Hammer CalculatorCalculators / Pools / Pool Heater Sizing
Pool Heater Sizing Calculator
Determine the right heater size for your pool and compare gas, heat pump, and solar options by BTU output, monthly cost, and equipment price.
Pool Heater Sizing Calculator
Environment
Energy Pricing (edit to match local rates)
Gas Heater Size
250,000 BTU
for 20,000 gal, +20°F
Monthly Operating Cost
$375.30
~180 hrs/mo run time
Time to Heat
~24 hours
173,750 BTU/hr needed
Cost Comparison — All Heater Types
| Purchase Option | Quantity | Est. Cost |
|---|---|---|
| Gas Heater | 250,000 BTU | $375.30/mo |
| Heat Pump | 140,000 BTU (9 kW input) | $216.66/mo |
| Solar PanelsBest value | 240 sq ft of panels | $0.00/mo |
Equipment Cost Ranges (installed)
Gas Heater
$1,500 – $3,500
+ $375.30/mo operating
Heat Pump
$3,000 – $6,000
+ $216.66/mo operating
Solar Panels
$2,500 – $5,000
+ $0.00/mo operating
Recommended: Gas Heater — 250,000 BTUA 250,000 BTU gas heater will raise your 20,000-gallon pool by 20°F in approximately 24 hours. Gas heaters heat quickly and work well in any climate, but have higher operating costs.
Solar covers reduce heat loss by 50–70%Adding a solar cover (also called a solar blanket) is one of the most cost-effective ways to reduce heating costs. It minimizes evaporation — the primary source of heat loss — and can cut your monthly heating bill significantly. Toggle "Solar Cover" above to see the impact on sizing and cost.
Consider a heat pump for lower operating costsWhile gas heats faster, a heat pump would cost $158.64 less per month to operate. The higher upfront cost typically pays for itself within 2–3 years.
This is an estimate based on simplified heat-loss models. Actual heater performance depends on climate, insulation, wind, shade, and usage patterns. Consult a pool professional for precise sizing. Operating costs assume average monthly run times and may vary seasonally.