How many watts does a Central AC (3-ton) use?

About 3500 watts while running, with a start-up surge of roughly 8500 watts. Actual draw varies by model — check the nameplate on your unit.

What size generator do I need to run a Central AC (3-ton)?

Plan on at least 4400 running watts with 8500 watts of surge capacity, which includes 25% headroom.

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What size generator to run a Central AC (3-ton)?

Typical draw: 3500W running / 8500W starting. Whole-home cooling. Realistically requires a large portable (10kW+) with a transfer switch, a soft-starter kit, or a standby generator.

SIZING PLATE1 LOADS · +25% HEADROOM

Total running watts

3,500 W

Peak (largest start)

8,500 W

Buy at least

4,400 W rated

Look for ~4,400W running / 8,500W surge or better.

Right size: Large portable (9,500W / 12,500W surge)

Typical price $1,000-1,800 · e.g. Westinghouse WGen9500DF, DuroMax XP13000EH, Champion 12.5kW tri-fuel

Most of a house through an interlock kit: well pump, multiple large appliances, even a smaller central AC with a soft-starter. Heavy (200+ lbs), thirsty, and loud — this is serious-outage equipment, not camping gear.

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One size up: Whole-home standby (18,000W / 22,000W surge)

Typical price $8,000-16,000 installed · e.g. Generac Guardian series, Kohler, Champion aXis

Everything, automatically, including central AC — turns on by itself when the grid fails. A professional installation project, not a purchase. This is where getting local installer quotes matters more than picking a model online.

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Prefer battery over fuel? See what size power station runs a Central AC (3-ton).

Add more appliances

Real outages aren't one appliance. Adjust the full load below — your Central AC (3-ton) is pre-checked.

SIZING PLATE1 LOAD · +25% HEADROOM

Total running watts

3,500 W

Peak (largest start)

8,500 W

Buy at least

4,400 W rated

Look for ~4,400W running / 8,500W surge or better.

Peak assumes your largest motor starts while everything else runs — the honest worst case. Start big motors one at a time and a smaller unit may cope, but this number won't let you down.

Kitchen Refrigerator (full-size) 300W run / 1500W start Mini fridge 90W run / 700W start Chest freezer 250W run / 1200W start Microwave (1000W) 1400W run Electric range (one burner) 1500W run Coffee maker (drip) 900W run Toaster 1100W run Electric kettle 1400W run Dishwasher 1300W run / 1500W start Instant Pot / multicooker 1000W run

Heating & cooling Window AC (5,000 BTU) 500W run / 1500W start Window AC (8,000 BTU) 800W run / 2200W start Window AC (12,000 BTU) 1100W run / 3000W start Central AC (3-ton) 3500W run / 8500W start Space heater (1500W) 1500W run Furnace blower fan (gas furnace) 600W run / 1600W start Heat pump (2-ton) 2500W run / 6000W start Box fan 100W run / 150W start Ceiling fan 75W run / 100W start

Pumps & well Sump pump (1/3 HP) 800W run / 1500W start Sump pump (1/2 HP) 1050W run / 2200W start Well pump (1/2 HP) 1000W run / 2100W start Well pump (1 HP) 2000W run / 4000W start Sewage ejector pump (1/2 HP) 1000W run / 2200W start

Electronics TV (55" LED) 80W run Wi-Fi router + modem 15W run Laptop 65W run Desktop PC + monitor 350W run / 400W start Phone charger 10W run Starlink dish + router 75W run / 100W start

Medical & safety CPAP machine 60W run Oxygen concentrator 350W run / 600W start

Lighting LED lights (per room) 30W run

Laundry Washing machine 700W run / 1600W start Clothes dryer (electric) 5000W run / 6000W start Clothes dryer (gas) 700W run / 1800W start

Household Garage door opener (1/2 HP) 550W run / 1200W start Water heater (electric tank) 4500W run EV charging (Level 1, 120V) 1400W run

Tools & outdoor Circular saw 1400W run / 2300W start Air compressor (1 HP) 1500W run / 3000W start Welder (140A MIG) 3500W run / 4000W start

RV & camping RV air conditioner (13,500 BTU) 1300W run / 2900W start RV converter/charger 500W run Electric griddle 1200W run Slow cooker 250W run

Generators that fit

Right size: Large portable (9,500W / 12,500W surge)

Typical price $1,000-1,800 · e.g. Westinghouse WGen9500DF, DuroMax XP13000EH, Champion 12.5kW tri-fuel

See current prices on Amazon

One size up: Whole-home standby (18,000W / 22,000W surge)

Typical price $8,000-16,000 installed · e.g. Generac Guardian series, Kohler, Champion aXis

See current prices on Amazon

This site earns commissions from qualifying purchases made through links to Amazon and other retailers, at no extra cost to you. Wattage figures are typical estimates — actual draw varies by model. Always verify against your appliance's nameplate, and consult a licensed electrician for any panel or hardwired connections.