What this calculator does
This tool estimates how many calories (kcal) you burn while playing tennis. It uses the MET (metabolic equivalent of task) method, the same approach used in the international Compendium of Physical Activities and adopted by Japan's Ministry of Health, Labour and Welfare in its "Physical Activity Standards for Health 2013." Because MET values are internationally standardized, the result is not country-specific and applies anywhere.
How to use it
Enter your body weight in kilograms and how many minutes you played. Pick the type of tennis: general play (7.3 MET), singles (8.0 MET), or doubles (6.0 MET). The calculator instantly returns an estimated calorie burn. A MET is the ratio of an activity's energy cost to resting metabolism, so 1 MET is roughly the energy you use sitting still.
The formula explained
The calculation is: $$\text{kcal} = \text{MET} \times \text{weight (kg)} \times \text{hours} \times 1.05$$. The 1.05 factor converts MET-kilogram-hours into kilocalories (1 MET burns about 1.05 kcal per kilogram of body weight per hour). Since the duration field is in minutes, it is first divided by 60 to get hours.
Worked example
Suppose you weigh 60 kg and play general tennis for 90 minutes. First, \(90 / 60 = 1.5\) hours. Then $$7.3 \times 60 \times 1.5 \times 1.05 = 689.85 \text{ kcal},$$ roughly 690 kcal. If you played singles (8.0 MET) instead, you would burn $$8.0 \times 60 \times 1.5 \times 1.05 = 756 \text{ kcal}.$$
FAQ
How accurate is this estimate? It is a population average. Real energy expenditure varies with intensity, fitness level, age, and individual metabolism, so treat the number as a useful approximation.
Which MET should I pick? Use general (7.3) if you are unsure. Singles is more intense (8.0); doubles is lighter (6.0).
I only have my weight in pounds. Multiply pounds by 0.45359237 to get kilograms before entering it.
