Domino Set & Combination Counter
Pick the highest pip value (n) for a “double-n” set and see the total tile count, the doubles, and how many tiles carry any specific number.
Set breakdown
The math behind a domino set
A standard domino set is built from every unordered pair of numbers between 0 and a maximum value n, including pairs of the same number (the doubles). Counting those pairs is a classic combinations-with-repetition problem, which works out to (n+1)(n+2)/2 tiles in total. That single formula explains every common set size: 28 tiles for double-six, 55 for double-nine, 91 for double-twelve, and so on.
Doubles are simple to count separately — there’s exactly one double for each value from 0 to n, so a set always has n+1 of them. And because every number is paired with every value including itself, any single number you pick also appears on exactly n+1 tiles.
Frequently Asked Questions
Why does a double-six set have 28 tiles?
A domino tile is an unordered pair of numbers from 0 up to n, and repeats are allowed (like 3-3). That's the combinatorial formula for combinations with repetition: (n+1)(n+2)/2. For a double-six set, n = 6, so (7×8)/2 = 28.
How many doubles are in a set?
Exactly n+1 — one double for every value from 0 up to n. A double-six set has 7 doubles (0-0 through 6-6); a double-twelve set has 13.
How many tiles contain a specific number, like 5?
Every value from 0 to n is paired with every other value exactly once, including itself, so a given number appears on n+1 tiles. In a double-six set, the number 5 shows up on 7 tiles: 5-0, 5-1, 5-2, 5-3, 5-4, 5-5, and 5-6.
What set size should I use?
Double-six (28 tiles) is standard for two to four players. Double-nine (55 tiles) and double-twelve (91 tiles) are common for larger tables or games like Mexican Train that deal bigger hands.
Reference tool only. Figures reflect the standard construction of a domino set; some novelty or themed sets may differ.