Swimming calorie calculator
The Compendium formula gives about 210 calories for 30 minutes of slow recreational freestyle laps at 160 pounds. That entry is code 18240 at 5.8 MET. The number changes with stroke, effort and body weight.
Estimate a swim by stroke and time
Calculated from the selected Compendium MET, body weight and swimming time.
From a swimming MET to calories
Calories = MET × body weight in kilograms × hours.
A MET puts an activity's energy cost on a common scale. The Compendium unit definitions set 1 MET equal to 1 kilocalorie per kilogram of body weight per hour. Its weight conversion is 1 kilogram = 2.2046 pounds.
For the slow freestyle example, first divide pounds by 2.2046, then turn minutes into hours. Multiply those amounts by the entry's 5.8 MET.
- 160 lb ÷ 2.2046 = 72.58 kg, rounded for display.
- 30 minutes ÷ 60 = 0.5 hours.
- 5.8 × 72.58 × 0.5 = 210.5 calories, rounded to one decimal.
The calculator keeps the unrounded kilogram value until the last step. Its whole calorie estimate is about 210.
Compare strokes over 30 minutes
| Stroke | Compendium code | MET | 130 lb | 160 lb | 190 lb | 220 lb |
|---|---|---|---|---|---|---|
| Freestyle laps, fast | 18230 | 9.8 | 289 | 356 | 422 | 489 |
| Freestyle laps, slow, recreational | 18240 | 5.8 | 171 | 210 | 250 | 289 |
| Backstroke, training or competition | 18250 | 9.5 | 280 | 345 | 409 | 474 |
| Backstroke, recreational | 18255 | 4.8 | 142 | 174 | 207 | 239 |
| Breaststroke, training or competition | 18260 | 10.3 | 304 | 374 | 444 | 514 |
| Breaststroke, recreational | 18265 | 5.3 | 156 | 192 | 228 | 264 |
| Butterfly | 18270 | 13.8 | 407 | 501 | 595 | 689 |
| Crawl, fast | 18280 | 10.5 | 310 | 381 | 452 | 524 |
| Open water, 5k | 18285 | 10.5 | 310 | 381 | 452 | 524 |
| Crawl, medium | 18290 | 8.00 | 236 | 290 | 345 | 399 |
| Crawl, slow | 18292 | 5.8 | 171 | 210 | 250 | 289 |
| Crawl, elite competition | 18294 | 14.5 | 428 | 526 | 625 | 723 |
| Lake, ocean or river | 18300 * | 6.0 | 177 | 218 | 259 | 299 |
| Leisurely swimming | 18310 | 6.0 | 177 | 218 | 259 | 299 |
| Sidestroke | 18320 | 7.0 | 206 | 254 | 302 | 349 |
| Synchronized swimming | 18330 * | 8.0 | 236 | 290 | 345 | 399 |
| Treading water, vigorous | 18340 | 9.8 | 289 | 356 | 422 | 489 |
| Treading water, moderate | 18350 | 3.5 | 103 | 127 | 151 | 175 |
* The Compendium lists the MET values for codes 18300 and 18330 as estimated.
The swimming entries behind the numbers
These descriptions and MET values are copied from the Compendium Water Activities list, checked October 6, 2026. The accompanying paper is the 2024 Adult Compendium of Physical Activities, PubMed 38242596.
| Code | Compendium description | MET |
|---|---|---|
| 18230 | Swimming laps, freestyle, fast, vigorous effort | 9.8 |
| 18240 | Swimming laps, freestyle, slow, recreational | 5.8 |
| 18250 | Swimming, backstroke, training or competition | 9.5 |
| 18255 | Swimming, backstroke, recreational | 4.8 |
| 18260 | Swimming, breaststroke, general, training or competition | 10.3 |
| 18265 | Swimming breaststroke, recreational | 5.3 |
| 18270 | Swimming, butterfly, general | 13.8 |
| 18280 | Swimming, crawl, fast speed, ~75 yards/minute, vigorous effort | 10.5 |
| 18285 | Swimming, open water, 5k | 10.5 |
| 18290 | Swimming, crawl, medium speed, ~50 yards/minute, vigorous effort | 8.00 |
| 18292 | Swimming, crawl, slow speed, 30-45 yards/minute, moderate effort | 5.8 |
| 18294 | Swimming, crawl, elite swimmers, competition, >90 yards/minute | 14.5 |
| 18300 | Swimming, lake, ocean, river (Taylor Codes 280, 295) | 6.0 |
| 18310 | Swimming, leisurely, not lap swimming, general | 6.0 |
| 18320 | Swimming, sidestroke, general | 7.0 |
| 18330 | Swimming, synchronized | 8.0 |
| 18340 | Swimming, treading water, fast, vigorous effort | 9.8 |
| 18350 | Swimming, treading water, moderate effort, general | 3.5 |
Where standard METs fall short
The Compendium was built for population studies. Finding one person's precise energy cost was outside its intended purpose.
It uses a fixed resting value of 3.5 ml/kg/min and does not adjust its MET levels for age, body mass or sex. On its corrected METs page, the Compendium cites Kozey et al., who found that standard METs misclassified the intensity category 12.2% of the time compared with measured METs. Misclassification was more frequent in people who were overweight, older, low fit, or women.
Red activity codes mean estimated MET values. The other values have published literature behind them. The Compendium also offers a corrected MET method, which this swimming calculator does not use.
Other activity and body calculations
Daily energy, including activity, is the subject of the TDEE calculator. Walking estimates have their own steps to calories calculator and 10,000 step calorie table.
For water intake, there is a water intake calculator. For body composition, the lean body mass calculator estimates the portion of body weight outside fat mass.
Food logging in TrueCal
TrueCal's free plan includes manual calorie logging, daily and weekly views, and meal history. Pro adds logging from a typed description, voice, a photo or a barcode, plus protein, carbs and fat. Nutrition results are estimates and can be wrong.
Swimming calorie questions
How many calories does swimming burn?
The Compendium formula gives about 210 calories for 30 minutes of slow recreational freestyle laps at 160 pounds. Stroke, effort and body weight change the estimate.
Which swimming stroke burns the most calories?
Butterfly has the highest MET among the general strokes at 13.8. Elite competition crawl is the highest swimming entry listed at 14.5 MET.
Does body weight change calories burned swimming?
Yes. Kilograms multiply directly into the formula, so a higher body weight gives a higher estimate for the same stroke and time.
Is treading water counted as swimming in the Compendium?
Yes. Its swimming entries include moderate treading water at 3.5 MET and fast, vigorous treading water at 9.8 MET.
References for the swimming estimates
- Compendium Water Activities codes and MET values, checked October 6, 2026.
- Compendium MET units and weight conversions, checked October 6, 2026.
- Compendium corrected METs and study limits, checked October 6, 2026.
- 2024 Adult Compendium of Physical Activities, PubMed 38242596, checked October 6, 2026.