Skip to content
SPCXTools

Number Base Converter

Convert between binary, octal, decimal, hexadecimal and any base up to 36 — instantly.

Runs locally — files never leave your device

Loading tool…

How to use Number Base Converter

  1. 1Type a number into any field — binary, octal, decimal or hexadecimal.
  2. 2All other fields update as you type. Prefixes like 0x and 0b, spaces and underscores are accepted.
  3. 3Set a custom base from 2 to 36 to convert to less common systems such as base 3 or base 36.
  4. 4Tick Group digits for readability and use the copy buttons to copy any result.

Convert between number systems instantly

Computers think in binary, programmers write colours and memory addresses in hexadecimal, Unix file permissions use octal, and people count in decimal. This number base converter translates between all of them at once: type a value in any field and see it in every other base immediately. It also converts to any custom base from 2 to 36 and handles numbers of unlimited size.

Features

  • Binary, octal, decimal and hexadecimal side by side, all editable.
  • Custom bases from 2 to 36, such as base 3, base 12 or base 36.
  • Unlimited size with exact arbitrary-precision arithmetic.
  • Negative numbers with a leading minus sign.
  • Prefixes and separators like 0x, 0b, 0o, spaces and underscores are ignored.
  • Digit grouping in fours or threes for easier reading.
  • Bit length of the number shown automatically.

Common conversions

Decimal Binary Octal Hex
10 1010 12 A
15 1111 17 F
16 10000 20 10
100 1100100 144 64
255 11111111 377 FF
1024 10000000000 2000 400
65535 1111111111111111 177777 FFFF

Where each base is used

  • Binary (base 2) — the language of digital circuits; each digit is one bit.
  • Octal (base 8) — Unix file permissions such as chmod 755, where each digit stands for three bits.
  • Decimal (base 10) — everyday numbers.
  • Hexadecimal (base 16) — memory addresses, colour codes like #FF8800, byte values, hashes and MAC addresses; each hex digit stands for exactly four bits.
  • Base 36 — compact identifiers such as short URLs, using all digits and letters.

Tips

  • One byte is 8 bits, or exactly two hexadecimal digits — FF is 255, the largest byte value.
  • To convert hex colour codes to RGB values, use the Color Converter.
  • For calculations with powers of two, the Scientific Calculator supports expressions like 2^32.

Frequently asked questions

How do I convert binary to decimal?
Multiply each binary digit by its place value — 1, 2, 4, 8, 16 and so on from right to left — and add the results. For 1011: 1×8 + 0×4 + 1×2 + 1×1 = 11. The converter does this instantly for numbers of any length.
How do I convert decimal to hexadecimal?
Divide the number by 16 repeatedly and write down the remainders, using A–F for 10–15, then read them from bottom to top. For 255: 255 ÷ 16 = 15 remainder 15 (F), and 15 ÷ 16 = 0 remainder 15 (F), so 255 = FF.
Is there a limit on the size of the number?
No. The converter uses arbitrary-precision integers (BigInt), so even numbers with hundreds of digits convert exactly, without the rounding errors that ordinary calculators have above about 9 quadrillion.
Can I convert negative numbers or fractions?
Negative numbers are supported with a leading minus sign, such as −FF = −255. Fractions are not supported; the converter works with whole numbers only. Two's complement representation is not applied — the minus sign is kept as is.
Which digits are used for bases above 10?
Letters A–Z represent the values 10 to 35, so hexadecimal uses 0–9 and A–F, and base 36 uses all digits and all letters. Input is case-insensitive.

Related tools

Scientific CalculatorTrigonometry, logarithms, powers, roots and more — type an expression or tap the keys.Base64 Encode & DecodeConvert text and files to Base64 and back, with full UTF-8 and Base64URL support.Hash GeneratorCalculate MD5 and SHA checksums for text or files and verify downloads against a known hash.Currency ConverterConvert money between 30+ major currencies using daily reference exchange rates.Time Zone ConverterConvert any time between time zones and compare cities side by side — daylight saving included.Unit ConverterConvert between metric and imperial units across ten kinds of measurement, with all results at a glance.