Number Base Converter – Binary, Hex, Decimal

Convert between binary, octal, decimal, hexadecimal and any base from 2 to 36 — exact for very large numbers.

Last updated:

Number base converter

Programmers, electronics students and anyone studying computer science regularly switch betweenbinary, octal, decimal and hexadecimal. This converter shows a number in all four at once — plus any base you choose — and handles very large integers exactly. Paste values like 0xFF or0b1010 directly.

How to use it

  1. Type the number and choose the base it's written in.
  2. Read it in binary, octal, decimal and hexadecimal; tap a value to copy it.

Example

The decimal number 255 is 11111111 in binary (eight 1s — one byte), 377 in octal and FF in hexadecimal, which is why the brightest red in web colours is #FF0000. Unix permission 755 (octal) is 111 101 101 in binary: read-write-execute for the owner and read-execute for others. Need Roman numerals instead? Try the Roman numerals converter.

Frequently asked questions

How do I convert decimal to binary?
Divide the number by 2 repeatedly and write down the remainders from bottom to top. 13 ÷ 2 = 6 r1, 6 ÷ 2 = 3 r0, 3 ÷ 2 = 1 r1, 1 ÷ 2 = 0 r1, so 13 = 1101 in binary.
What are hexadecimal and octal?
Hexadecimal is base 16, using digits 0–9 and letters A–F (A = 10 … F = 15). It is used for colours (#FF8800) and memory addresses. Octal is base 8, used in Unix file permissions (755).
Can I convert very large numbers?
Yes. The converter uses big-integer arithmetic, so numbers with dozens of digits convert exactly without rounding.
Can I use other bases?
Yes — any base from 2 to 36 is supported, using 0–9 and then A–Z as digits.

Roman Numerals Converter

Convert numbers to Roman numerals and Roman numerals back to numbers, from 1 to 3,999, with a breakdown of each part and the rules explained.

Scientific Calculator

Free online scientific calculator with sin, cos, tan, logs, powers, roots and factorials — degree and radian modes and a history of results.

Exponent Calculator

Calculate powers and exponents, including negative and fractional powers, with the working shown and results in scientific notation.

Prime Number Checker

Check if a number is prime and find its prime factorization, number of divisors and the nearest primes — fast even for 20-digit numbers.

Percentage Calculator

Calculate percentages instantly: X% of Y, percentage change, increase/decrease and what percent one number is of another.

CGPA to Percentage

Convert CGPA to percentage with the official formula for CBSE, VTU, Anna University, JNTU, GTU and AKTU — and back.