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Decimal to Octal Converter
Convert non-negative decimal integers to exact octal output with BigInt, strict whole-number validation, and an optional 0o prefix.
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Convert decimal integers to octal integers
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Detailed conversion guide
How to Convert Decimal to Octal
Repeatedly divide the decimal integer by eight and read the remainders from last to first. Decimal 493 produces 5, 5, and 7, so its octal form is 755.
The browser uses BigInt instead of floating-point Number arithmetic. Values larger than 9,007,199,254,740,991 stay exact rather than rounding silently.
| Input | Output | Meaning |
|---|---|---|
8 | 10 | base boundary |
63 | 77 | six bits |
255 | 377 | one byte |
493 | 755 | permission magnitude |
Decimal to Octal with BigInt
After strict decimal validation, construct a BigInt and call toString(8). Add 0o only as an output label, not as part of the magnitude.
if (!/^\d+$/.test(input)) throw new Error("Invalid decimal");
const octal = BigInt(input).toString(8);Whole Numbers, 0o Prefixes, and Unix Permissions
This is numeric conversion. Decimal 755 becomes octal 1363; it is not treated as a Unix permission string. Decimal 493 is the value of octal 755.
Negative numbers, fractions, exponential notation, commas, and prose are rejected. Spaces and underscores are visual digit separators only.
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