Turn binary into octal by grouping the bits in threes, with any padding shown in the working.
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Type a binary number and this converter groups the bits in threes from the right, maps each group to one octal digit, and shows the padding it added. The conversion runs entirely in your browser, nothing leaves your device, and there is no sign-up or usage cap.
Octal has eight digits, and three bits can form exactly eight combinations, from 000 to 111. So the two systems lock together cleanly. Working from the right of the binary number, you cut it into groups of three, and each group of three bits becomes one octal digit. No division, no remainders, just grouping and reading off.
Take 101010. From the right it splits into 101 and 010. The group 101 is worth 5, and 010 is worth 2. The octal answer is 52. The mirror case, 101110, splits into 101 and 110, worth 5 and 6, giving 56.
The leftmost group often comes up short of three bits. When that happens, the tool pads it on the left with zeros until it reaches three, and the working shows those added zeros. Padding on the left never changes a value, in binary any more than writing 007 changes seven in decimal.
A full byte makes a tidy cross-check. The eight bits 11111111 group into 011, 111 and 111, which read as 3, 7 and 7. So a byte of all ones is 377 in octal, and the result also prints that this same value is 255 in decimal, so you can check the answer three ways at once.
That triple is worth remembering if you work with file permissions or old system output. A byte written in binary, octal and decimal should always agree, and when one form disagrees with the other two, you have found where a digit slipped.
Padding belongs to the first group only, and it is always shown. If you see zeros in the working that were not in your input, they sit at the front of the leftmost group, completing it to three bits. Nothing is ever padded in the middle or at the right.
Input is checked strictly. Binary uses only 0 and 1, so a stray digit or letter copied in by accident is named in the result with its position, rather than skipped or silently treated as a bit.
Whole numbers only. A part after a decimal point is flagged openly in the result, never dropped without a mention. Negative values are converted by size and labelled as sign and magnitude. Two’s complement is not applied.
Length is handled exactly. The converter uses arbitrary precision arithmetic, so a long run of bits converts group by group with no 53-bit ceiling rounding things along the way.
Starting from the right, split the binary number into groups of three bits. Pad the leftmost group with zeros if it has fewer than three. Then read each group as a number from 0 to 7 and write those digits in order.
It is 377. Grouped in threes from the right, the byte becomes 011, 111 and 111, worth 3, 7 and 7. The same value is 255 in decimal and FF in hex, which the result shows alongside.
Three bits make eight combinations, and octal has eight digits. Each group turns into exactly one octal digit, with nothing spare and nothing missing. Groups of two or four would not line up with octal at all.
No. The zeros are added at the far left of the first group only, where they carry no value. They exist so the first group has three bits like every other group, and the working shows them so you can account for every zero in the output.
Look at the decimal value printed in the same result. The input, the octal answer and the decimal figure all describe one number. Converting the octal back, by hand or with the octal converter, should land on your original bits.
The conversion stops, and the result names the bad digit along with its position in your input. A 2 cannot be a bit, so the tool reports it instead of guessing what you meant.
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