How many watts does a Central AC (3-ton / 36,000 BTU) use?

A Central AC (3-ton / 36,000 BTU) draws 3,500 watts continuously once it's running, but its motor needs a brief surge of up to 25,750 watts to start. A generator has to cover that starting surge, not just the running load, or the motor won't start. High starting surge from the compressor — often the single largest load in a house. Based on Copeland's published R410A 3-ton scroll compressor spec (105-124A LRA at 230V, centered ~112A) — real compressor nameplate data, not a rough multiplier. This is dramatically higher than a simple running-watts multiplier would suggest, which is exactly why central air is close to mandatory soft-starter territory.

Running it 8 hours/day costs roughly $142.80/month at the U.S. average residential rate (~$0.17/kWh, early 2026, per the EIA) — real rates vary a lot by state and utility. Use your own rate in the House calculator →

Generators that can run this

Prices as of July 2026 — check the current listing before buying.