General
Number Base Converter
Convert between binary, decimal, octal, hexadecimal, and any base (2–36). Quick converter shows all 4 bases simultaneously with step-by-step working.
Enter a number and click Convert
How is this calculated?
To decimal: Σ(digit × base^position) right-to-left
From decimal: repeatedly divide by target base, collect remainders
255 in binary: 255÷2=127R1, 127÷2=63R1, ... → 11111111
Hex digits: 0-9, A=10, B=11, C=12, D=13, E=14, F=15
Quick: 1 hex digit = 4 binary bits, 1 octal = 3 bitsFAQ
Frequently asked questions about number bases
How do I convert decimal to binary?
Repeatedly divide by 2 and record remainders from bottom to top. For example, 13: 13÷2=6 R1, 6÷2=3 R0, 3÷2=1 R1, 1÷2=0 R1. Read remainders bottom-up: 1101.
How do I convert binary to decimal?
Multiply each bit by 2 raised to its position (right-to-left starting at 0), then sum. For 1101: 1×8 + 1×4 + 0×2 + 1×1 = 13.
What is hexadecimal?
Base-16 number system using digits 0-9 and letters A-F (A=10, B=11, C=12, D=13, E=14, F=15). Common in programming for colors (#FF0000), memory addresses, and byte values.
What is octal?
Base-8 number system using digits 0-7. Used in Unix file permissions (chmod 755) and some legacy systems. Each octal digit represents exactly 3 binary bits.
Can I convert between any base?
Yes! The Custom Base tab lets you convert between any bases from 2 to 36. Bases above 10 use letters A-Z as additional digits.
Is this number base converter free?
Yes, completely free with no sign-up required. All conversions run in your browser — your data stays on your device and is never sent to any server.