About the Double Fault Percentage Calculator
Double fault percentage of service points — a key serve-reliability stat.
Also known as: double faults rate, df percentage.
How to use this calculator
- Enter double faults, service points.
- The result updates instantly as you type — press Calculate (or Enter) at any time.
- Open “Step-by-step” to see how the answer was worked out.
- Use Copy result or Share to save the answer or send a link with your inputs.
Formula
Double fault percentage = Double faults ÷ Service points × 100
Worked example
Using the values pre-filled in the calculator above:
- Double faults = 4
- Service points = 68
the calculator returns:
- Double fault percentage: 5.88%
Working
Double fault percentage = 4 ÷ 68 × 100 = 5.8824%