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Pool Heaters: BTU Quick Reference Charts

BTU Quick Reference Charts

Don't have a calculator handy? These quick reference charts can help you quickly choose the best heater size for your swimming pool. 

BTU Requirements for Natural Gas and Propane Pool Heaters

Pool Dimensions Surface Area Minimum BTU
14' x 28' 392 sq. ft. 130,700
15' x 30' 450 sq. ft. 150,000
16' x 32' 512 sq. ft. 170,700
18' x 36' 648 sq. ft. 216,000
20' x 40' 800 sq. ft. 266,700
24' x 44' 1,056 sq. ft. 352,000

Hourly Temperature Increase: BTU vs. Surface Area of Pool 

BTU 300 sq. ft. 400 sq. ft. 500 sq. ft. 600 sq. ft. 700 sq. ft. 800 sq. ft. 1,000 sq. ft.
100,000 1.25º 1.0º 0.75º
150,000 1.5º 1.25º 1.0º 1.0º 0.75º
250,000 2.0º 1.75º 1.5º 1.25º 1.0º 0.75º
350,000 3.0º 2.5º 2.0º 1.5º 1.25º 1.0º 0.75º
400,000 3.5º 2.75º 2.5º 2.0º 1.5º 1.25º 1.0º

Shop Residential Pool Heaters under 200k BTU

Shop Residential Pool Heaters over 200k BTU

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BTU Requirements for Electric Heat Pumps

Pool Size Heat Pump Size
15 ft Round 50,000 - 70,000 BTU
18 ft Round 50,000 - 70,000 BTU
21 ft Round 50,000 - 85,000 BTU
24 ft Round 50,000 - 110,000 BTU
27 ft Round 100,000 - 120,000 BTU
12 x 24 ft 70,000 - 85,000 BTU
16 x 32 ft 110,000 - 120,000 BTU
20 x 40 ft 120,000 - 140,000 BTU

Shop Residential Heat Pumps

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Consider the Gas Line Size

When selecting a gas pool heater, it's important to also consider your home's current natural gas or propane setup. If a gas line is already installed, you'll need to make sure it can accommodate your chosen heater. Your choice of heater will be limited by the size of the available gas line — a larger pipe size is necessary for larger heaters with a higher BTU output.

If you need to upgrade your gas line to accommodate a larger heater, your cost of installation will go up, and you may need to get a permit to complete the job. A larger gas meter and home pressure regulator will also be required. We suggest contacting your local gas utility provider to request a field review once you've identified the heater and gas line size needed. From there, they can help with determining your next steps. Each heater manufacturer carefully details the gas piping requirements needed for optimal function, and this info can often be found online through the product page or manufacturer's website.