Number Base Converter

Convert integers between the four most common number bases used in software development — and explore a hidden layer of historical and extended systems used by ancient civilisations that still shape the modern world.

Everyday Bases

• Decimal (Base 10) — Standard integer notation.
• Hexadecimal (Base 16) — The go-to format for memory addresses, colours, and byte values.
• Binary (Base 2) — Bit-level representation. Essential for bitmasking and low-level work.
• Octal (Base 8) — Common in Unix file permissions and legacy systems.

Historical & Extended Bases

Expand the Historical & Extended Bases section to reveal five additional systems:

• Base 36 (Alphanumeric) — Uses digits 0–9 and letters A–Z. Seen in URL shorteners, Git short-hashes, and compact numeric IDs.
• Duodecimal (Base 12) — Preferred by many ancient cultures for its divisibility. Still alive in dozens, inches per foot, and clock faces. Digits A = 10, B = 11.
• Vigesimal (Base 20) — Used by the Maya and Aztec civilisations. Their entire calendar and mathematics were built on multiples of twenty. Digits A = 10 through J = 19.
• Sexagesimal (Base 60) — Invented by the Sumerians around 3000 BCE and adopted by Babylon. Its legacy is everywhere: 60 seconds in a minute, 60 minutes in an hour, 360 degrees in a circle. Expressed as colon-separated groups of 0–59 (e.g. 90 = 1:30).
• Roman Numerals — The additive notation of the Roman Empire. Uses subtractive pairs (IV = 4, IX = 9, XL = 40, XC = 90, CD = 400, CM = 900) for compactness. Supports values from I (1) to MMMCMXCIX (3999).

Key Features

• Fully bidirectional — Type in any field (standard or historical) and all others update instantly.
• Bit viewer — See the number laid out in 8, 16, 32, or 64-bit binary.
• Large integer support — Uses JavaScript BigInt for safe handling of large values.
• Quick values — Shortcuts for 0, 1, 255, 256, 1024, 65535, and 2³¹−1.

[!TIP] Type 1:0 in the Sexagesimal field to see the number 60 ripple across all other bases. It’s a satisfying way to build intuition for base-60 arithmetic.