Octal to Hex Converter
Convert octal to hexadecimal instantly with exact integer conversion. Enter any valid base-8 number to get its uppercase hex value, binary bridge, digit counts, verified examples, and conversion tables.
What Is an Octal to Hex Converter?
An octal to hex converter changes a value from the octal number system (base 8) into the equivalent hexadecimal number system (base 16).
Octal uses digits 0 through 7. Hexadecimal uses digits 0 through 9 plus letters A through F for values 10 through 15.
Both systems have a direct relationship with binary. One octal digit equals exactly three binary bits, while one hexadecimal digit equals exactly four binary bits. That makes binary a convenient bridge between octal and hex.
Octal — Base 8
Every digit corresponds to one 3-bit binary group.
Hexadecimal — Base 16
Every hex digit corresponds to one 4-bit binary group.
How to Use the Octal to Hex Converter
Type a value such as 57. Only digits 0 through 7 are valid.
BinaryCon calculates the exact hexadecimal equivalent and displays A–F in uppercase.
The tool also shows how the octal value maps to binary before being regrouped into hexadecimal.
The result card reports the number of octal digits, hexadecimal digits, and significant binary bits.
Use the result in code, electronics, system work, coursework, or another BinaryCon converter.
How Octal to Hex Conversion Works
A convenient manual method is to convert each octal digit into three binary bits, combine those bits, regroup the complete binary value from the right into groups of four, and translate each 4-bit group into one hexadecimal digit.
Combined binary → groups of 4 bits
4-bit groups → hexadecimal digits
Worked Example: Convert Octal 57 to Hex
Start with octal 57₈.
7 → 111 Join the groups: 101111 Pad on the left to make complete 4-bit groups: 0010 1111 Convert each group to hex: 0010 → 2
1111 → F Therefore: 57₈ = 2F₁₆
Example: Convert Octal 377 to Hex
7 → 111
7 → 111 Combined binary: 011111111 Remove insignificant leading zero: 11111111 Group into four: 1111 1111 Convert: 1111 → F
1111 → F Therefore: 377₈ = FF₁₆ Both are decimal 255.
Octal to Hex Reference Table
| Octal | Hex | Decimal |
|---|---|---|
0 | 0 | 0 |
7 | 7 | 7 |
10 | 8 | 8 |
12 | A | 10 |
17 | F | 15 |
20 | 10 | 16 |
37 | 1F | 31 |
40 | 20 | 32 |
55 | 2D | 45 |
77 | 3F | 63 |
100 | 40 | 64 |
177 | 7F | 127 |
200 | 80 | 128 |
377 | FF | 255 |
400 | 100 | 256 |
777 | 1FF | 511 |
1000 | 200 | 512 |
Octal to Binary Mapping
| Octal | Binary |
|---|---|
| 0 | 000 |
| 1 | 001 |
| 2 | 010 |
| 3 | 011 |
| 4 | 100 |
| 5 | 101 |
| 6 | 110 |
| 7 | 111 |
Binary to Hex Mapping
| Binary | Hex | Binary | Hex |
|---|---|---|---|
0000 | 0 | 1000 | 8 |
0001 | 1 | 1001 | 9 |
0010 | 2 | 1010 | A |
0011 | 3 | 1011 | B |
0100 | 4 | 1100 | C |
0101 | 5 | 1101 | D |
0110 | 6 | 1110 | E |
0111 | 7 | 1111 | F |
Why Octal 12 Equals Hex A
Octal 12 means one group of eight plus two:
Why Octal 777 Equals Hex 1FF
Octal 777 represents decimal 511.
Can Octal Be Converted Directly to Hex?
Yes mathematically, but the easiest manual technique normally uses binary as an intermediate because both bases have exact binary group sizes.
Another valid method is:
Both paths produce the same result. BinaryCon calculates the exact integer value directly while also showing the binary bridge because it is especially useful for understanding why the conversion works.
Why Leading Zero Padding Does Not Change the Value
When regrouping binary bits from 3-bit octal groups into 4-bit hexadecimal groups, zeros may need to be added on the far left.
For example:
Those added leading zeros do not change the integer value. They only create complete groups for hexadecimal conversion.
Where Octal to Hex Conversion Is Useful
Programming
Values from octal literals, permissions, or legacy code may be easier to inspect or reuse in hexadecimal form.
Low-level debugging
Hex is widely used in debuggers, memory tools, byte dumps, and register documentation, while source data may sometimes arrive in octal.
Digital electronics
Conversion between 3-bit octal groups and 4-bit hex groups helps connect different compact forms of binary data.
Computer science learning
Octal-to-hex conversion is a useful demonstration of how binary can bridge two different positional number systems.
Common Octal to Hex Conversion Mistakes
Standard octal numbers contain only digits 0 through 7.
Octal digits correspond to three binary bits, not four.
Hexadecimal groups should be formed from the rightmost side of the binary integer. Pad the far-left group with zeros if needed.
Binary groups 1010 through 1111 correspond to hex digits A through F.
Related BinaryCon Tools
Reverse this conversion or continue working with octal, hexadecimal, binary, and decimal values.
Octal to Hex Converter FAQs
How do you convert octal to hexadecimal?
Convert each octal digit to three binary bits, join the groups, then split the binary value into 4-bit groups from the right. Pad the leftmost group with zeros if necessary and replace each 4-bit group with its hexadecimal digit.
What is octal 12 in hex?
Octal 12 equals decimal 10, which is hexadecimal
A. Therefore 12₈ = A₁₆.
What is octal 57 in hex?
Octal 57 maps to binary 101111. Padding and grouping gives
0010 1111, which maps to hexadecimal
2F.
What is octal 55 in hexadecimal?
Octal 55 equals decimal 45, which is hexadecimal
2D.
What is octal 377 in hexadecimal?
Octal 377 equals binary 11111111, which
groups as 1111 1111. Both groups map to F, giving
FF₁₆.
What is octal 777 in hex?
Octal 777 equals decimal 511 and hexadecimal
1FF.
Why use binary between octal and hex?
Octal maps exactly to groups of three binary bits, while hexadecimal maps exactly to groups of four binary bits. This makes binary a simple and exact bridge between the two systems.
Can I convert octal directly to hex without decimal?
Yes. The 3-bit-to-4-bit binary regrouping method does not require a decimal intermediate. Decimal conversion is another valid method, but binary grouping is usually easier by hand.
Can octal contain digits 8 or 9?
No. Standard base-8 notation uses only digits 0 through 7. BinaryCon rejects octal input containing 8 or 9.
Does hex use uppercase or lowercase letters?
Both are numerically valid. For example, 2F and
2f represent the same value. BinaryCon outputs uppercase
A through F for consistency.
Can this converter handle very large octal integers?
Yes. The calculator uses exact BigInt integer conversion rather than ordinary floating-point arithmetic, so large valid octal integers can be converted without the usual safe-integer rounding problem.
Is octal-to-hex conversion exact?
Yes for integers. Both systems represent the same integer exactly, and the binary grouping relationship introduces no rounding.
Does adding zeros before the binary groups change the value?
No. Leading zeros added only to complete the leftmost 4-bit hexadecimal group do not change an unsigned integer’s value.
Convert Octal to Hex Instantly
Use BinaryCon for exact octal-to-hex conversion, binary regrouping, uppercase hexadecimal output, verified examples, and free number-system tools without registration.