How many calories do jumping jacks burn?
A jumping jack costs an average adult about 0.2 kcal. So the question everybody actually types — how many calories does 100 jumping jacks burn — has a short answer: around 20 kcal.
That is a third of a digestive biscuit. It is worth sitting with that for a moment, because the disappointment is the useful part.
The per-rep figure
Jumping jacks run at roughly 8 METs at a committed pace, around 50 reps a minute. That gives a 70 kg (155 lb) person near 10 kcal a minute, which divides down to just under 0.2 kcal a rep.
| Bodyweight | Per 100 reps | Per 10 minutes (~500 reps) | |
|---|---|---|---|
| 55 kg | 120 lb | ~15 kcal | ~75 kcal |
| 70 kg | 155 lb | ~20 kcal | ~100 kcal |
| 85 kg | 185 lb | ~24 kcal | ~120 kcal |
| 100 kg | 220 lb | ~28 kcal | ~140 kcal |
Doing them faster does not change the per-rep cost much — it just gets you to 100 sooner. A hundred reps is a hundred reps whether it takes you ninety seconds or three minutes.
Star jumps, if you mean the British name for the same arms-and-legs-out hop, are identical. If you mean the tuck-then-explode version, that is a harder movement — closer to 0.4 kcal a rep — and also not something anyone does 100 of.
What 20 kcal looks like on a plate
| kcal | Jumping jacks to match | |
|---|---|---|
| One digestive biscuit | ~70 | ~350 |
| 25 g of cheddar | ~103 | ~515 |
| One medium banana | ~105 | ~525 |
| A tablespoon of olive oil | ~120 | ~600 |
| A 330 ml can of cola | ~139 | ~695 |
| A pint of lager | ~180 | ~900 |
Nobody is doing 695 jumping jacks to offset a Coke. That is not a failure of willpower; it is the exchange rate between bodyweight movement and food. Energy goes in far faster than it comes out, which is why diet does the heavy lifting in a calorie deficit and exercise supports it.
And the daily-100 challenge, if you are wondering: 20 kcal a day for a year is about 7,300 kcal, or roughly 0.95 kg (2 lb) of fat — assuming nothing else about your day changes, which is a large assumption.
Why rep counts are a bad way to think about energy
Here is the odd thing: 100 is a perfectly accurate unit of work. It is a terrible unit of goal.
A round rep count feels like an accomplishment because it is countable and finite. But the energy cost of a bodyweight move is set by how much mass you move how far, and a jumping jack barely moves your centre of mass — a few centimetres of hop, arms swinging through air. There is no load to add. The only levers are cadence and duration, and cadence mostly compresses the same total into less time.
So a rep target optimises for the variable that matters least. Finish your 100 and you stop, at the exact point where the useful stimulus would begin.
The unit that does track energy is minutes at an intensity you can feel. Ten continuous minutes of jacks is about 100 kcal for a 70 kg (155 lb) person — five times the headline figure, from the same movement, because you stopped counting and started timing.
Gross versus net
The 20 kcal is worse than it looks, in one specific way.
A hundred jacks takes around two minutes, and across those two minutes you were going to burn about 2.5 kcal anyway just existing. So the genuinely extra figure is nearer 17 kcal. This gross-versus-net gap is the same trap that quietly inflates every step-count estimate, and it is proportionally worst for low-intensity, short-duration work — which describes a set of jumping jacks precisely.
What they are genuinely good for
A warm-up, mainly, and an excellent one. Jacks raise core temperature, move the shoulders and hips through range, and need no equipment and no skill. Two minutes before a lift or a run is time well spent.
They also work as filler inside a circuit, keeping your heart rate up through what would otherwise be rest — which raises the cost of the whole session rather than of the jacks. That is the right way to use them: a component that makes a longer piece of work harder, not the work itself.
What they will not do is reshape your week’s energy balance. Think in session totals and weekly frequency instead — how much you should be burning a day is a more useful frame than any rep count. And if you are in a deficit and want to keep the muscle you have, resistance training is the lever, not volume of hops.
One caveat: jacks are lower-impact than skipping but still a repeated landing, and a few hundred a day is real ankle and knee volume if you are carrying more weight or returning from injury. Step-jacks — one foot out at a time, no hop — remove that entirely.
General information, not medical advice.