Base Conversion Tool
Bases Greater than 10
What happens when you need more than 10 digits?
Undecimal (Base 11)
Undecimal (Base 11) needs one more digit than Decimal, so "A" is used, like this:
| Decimal: | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | ... |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Undecimal: | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | 10 | 11 | ... |
Duodecimal (Base 12)
Duodecimal (Base 12) needs two more digits than Decimal, so "A" and "B" are used:
| Decimal: | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | ... |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Duodecimal: | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | 10 | 11 | ... |
Hexadecimal (Base 16)
Because there are more than 10 digits, hexadecimal is written using letters as well, like this:
| Decimal: | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | ... |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Hexadecimal: | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F | 10 | 11 | ... |
Vigesimal (Base 20)
With vigesimal, the convention is that I is not used because it looks like 1, so J=18 and K=19, as in this table:
| Decimal: | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | ... |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Vigesimal: | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F | G | H | J | K | 10 | ... |
Letters (Base 26)
With "Base 26", you use the letters of the alphabet (not 0 to 9).
Some people start with A=0, B=1, etc. But it seems more natural to use A=1, B=2, etc, as everyone thinks that A is the first letter, B is the second, and so on.
So I use the A=1, B=2, convention, and I use "Z" for Zero! Like this:
| Decimal: | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | ... |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Base 26: | Z | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | AZ | AA | ... |
It is fun to use Base 26, type your name in, and see what number you are!
Also, try putting in decimal values after the ".", for example 0.1 produces "BOOO..."