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Octal to Decimal Converter

Input
Output (Decimal)
Go To Full Number Base Converter

Convert octal integers (base 8) into standard decimal values (base 10). This variant defaults to batch mode, letting you paste multiple octal numbers separated by newlines to see the decimal translations instantly side-by-side.

Supported octal formats

The converter limits input to standard octal characters (0-7). You can include 0o prefixes, and the tool will safely ignore spaces or underscores in the text. Signed integers are supported by appending a leading + or -.

Error handling

Each line is calculated individually. If a line contains invalid characters—such as digits 8 or 9, letters, or decimals—that specific line outputs an inline error message while the rest of your batch finishes perfectly.

This allows you to convert extremely large octal strings without floating-point approximations or 64-bit maximum bounds.

Frequently Asked Questions

Yes. Use a leading minus sign (−) or plus sign (+). The sign is preserved in the decimal output.

Yes. This variant runs in batch mode by default: paste one octal integer per line and get one decimal result per line.

Yes. Inputs like 0o755 are accepted in this variant.

Yes. Spaces and underscores are ignored, so values like 7_55 or 0o7 55 work.

Octal maps cleanly to binary (each octal digit = 3 bits), and it’s commonly used for Unix-style file permissions.

Try one of our format-specific converters below

Full Number Base Converter tool

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