How Many Calories Does Swimming Burn? By Stroke and Minute

Swimming burns about 203 to 343 kcal in 30 minutes for a 70 kg (154 lb) adult doing freestyle laps. The low end is a slow recreational pace and the high end a hard one. How many calories swimming burns for you starts with weight: the same half hour is 160 kcal at 55 kg, 261 at 90. The ratings come from the 2024 Adult Compendium of Physical Activities, which scores slow laps at 5.8 METs and fast laps at 9.8.

How Many Calories Does Swimming Burn in 30 Minutes?

Multiply the MET rating by your weight in kilograms, then by the hours you swam. That’s the whole method. The Compendium’s conversion page sets 1 MET at 1 kcal per kg per hour. So 5.8 METs at 70 kg for half an hour is 5.8 × 70 × 0.5, or 203 kcal. I ran that sum for twelve swims from the Compendium’s water list, at three body weights.

Swim (Compendium code)	METs	55 kg (121 lb)	70 kg (154 lb)	90 kg (198 lb)
Treading water, moderate effort (18350)	3.5	96 kcal	123 kcal	158 kcal
Backstroke, recreational (18255)	4.8	132 kcal	168 kcal	216 kcal
Breaststroke, recreational (18265)	5.3	146 kcal	186 kcal	239 kcal
Freestyle laps, slow, recreational (18240)	5.8	160 kcal	203 kcal	261 kcal
Leisurely swimming, not laps (18310)	6.0	165 kcal	210 kcal	270 kcal
Sidestroke (18320)	7.0	193 kcal	245 kcal	315 kcal
Crawl, medium, about 50 yd/min (18290)	8.0	220 kcal	280 kcal	360 kcal
Backstroke, training or competition (18250)	9.5	261 kcal	333 kcal	428 kcal
Freestyle laps, fast, vigorous (18230)	9.8	270 kcal	343 kcal	441 kcal
Breaststroke, training or competition (18260)	10.3	283 kcal	361 kcal	464 kcal
Crawl, fast, about 75 yd/min (18280)	10.5	289 kcal	368 kcal	473 kcal
Butterfly (18270)	13.8	380 kcal	483 kcal	621 kcal

Double any figure for an hour. These four swims show what a full hour looks like.

Swim, 60 minutes	55 kg (121 lb)	70 kg (154 lb)	90 kg (198 lb)
Freestyle laps, slow	319 kcal	406 kcal	522 kcal
Crawl, medium	440 kcal	560 kcal	720 kcal
Freestyle laps, fast	539 kcal	686 kcal	882 kcal
Butterfly	759 kcal	966 kcal	1,242 kcal

Leisurely swimming that isn’t lap swimming (6.0 METs) rates a little above slow lap freestyle (5.8). The page doesn’t say why. The gap is 0.2 METs, or 7 kcal in half an hour at 70 kg, so it hardly matters.

The same page gives a second formula for minutes: METs × 3.5 × body weight in kg ÷ 200. It comes out about 5% higher. For 5.8 METs at 70 kg over an hour that’s 426 kcal instead of 406. The tables here use the simpler 1 kcal rule.

Red type marks the estimated values on that page, and it says all the others are backed by published studies. None of the twelve rows above is red. Two other swimming rows are: lake, ocean or river swimming (18300) and synchronized swimming (18330). The authors of the 2024 update say the Compendium is a starting point and doesn’t give precise individual values. Resting energy differs with age, sex, height and body composition. Treat every cell as an estimate.

How Much of That Is Extra to What You Burn Anyway?

Less than the table shows. Remember what a MET is: the ratio of the work rate to the resting rate, as the Compendium’s own definition puts it. Every figure therefore includes the energy you’d use sitting still for the same time.

The extra is the rating minus 1, times your weight, times the hours. For slow laps at 70 kg that’s 4.8 × 70 × 0.5 = 168 kcal, out of 203 in total. Fast laps add 308 kcal out of 343 (8.8 × 70 × 0.5). The other 35 kcal is resting energy, and it sits in your daily total whatever you do.

That’s why adding the full figure to a daily calorie target can count some energy twice. If the target came from a calculator that asked about your activity, part of your swimming is already inside it. How many calories you burn a day shows how that daily total is built.

