Octal to Binary
Octal to binary converts one octal number, including a fractional part, with a three-bit expansion for each digit.
All input digits are converted. No fractional-place cutoff, rounding or truncation is applied.
Calculation steps
Frequently asked questions
How do I convert octal to binary?
Enter one octal number and select Convert to binary. Each octal digit expands to three binary bits. Keep the point between the same integer and fractional parts, then join the groups. Open Calculation steps to see the expansion of every digit in your input.
Does this octal to binary converter accept fractions?
Yes. For example, 75.54 becomes 111101.1011. The digits 7 and 5 before the point expand to 111 and 101. After the point, 5 and 4 expand to 101 and 100. Joining them gives 111101.101100; removing trailing fractional zeros gives the same value, 111101.1011.
Why are some zeros removed?
Leading zeros before the integer digits and trailing zeros after the fractional digits do not change the numeric value, so the displayed result omits them. Zeros inside the number stay in place. An all-zero input produces 0. This is a numeric conversion, not a fixed-width binary display.
How many fractional bits are kept?
All fractional octal digits are expanded. Each digit contributes three bits before trailing-zero normalization. A finite octal fraction always has a finite binary representation, so there is no rounding or fractional-place cutoff.
Can I use spaces, a prefix or a negative value?
Yes. Whitespace groups a single value and is removed: 7 5.5 4 means 75.54, not multiple numbers. An optional leading plus or minus sign and optional 0o prefix are accepted. A leading or trailing point is accepted if at least one digit is present. A negative result uses a minus sign; it is not a fixed-width two's-complement word.
What input is rejected and what is the limit?
Use octal digits 0–7. Digits 8 and 9, commas, exponent notation, binary or hexadecimal prefixes and multiple points are rejected. Invalid input clears the previous result. The limit is one number per run, at most 1,000 octal digits and 10,000 total input characters including whitespace.
Is this the same as converting octal into text?
No. This page changes the numeric representation of the entire value. It does not interpret octal codes as letters or file bytes. For the reverse direction use Binary to Octal. For a decimal result use Octal to Decimal. For decimal input use Decimal to Octal.
Do I need an account or upload anything?
No. Conversion and copying run locally in the browser. The tool does not transmit your input. There is no batch mode or saved conversion history.
For an octal number converted directly to hexadecimal, use Octal to Hex.