Tennis Serve Speed Converter
Convert tennis serve speeds instantly between mph and km/h. Use this when scouting players, analyzing match data, or comparing serve speeds across international broadcasts that use different units.
Last updated: September 2026
Formula below · 1 source (Wikipedia) · Updated Sep 2026
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About this calculator
Tennis serve speeds are measured in miles per hour (mph) in the United States and kilometers per hour (km/h) in most other countries. Converting between the two requires multiplying by the fixed ratio between the units. The formula is: speed_kmh = speed_mph × 1.60934. This constant (1.60934) represents the exact number of kilometers in one mile. For the reverse conversion, divide by 1.60934 (or multiply by 0.62137). World-class servers like John Isner regularly clock serves above 230 km/h (143 mph), so accurate conversion matters when comparing player statistics across different data sources or broadcasts.
How to use
Suppose a player's first serve is clocked at 130 mph on a US broadcast, and you want the km/h equivalent for a European stats sheet. Apply the formula: speed_kmh = 130 × 1.60934 = 209.2 km/h. Conversely, if a serve is listed as 200 km/h, divide: 200 ÷ 1.60934 = 124.3 mph. Enter your mph value in the Serve Speed field and the calculator returns the km/h result instantly, removing any manual conversion errors.
Frequently asked questions
How do I convert tennis serve speed from mph to km/h accurately?
Multiply the mph value by 1.60934 to get km/h. This constant is the precise number of kilometers in one statute mile. For example, 140 mph × 1.60934 = 225.3 km/h. Using the exact constant rather than rounding to 1.6 prevents small but cumulative errors when comparing multiple serves.
What is the average professional tennis serve speed in mph and km/h?
The average first-serve speed on the ATP Tour sits around 180–200 km/h (112–124 mph) for men, while WTA players typically average 150–170 km/h (93–106 mph). Second serves are considerably slower, often 130–160 km/h (81–99 mph), to prioritize spin and placement over raw pace. Top servers like Reilly Opelka and Sam Groth have recorded official first-serve speeds exceeding 250 km/h (155 mph).
Why do some tennis broadcasts show serve speed in mph while others use km/h?
The unit used depends primarily on the country of broadcast. US tournaments and networks default to mph, while European and Australian broadcasts typically use km/h, reflecting local measurement conventions. The underlying radar gun data is the same; it is simply displayed in the locally preferred unit. This is why a conversion tool is essential when comparing player statistics from different Grand Slam sources.