MyFitnessPal says I burn about 570 calories in one hour singles. I weigh 160 lbs. I think it's about correct, because I do drills for 1 hour. Playing sets feels less exhausting, so I would maybe change the number down depending how much exertion I feel. I eat about 3,300 calories per day to keep my weight at 160 lbs, playing 90 mins tennis, walk the dog for one hour, and a little workout or bike ride here and there.
I think it depends also on how much muscles (or fat) you have, how high/low metabolism you have and many more factors. Just log in what MFP says, your calories in and out and see if you are losing/gaining weight (whatever your goal is). Then you will see if you need to adjust something.
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