★ MATH · NUMBER SYSTEMS · CONVERTERS
Hex FF is octal 377. Convert hexadecimal to octal and octal back to hexadecimal through binary grouping, with every step shown and the full hex-to-binary table.
Hexadecimal and octal do not convert digit by digit, because their bases do not line up. Both convert cleanly through binary: hex digits become 4 bits each, octal digits become 3 bits each, and regrouping the bits gives the answer.
Hex FF to octal 377, worked in full: each hex digit becomes four bits, so F becomes 1111 and FF becomes 11111111. Pad on the left with zeros until the bit count is a multiple of three — 11111111 is already eight bits, so pad to nine: 011111111. Regroup in threes from the right: 011 111 111. Read each group as an octal digit: 011 is 3, 111 is 7, 111 is 7, giving 377. The reverse is the mirror image: octal 777 becomes three bits per digit, 111 111 111, padded to a multiple of four, 0001 1111 1111, regrouped in fours, 0001 is 1, 1111 is F, 1111 is F, giving hex 1FF. Hex 1A follows the same path: 0001 1010, padded to 000011010, regrouped as 011 010, which is octal 32. Hex FF00: 1111 1111 0000 0000, padded to 00111111100000000? No — counted properly, FF00 is sixteen bits, padded to eighteen: 00 1111 1111 0000 0000, regrouped in threes as 001 111 111 100 000 000, which is octal 177400. The padding rule is the whole trick: pad hex-to-octal to a multiple of three, and octal-to-hex to a multiple of four, always on the left, and never drop a leading group just because it starts with zero until the final answer is read.
| Hex digit | Binary (4 bits) | Decimal |
|---|---|---|
| 0 | 0000 | 0 |
| 1 | 0001 | 1 |
| 2 | 0010 | 2 |
| 3 | 0011 | 3 |
| 4 | 0100 | 4 |
| 5 | 0101 | 5 |
| 6 | 0110 | 6 |
| 7 | 0111 | 7 |
| 8 | 1000 | 8 |
| 9 | 1001 | 9 |
| A | 1010 | 10 |
| B | 1011 | 11 |
| C | 1100 | 12 |
| D | 1101 | 13 |
| E | 1110 | 14 |
| F | 1111 | 15 |
| Output | Formula | What it means |
|---|---|---|
| Hex FF to octal | FF → 11111111 → 011 111 111 | Octal 377 at the default. |
| Hex 1A to octal | 1A → 0001 1010 → 011 010 | Octal 32. |
| Hex FF00 to octal | FF00 → 16 bits, padded to 18 → 001 111 111 100 000 000 | Octal 177400. |
| Octal 777 to hex | 777 → 111 111 111 → 0001 1111 1111 | Hex 1FF. |
| Padding rule | Pad left to a multiple of 3 (to octal) or 4 (to hex) | Padding on the left never changes the value; padding on the right would. |
The conversion is exact mathematics, not an approximation: any finite hex value converts to exactly one octal value and back, with no rounding anywhere. The limits are practical, not mathematical: very long inputs are still exact but hard to read, leading zeros in the input are ignored in the output (hex 00FF and FF give the same 377), and this page converts integers only — fractional hex and octal values need a separate binary-point treatment. Case does not matter: ff, FF, and Ff are the same value.
Bright Side Kit. "Hex to Octal Converter: Two-Way Hex and Octal Calculator" https://brightoolbox.com/hex-to-octal/ Accessed October 24, 2026.Octal 377. FF in binary is 11111111, regrouped in threes as 011 111 111, which reads as 377.
Octal 32. 1A in binary is 0001 1010, regrouped as 011 010, which reads as 32.
Octal 177400. FF00 in binary is sixteen bits, padded to eighteen and regrouped as 001 111 111 100 000.
Hex 1FF. 777 in binary is 111 111 111, regrouped in fours as 0001 1111 1111, which reads as 1FF.
Because hex digits are 4 bits and octal digits are 3 bits, so no digit maps to a digit directly. Binary is the common language: convert to bits, regroup, and read the answer.
No. Octal digits are 0–7 only, so entering 8 or 9 is an error. Hex digits are 0–9 and A–F, so G is also an error.
No. FF, ff, and Ff are the same value, and the converter accepts all of them.