Free tennis betting maths tool
Enter decimal odds to convert a bookmaker price into its implied probability, break-even strike rate and hypothetical return. You can also compare those odds with your own estimated chance of winning. This calculator does not predict a match or retrieve live odds.
Compare your own probability estimate
Optional: enter your own estimated chance of winning to see the hypothetical fair odds and expected value. Tennis Tips UK is not supplying a predicted win probability here.
A positive EV calculated from your estimate is not proof of a real advantage. If your estimate is wrong, the actual expectation changes. All bets can lose.
What do decimal odds mean?
Odds of 2.00 imply a 50% break-even win rate. Odds of 2.50 imply a 40% break-even win rate. At odds of 2.10, the implied probability is approximately 47.62%. These figures come from the quoted price, not an independent prediction of who will win.
How do you work out implied probability?
Implied probability (%) = 100 ÷ decimal odds. The same percentage is the long-run break-even strike rate if all your bets were taken at that price, ignoring fees and commission.
What is value betting?
You might estimate a player’s winning chance independently and compare that estimate with the market’s implied probability. The optional box above calculates your own assumptions. If those assumptions are inaccurate, a calculated positive expected value can disappear. Tennis matches remain uncertain and any individual bet can lose.
What about bookmaker margin?
A quoted price already reflects the bookmaker’s market. In a two-player match, adding the implied probabilities of both players’ available prices will often exceed 100% because of the bookmaker’s margin (overround). A single quote cannot reveal the entire margin, and implied probability is not necessarily the player’s true probability.
Useful next steps
See what the recorded club results would have returned at your stakes →
Inspect the full historical betting record →
Read about staking and units →
Historical performance does not guarantee future returns. This is an educational calculator, not a bookmaker recommendation or betting instruction.