base 2)	`—`
Octal (base 8)	`—`
Decimal (base 10)	`—`
Hexadecimal (base 16)	`—`

How to convert octal to decimal

Each digit of a octal number carries a weight that is a power of 8. Multiply every digit by 8 raised to its position (counting from 0 on the right) and add the results to get the decimal value:

3 × 8^2 + 7 × 8^1 + 7 × 8^0 = 255

Worked example: 377 in decimal

Reading 377 as base 8: 3 × 8² (= 192) + 7 × 8¹ (= 56) + 7 × 8⁰ (= 7) = 255 in decimal, which is 255 in decimal.

More octal-to-decimal examples: 12 = 10, 20 = 16, 100 = 64.

Binary, octal, decimal & hexadecimal reference table

Decimal	Binary	Octal	Hex
1	`1`	`1`	`1`
2	`10`	`2`	`2`
4	`100`	`4`	`4`
8	`1000`	`10`	`8`
10	`1010`	`12`	`A`
15	`1111`	`17`	`F`
16	`10000`	`20`	`10`
32	`100000`	`40`	`20`
64	`1000000`	`100`	`40`
100	`1100100`	`144`	`64`
128	`10000000`	`200`	`80`
255	`11111111`	`377`	`FF`
256	`100000000`	`400`	`100`
1024	`10000000000`	`2000`	`400`

About octal and decimal

Octal: Octal is base-8, using digits 0–7. Each octal digit maps to exactly three bits, which is why it appears in Unix file-permission modes such as 755.

Decimal: Decimal is base-10, the everyday number system using digits 0–9.

Frequently asked questions

What is 377 octal in decimal?: 377 in octal (base 8) equals 255 in decimal (base 10), which is 255 in decimal.
How do I convert octal to decimal by hand?: Multiply each octal digit by 8 raised to its position (starting at 0 on the right) and add the results. For 377: 3×8^2 + 7×8^1 + 7×8^0 = 255.
Is this exact for very large numbers?: Yes. The converter uses big-integer (BigInt) arithmetic in your browser, so even very long octal values convert to decimal with no rounding or precision loss.
Which characters are valid in octal?: Base-8 octal uses the digits 0–7. Spaces, underscores and an optional 0x/0b/0o prefix are ignored; any other character is flagged as invalid.

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