Any sport · Calculator
A perfect season needs every game won, and the chances multiply. A team that wins nine games in ten goes 20–0 roughly once in every eight tries, and 162–0 about once in 26 million: the same team, a very different result, purely because of length.
Enter one game’s chance of a win — and of a draw, in sports that have them — and the calculator shows the chance of a perfect season, an unbeaten one, and a season with at most one or two losses. It treats every game as having the same chances and the games as independent of each other, which no real season is; the limits below explain what that leaves out.
By Reign Creative LLCPublished More in the sports hubs
Enter one game’s chances as percentages. The same chances apply to every game.
Perfect season (20–0)12.2%1 in 8.2
Perfect season, n games
P(n–0) = wn
Unbeaten season (no losses)
P(unbeaten) = (w + d)n
Exactly k losses
P(k) = C(n, k) · lk · (1 − l)n − k
Here w, d and l are one game’s chances of a win, a draw and a loss, adding up to 1, and C(n, k) is the number of ways to choose which k of the n games are lost. The last line is the binomial distribution as NIST’s e-Handbook of Statistical Methods writes it, with a loss as one outcome and anything else as the other; “at most one loss” adds the cases for 0 and 1.
NIST notes that the binomial distribution assumes the chance is fixed for all trials. Here that means the same chances in every game, and a result in one game that tells you nothing about the next.
Illustrative chances, not real teams. The table shows the chance of winning every game for three season lengths and three per-game win chances, with no draws:
| Win chance a game | 20–0 | 82–0 | 162–0 |
|---|---|---|---|
| 80% | 1.2% · 1 in 86.7 | <0.1% · 1 in 88.4 million | <0.1% · 1 in 5.01 × 10¹⁵ |
| 90% | 12.2% · 1 in 8.2 | <0.1% · 1 in 5,650 | <0.1% · 1 in 25.9 million |
| 95% | 35.8% · 1 in 2.8 | 1.5% · 1 in 67.1 | <0.1% · 1 in 4,060 |
At 90% a game, 20–0 happens about once in 8.2 seasons, while 162–0 is 1 in 25.9 million. Moving from 90% to 95% a game turns 162–0 into 1 in 4,060: small per-game edges compound over a long season, and so do small weaknesses. For an even chance of going 162–0 a team would need to win about 99.6% of its games; for 20–0, about 96.6%.
With draws, perfect and unbeaten come apart. In a 38-game season where a side wins 70% of games and draws 20%, winning every game is 1 in 770,000, but losing none is 1.8% · 1 in 54.8: the draws carry most of the unbeaten chance.
Any other length — a 40-fight career, a cup run, a short season — works as a custom number of games.
For why even a dominant simulated team loses, and how simulators turn ratings into results, read understanding probability in sports simulations.
40-0 MMA & Boxing Fight Draft is built around the same target: forty fights without a loss. Its simulators settle each bout on style, ratings and weight class, so the higher-rated fighter does not always get the nod — which is why getting a stable to 40–0 is the whole challenge.
Reign Creative LLC makes 40-0 MMA & Boxing Fight Draft, so we have a commercial interest in it. It is not affiliated with, or endorsed by, any league, team, players’ association or athlete.
Good to know
League, governing-body and team names appear here only to identify the formulas and rules being used. Reign Creative LLC's sports games and calculators are not affiliated with, endorsed by or licensed by any league, team, players' association or athlete, and all names and marks belong to their owners.
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