The steps to calories calculator makes the same split for walking. It takes its METs from the same 2024 Compendium and treats 1 MET as about 1 kcal per kg an hour. It shows the walk’s total next to the part that is extra to resting. It has no swimming mode, so for the pool the tables above do the job.

Which Stroke Burns the Most Calories?

Butterfly, among the common strokes. It rates 13.8 METs, which is 483 kcal in 30 minutes at 70 kg. That’s 16 kcal a minute at 70 kg, so a 4-minute butterfly set comes to about 64 kcal. Elite crawl above 90 yd/min is rated higher, at 14.5 METs, but that’s racing pace.

Effort matters as much as the stroke. Backstroke is 4.8 METs at a recreational pace and 9.5 in training or competition, nearly double. Breaststroke does the same, from 5.3 METs to 10.3.

Mixed sessions are easy to price once you split them by minutes. Take a 70 kg swimmer with 4 minutes of easy backstroke, 20 minutes of slow freestyle and 6 minutes of fast freestyle. That’s 4.8 × 70 × 4 ÷ 60 = 22 kcal, then 5.8 × 70 × 20 ÷ 60 = 135 kcal, then 9.8 × 70 × 6 ÷ 60 = 69 kcal. The half hour comes to 226 kcal.

Count the minutes you were swimming. Time spent hanging on the wall for breath belongs to the rest of your day.

Skill matters too, and no table fixes it. A 2020 review of swimming’s energy cost reports that a distance costs more to cover in water than on land. It also costs more as speed rises. The authors tie the differences between strokes, and between swimmers of different age, sex and skill, to drag and propelling efficiency. Two swimmers at the same speed can use different amounts of energy, so any row is a starting point.

How Many Calories Does a Length of the Pool, or a Mile, Burn?

About 4 to 6 kcal per length at 70 kg, going by the Compendium’s three crawl speeds. A length is one trip from wall to wall. Some people call there and back a lap and others call one length a lap, so check which your pool or watch counts.

Most public lap pools are 25 m or 25 yd long, and the difference is bigger than it looks. A yard is exactly 0.9144 m, so a 25 yd pool is 22.86 m long. Forty lengths is 1,000 yd in the short pool and 1,000 m, about 1,094 yd, in the metric one. That’s about 9% more distance.

The Compendium describes its crawl rows by speed in yards per minute, so I turned those speeds into lengths of a 25 yd pool.

Pace (Compendium code)	Yards in 30 min	Lengths of a 25-yd pool	kcal in 30 min, 70 kg	kcal per length
Crawl, slow, 30–45 yd/min (18292)	900–1,350	36–54	203 kcal	3.8–5.6 kcal
Crawl, medium, 50 yd/min (18290)	1,500	60	280 kcal	4.7 kcal
Crawl, fast, 75 yd/min (18280)	2,250	90	368 kcal	4.1 kcal

To find your row, time 100 yd. A swimmer at 75 yd/min takes 1:20 per 100 yd, at 50 yd/min 2:00, and at 45 yd/min 2:13. The slow row’s 30 yd/min is 3:20. In a metric pool, the same four speeds come to about 1:28, 2:11, 2:26 and 3:39 per 100 m.

The per-length column doesn’t climb with pace: 3.8 kcal at the fast end of the slow row, 4.7 at medium, 4.1 at fast. That looks backward, because the 2020 review says the cost of covering a distance goes up with speed. Each row is a separate entry, and nothing on the page says one swimmer produced all three. So this table prices minutes, not distances.

One small study shows how far a per-length figure can drift. In a study of 14 men aged 22, each did a 60-minute set of six blocks: about 7 minutes of swimming, then 3 of rest. The water was 28.1°C. They chose their own speed, averaged 0.74 m/s (about 49 yd/min) and covered 1,875 m. The authors didn’t measure oxygen use in the pool. They multiplied each man’s resting rate, measured on a day he didn’t swim, by a Compendium rating for the stroke he used. That gave 1,921 kJ above resting, or about 459 kcal.

