Number Base Converter
Convert exactly between decimal, binary, octal and hexadecimal — enter a value in any base and see it in all four instantly.
What is a number base converter?
A number base — also called a radix — is the set of digits used to write numbers. Decimal is base-10 with digits 0-9, binary is base-2 with just 0 and 1, octal is base-8 with 0-7, and hexadecimal is base-16 with 0-9 plus A-F. A base converter takes a value written in one base and re-expresses it in another, which is essential because both humans and machines work with different ones. Computers are built from binary, but long binary strings are hard to read, so developers use hexadecimal as a compact shorthand — one hex digit maps to exactly four bits — and octal appears in Unix permissions. This converter accepts a number in any base from 2 to 36, parses it with a big-integer approach so large values stay exact, and instantly shows the decimal, binary, octal and hexadecimal equivalents. It is a handy checking tool for coding, debugging, digital electronics and coursework, and it runs entirely in your browser.
Example
Select base 10, enter 255, and the tool shows decimal 255, binary 11111111, octal 377 and hexadecimal FF. Switch the base to 2 and type 101010 to see it resolve to decimal 42, octal 52 and hex 2A.
Who is this number base converter for?
This free number base converter is built for anyone who needs to make a conversion quickly, but a few groups reach for it most often.
- Students and young adults: Computer science starts with binary, octal and hex. A number base converter for students shows the same value written across bases.
- Designers and developers: Reading hex colour or memory addresses is easier with a number base converter beside you.
- Professionals: Systems engineers and network admins use the number base converter to check an IP address or a bitmask.
- Curious users: If you have ever wanted to learn how numbers change between bases, the number base converter shows it instantly.
Number base reference table
Every row is the same integer written in the four bases the converter handles; hex is uppercase to match the tool output.
| Decimal | Binary | Octal | Hex |
|---|---|---|---|
| 0 | 0 | 0 | 0 |
| 1 | 1 | 1 | 1 |
| 26 | 11010 | 32 | 1A |
| 42 | 101010 | 52 | 2A |
| 100 | 1100100 | 144 | 64 |
| 255 | 11111111 | 377 | FF |
| 1000 | 1111101000 | 1750 | 3E8 |
| 2550 | 100111110110 | 4766 | 9F6 |
Common use cases
- Reading hex memory addresses, debugger values or MAC address bytes.
- Decoding Unix file permissions —
755in octal becomes the binary bit pattern for rwx. - Working with CSS hex colors or byte-level data such as subnet masks.
- Checking conversions by hand while studying computer architecture or digital logic.
Pro tips
- One hex digit equals four bits (a nibble), so split a long binary number into groups of four to read it in hex almost instantly.
- The 0x prefix signals hexadecimal, 0b signals binary and 0o signals octal in many languages.
- Octal maps cleanly to three-bit groups, which is why it still lives on in file permissions.
- Large integers are handled exactly with a big-integer parser, so values beyond 32-bit are not truncated.
How to use
- Choose the base your number is written in — decimal, binary, octal or hexadecimal.
- Type the value in that base.
- The number is converted to all four bases instantly.
- Hexadecimal digits can be typed in upper or lower case.
FAQ
How do I convert decimal to binary?
Pick Decimal as the input base, type a number, and the binary, octal and hexadecimal values appear instantly. 255 in decimal is 11111111 in binary and FF in hex.
What is hexadecimal used for?
Hexadecimal (base 16) is widely used in computing to represent bytes and memory addresses compactly, where FF equals 255 in decimal.
How large can the numbers be?
The converter handles integers exactly for values up to and beyond 53 bits, so it is safe for any normal 32-bit or 64-bit number.
Is this converter free and private?
Yes. It is free, runs in your browser, and no data is uploaded.
What is binary?
Binary is base-2, using only 0 and 1. Every digital system stores and processes data as binary.
What is hexadecimal used for?
Hex is a compact way to write bytes — two hex digits equal one byte — so it is used for colors, addresses and debugging output.
How do I convert decimal to binary?
Repeatedly divide by 2 and record the remainders, then read them bottom to top. For example, 10 becomes 1010.
What does the 0x prefix mean?
It marks a number as hexadecimal in code, so 0xFF means 255 in decimal.
Where is octal still used?
Mostly for Unix and Linux file permissions, like chmod 755, where each digit maps to three permission bits.
Can it convert negative numbers?
Yes, a leading minus sign is parsed and applied, so negative values convert correctly across bases.
More FAQs
Are these tools free to use?
Yes, every tool is completely free, with no signup and no limits.
Do I need an account or install anything?
No. Everything runs in your browser — no install, no account.
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