Digit reference (10 = A, 35 = Z)
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F |
Hex digits 0–F. Bases above 16 continue with G (16) up to Z (35).
Related Tools
About the Number Base Converter
Positional numeral systems represent numbers using a fixed set of digits whose position carries weight. Base 10 (decimal) uses digits 0–9 because humans count on ten fingers; base 2 (binary) uses 0 and 1 because transistors have two stable states; base 8 (octal) and base 16 (hexadecimal) exist because they map neatly onto binary — one octal digit is three bits, one hex digit is four.
This converter works in all four standard bases plus any custom base from 2 to 36, where digits beyond 9 continue with letters A–Z (A = 10 through Z = 35). Type a value into any field and every other field updates instantly. Conversions use arbitrary-precision BigInt arithmetic, so numbers far beyond JavaScript’s normal 2⁵³ limit convert exactly — useful for hashes, flags, and big identifiers.
The tool also validates as you type: a value like 129 in binary is flagged with a clear error rather than silently misread, which is where most manual conversions go wrong.
How to use the Number Base Converter
- 1 Type or paste a number into any base field — binary, octal, decimal, hex, or the custom-base field.
- 2 Every other field updates instantly with the converted value.
- 3 For a non-standard base, set the custom base (2–36) and type the value using digits and letters (case-insensitive).
- 4 Use Clear all to reset, or Copy decimal to grab the plain decimal value for other tools.
Key features
All standard bases
Binary, octal, decimal, and hexadecimal convert simultaneously as you type.
Custom bases 2–36
Alphanumeric digits A–Z extend conversion beyond the standard four systems.
BigInt precision
Arbitrary-size integers convert exactly — no floating-point silent rounding.
Live validation
Invalid digits for a base are caught instantly with a descriptive error.
Who uses the Number Base Converter?
- Programmers reading debug output, memory addresses, and colour codes.
- Networking students converting subnet masks and IP octets.
- Embedded developers working with register values and bit flags.
- Students learning positional number systems with instant feedback.
- Puzzle and CTF enthusiasts decoding numeric ciphers and encodings.
Tips and best practices
- Memorise the bit anchors: 255 is FF in hex (eight ones), 1024 is 2¹⁰, and each hex digit is exactly four binary digits.
- Prefixes matter in code: 0x means hex (0xFF), 0b binary (0b1011), 0o octal (0o377) in modern languages.
- Hexadecimal is the readable shorthand for binary — comparing two hex values digit-by-digit is comparing four bits at a time.
- For negative numbers in hardware contexts, check two’s-complement representation rather than assuming a minus sign.
- Base 36 is the practical maximum for alphanumeric encoding — useful for compact, URL-safe numeric identifiers.
Frequently asked questions
Positional systems with different bases: binary is base 2 (digits 0–1), octal base 8 (0–7), decimal base 10 (0–9), hexadecimal base 16 (0–9 then A–F). Computers work in binary; hex is a compact shorthand where one digit equals four bits.
Bases above 10 use letters as extra digits: A = 10 up to Z = 35. Base 36 uses all ten digits and all 26 letters — the practical maximum for alphanumeric notation.
Divide by 2 repeatedly, noting each remainder; reading remainders last-to-first gives the binary. Example: 13 → remainders 1,0,1,1 → 1101.
Each hex digit maps exactly to four binary bits, so long binary strings become short and readable — colours like #FF8000, memory addresses, and byte values are far easier to scan in hex.
Yes — conversion uses BigInt arithmetic, so values far beyond 2⁵³ (JavaScript’s normal integer limit) convert exactly, including long hashes and identifiers.