Bigger isn't always better for pool heaters.

Usually a 50,000 to 75,000 BTU unit is plenty for most above-ground pools.

Above-ground pools are smaller than in-ground ones — typically 5,000 to 15,000 gallons. You don’t need a monster heater. A 100,000 BTU unit might sound impressive, but it’ll short-cycle (turn on and off too often), waste gas, and wear out faster. Too small and you’ll be waiting all day for the water to warm up.

A rough rule: for every 10,000 gallons, you want about 50,000 BTUs to raise the temp 10°F in a couple hours on an average day. So for a common 12,000–15,000 gallon pool, a 75,000 BTU heater is the sweet spot. Colder climates or if you want hotter water faster? Push toward 100,000, but no higher.

Don’t overthink it. Just match the heater to your pool volume, not your ego.