How to use the tennis win probability calculator
Prepare the values for this calculation
Calculate the probability of winning a standard advantage tennis game from a constant independent probability of winning each point. Use the formula below to check that it answers your question. Read the input units before transferring figures from a statement, measurement or dataset.
Enter and check each input
- Probability of winning each point (%): enter a value at least 0 and no more than 100. Use the unit named in the label or selected above. Do not leave this required field blank.
The input table gives a complete example. Keep units and time periods consistent across related fields.
Calculate and resolve any input error
Choose Calculate after entering the values. Changes also update the answer after a short pause. If an error appears, follow its message, correct the field and calculate again. Reset restores the example values.
Interpret the answer
Check Game win probability first. With the unchanged example inputs, it is 62.31%. Compare the additional metrics with the primary result; each has its own label and unit.
Compare and keep a useful result
For a controlled comparison, keep every other example input unchanged and change Probability of winning each point (%) from 55 to 60.5. The resulting Game win probability is 74.61%. This illustrates the equation’s response to that input, rather than a forecast of real events.
Read the chart’s axis labels and data table. A scenario curve changes one stated input while holding the others fixed; it does not add external observations. Use Download graph to save an available chart as a PNG.
Use Copy result or Download CSV to keep the answer. Share tool shares the page address without placing your input values in the URL. Recheck inputs and assumptions before using the result for a decision.
Tennis Win Probability Calculator formula
P(game) = p⁴(1 + 4q + 10q²) + 20p³q³ × p²/(p²+q²), where q=1−p. The second term is the chance of reaching deuce times the chance of eventually winning from deuce.
Inputs and units
| Input | Format / range | Example |
|---|---|---|
| Probability of winning each point (%) | minimum 0; maximum 100 | 55 |
Worked example
Using the example inputs above, the game win probability is 62.31%.
- Game win probability
- 62.31%
- Point win probability
- 55.00%
- Chance of reaching deuce
- 30.32%
- Win probability from deuce
- 59.90%
Results and assumptions
Model assumes the same independent point-win probability throughout a standard advantage game. It does not model server changes, fatigue, score effects, tiebreaks, sets, or matches.
Fix an input or unexpected result
Probability of winning each point (%) is required. Enter probability of winning each point (%) using the format and bounds in the input table. Zero and an empty field are different: use zero only if it is allowed and represents your data.
If your answer differs from the example, choose Reset and compare every field, including selected units and options. Check percentage versus decimal entry and whether values describe the same period. Round only the final displayed answer when reproducing the formula.
If a discrepancy remains, report the calculator issue with the page address, non-sensitive example inputs, actual result, expected result and a reference for your calculation.