That’s roughly 0.245 kcal per meter, or 6.1 kcal per 25 m length. The Compendium’s medium crawl row, with resting taken out, gives about 4.5 kcal per 25 m for a 70 kg swimmer. That’s 490 kcal an hour over 3,000 yd, or 0.163 kcal a yard. Two things in the paper close most of the gap: the men averaged 76.5 kg, about 9% more than 70. And their resting rate was 6.5 kJ a minute, about 1.2 kcal per kg per hour, where the table assumes 1.0. Stack the two and 4.5 becomes about 6. It’s one small group of young men and an estimate built on Compendium ratings, so it proves nothing about your swim. It does show how a table row can run low for one body.

A mile of swimming isn’t a mile of running. The Compendium rates running at 6 to 6.3 mph, a 10-minute mile, at 9.3 METs. The hard swimming rows, 9.8 to 10.5 METs, sit just above that. At 70 kg that’s 326 kcal in half an hour of running, against 343 to 368 kcal of swimming. Per minute, they land close.

The distances differ, though. The running half hour covers 3 miles, while crawl at 75 yd/min covers about 1.3 miles in the same time. The same NIST table puts a mile at 1,609.344 m, which is 1,760 yd. So per mile, swimming costs far more. For slower land comparisons, calories burned walking gives the walking rows, and how many calories weight lifting burns prices strength work. For the faster end of that comparison, how many calories running burns has the pace tables.

Do Swimming Watches Count Calories Correctly?

They count lengths fairly well. At easy speeds they count calories badly. In a 2018 study, 78 swimmers aged 20 to 59 wore an Apple Watch Series 2 and a Garmin Fenix 3 HR. Each swam 4 minutes at five speeds from 0.4 to 1.2 m/s while a portable gas analyzer and snorkel measured their true energy use.

Lap counts held up. Across the five speeds, Apple’s average error on laps was 0.5% to 6.1% and Garmin’s 0% to 20.6%. Calories did not. Apple’s average error ran from 17.1% to 151.7%, and its readings ran high. Garmin’s ran from 17.9% to 32.7%. Both improved as speed rose, and the authors called the estimates poor at slow to medium speeds.

Convert the speeds and the problem shows. 0.4 m/s is about 26 yd/min, slower than the Compendium’s slowest crawl row. 1.2 m/s is about 79 yd/min, near its fast row. The watches did worst where easy swimming sits.

Those were older models, and I found no later swim test that measured energy against a gas analyzer or a calorimeter. Take lengths and time from the watch, and calories from the table. How accurate Apple Watch calorie burn is covers its other workouts.

Does Swimming Make You Hungrier?

After cold water, it can. A 2023 meta-analysis of eight same-day studies found that exercise in water was followed by 330 kJ more food (about 79 kcal) than rest. The 95% interval ran from 118 to 542 kJ. Against exercise on land the difference was 78 kJ, with an interval from -176 to 334 kJ, so it can’t be told from zero.

Temperature mattered most. Two studies compared it. After exercise in cold water, 18 to 20°C, people ate 719 kJ (about 172 kcal) more than after exercise in water at 27 to 33°C. Set that beside the slow half hour in the first table, which comes to 203 kcal in total. That’s most of it. The review pools water exercise of all kinds, swimming included. The cold-water trials described in the swimming study below used cycling in the water.

The swimming study of the 14 men, in 28°C water, found no significant difference in how much they ate. Appetite dropped during the swim. It rose in the hours after. Total food at buffet meals was 9,749 kJ after swimming and 9,161 kJ on the control trial, when they didn’t swim. That gap of about 141 kcal was not statistically significant.

These are group averages from small trials. If a cold swim leaves you hungrier, log what you eat afterward like any other day.

What Should You Do With Your Swim Number Today?

Pick the row that matches how hard you swam. Multiply its rating by your weight and by the hours you actually spent swimming. Subtract 1 from the rating first if you want only the extra. Write down the row you used, so next week’s swim is priced the same way.

Then don’t chase decimals. The ratings are estimates. The one swimming study I priced came out about a third above the table. In the one watch test I found, the calorie error ran from 17% to 152%. A swim priced at 226 kcal is better read as a few hundred, which is as precise as these ratings get.

One safety line: swim where a lifeguard is on duty. If you have a heart or lung condition, ask your doctor before you push the pace.