Swimming Pool Heater BTU Calculator

To help estimate the BTU size, enter all of your information regarding your pool using the drop down menus and click on the calculate button.

Please note that heat rise varies when dealing with different heaters. The usual recommendation is an increase of 1 to 1 and a half degree per hour.


  • Most newer heaters are at least 83% efficient.
  • Heaters manufactured prior to 1996 are 78% efficient.
  • Calculations are rough estimates as to which size pool heater you may need.
  • Consult with a certified pool installer to verify the minimum heater size required OR call our customer service team.

We recommend you size your heater one size larger than required. Shop swimming pool heaters from our online store.

Surface area of pool (Sq. ft):
Efficiency of heater (%):
Desired temperature rise (F):
Wind (mph):
Criteria  Results Below
Required Natural Gas Heater Output (BTU/Hr.):
Minimum Natural Gas Heater Size Required:
Required Propane Heater Output (BTU/Hr.):
Minimum Propane Heater Size Required: