Pool heater BTU calculator
PROBTU/hr to heat a pool to your target temperature.
Short answer: BTU/hr = (gal × 8.34 × ΔT) ÷ hours. 20,000 gal × 20°F ÷ 24 hr = 139,000 BTU/hr. Enter your measurements above and the pool heater btu calculator returns the quantity, unit conversions and an estimated cost instantly, in imperial or metric — no sign-up needed.
What do you need to measure?
What is the answer?
BTU/hr
139,000
Heater size (nearest 50k)
150k BTU
How does the pool heater btu calculator work?
BTU/hr = (gal × 8.34 × ΔT) ÷ hours.
What does a worked example look like?
20,000 gal × 20°F ÷ 24 hr = 139,000 BTU/hr.
What do people ask most?
›Gas vs heat pump?
Gas heats fast; heat pumps are 4–5× more efficient long-term.
Which pool calculator should you use next?
Where can you learn more?
Read field notes on estimating and materials, or browse every calculator we make.
What should you read before you order materials?
Field notes from real jobs that explain the numbers behind this calculator.
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