Nothing beats a pleasant swim in perfectly heated water—even when the evenings are cool. To make that happen, a good pool heater makes all the difference. Whether you have an above-ground or in-ground pool, the heater size must be properly matched to your pool volume to ensure optimal performance without energy waste.
Use our guide below to select the ideal pool heater based on your pool’s dimensions.
Heater Sizing Guide Based on Your Pool Type
Heaters for Above-Ground Pools
| Pool Type | Pool Size (Liters) | Heater Size | Models |
| Above-ground | 15' Round (21,600 liters) | 200,000 BTU | Shop 200,000 BTU heaters |
| Above-ground | 18' Round (31,200 liters) | 200,000 BTU | Shop 200,000 BTU heaters |
| Above-ground | 21' Round (42,400 liters) | 200,000 BTU | Shop 200,000 BTU heaters |
| Above-ground | 24' Round (55,200 liters) | 250,000 BTU | Shop 200,000 to 300,000 BTU heaters |
| Above-ground | 27' Round (70,000 liters) | 300,000 BTU | Shop 300,000 BTU heaters |
| Above-ground | 30' Round (86,400 liters) | 350,000 BTU | Shop 330,000 to 400,000 BTU heaters |
Heaters for In-Ground Pools
| Pool Type | Pool Size (Liters) | Heater Size | Models |
| In-ground | 12' x 24' (32,628 liters) | 200,000 BTU | Shop 200,000 BTU heaters |
| In-ground | 14' x 28' (44,391 liters) | 200,000 BTU | Shop 200,000 BTU heaters |
| In-ground | 16' x 32' (58,003 liters) | 250,000 BTU | Shop 200,000 to 300,000 BTU heaters |
| In-ground | 18' x 36' (73,487 liters) | 300,000 BTU | Shop 300,000 BTU heaters |
| In-ground | 20' x 40' (90,847 liters) | Between 350,000 and 400,000 BTU | Shop 350,000 to 400,000 BTU heaters |
* Figures provided are for reference only.
* Above-ground pool volumes based on a depth of 52''. In-ground pools based on a depth of 48''.