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What size generator do you actually need?
Check the appliances that must run at the same time. We add the running watts, apply the single-largest starting surge (staggered starts), add 25% headroom, and recommend a size class — not a brand.
Build your load — check what must run at the same time
Totals update live. Surge math assumes staggered starts: plug loads in one at a time, largest motor last. 25% headroom applied.
- Storm backup essentials“generator size for storm backup essentials”
- Home essentials + well pump“generator size for well pump and refrigerator”
- Home essentials + sump pump“generator size for sump pump and refrigerator”
- Essentials + furnace in winter“generator size for furnace and essentials in winter”
- Whole house with central AC“what size generator for whole house with central ac”
- RV weekend setup“what size generator for rv weekend camping”
- Refrigerator Generator Size Calculator“what size generator to run a refrigerator”
- Chest Freezer Generator Size Calculator“what size generator to run a chest freezer”
- TV, Wi-Fi & Lights Generator Calculator“generator size for tv wifi and lights”
- Home Office Generator Size Calculator“what size generator to power a home office”
- CPAP & Medical Device Generator Calculator“generator size for cpap machine”
- Dehumidifier Generator Size Calculator“how many watts to run a dehumidifier on a generator”
- Garage Door Opener Generator Calculator“will a generator run a garage door opener”
- Washing Machine Generator Size Calculator“what size generator to run a washing machine”
- EV Charging From a Generator: Honest Calculator“can a generator charge an electric car”
- Central AC Generator Size Calculator (by Tonnage)“what size generator to run central air conditioner”
- Window AC Generator Size Calculator (by BTU)“what size generator to run a window air conditioner”
- Furnace Blower Generator Size Calculator“what size generator to run a furnace”
- Electric Space Heater Generator Calculator“can a generator run a space heater”
- Well Pump Generator Size Calculator (by HP)“what size generator to run a well pump”
- Sump Pump Generator Size Calculator (by HP)“what size generator to run a sump pump”
- Pool Pump Generator Size Calculator“what size generator to run a pool pump”
- Electric Water Heater on a Generator: Honest Math“can a generator run an electric water heater”
- Microwave Generator Size Calculator“what size generator to run a microwave”
- Coffee Maker Generator Size Calculator“how many watts does a coffee maker need on a generator”
- Dishwasher Generator Size Calculator“will a generator run a dishwasher”
- Induction Cooktop & Hot Plate Generator Calculator“generator size for induction cooktop”
- RV Air Conditioner Generator Calculator (13.5K & 15K BTU)“what size generator to run rv air conditioner”
- Camping Essentials Generator Calculator“what size generator for camping”
- Tailgating Generator Size Calculator“what size generator for tailgating”
- Food Truck Generator Size Calculator“what size generator for a food truck”
- Power Tool Generator Size Calculator“what size generator to run power tools”
- Air Compressor Generator Size Calculator“what size generator to run an air compressor”
- Welder Generator Size Calculator (120V & 240V)“what size generator to run a welder”
- Electric Pressure Washer Generator Calculator“can a generator run an electric pressure washer”
No calculator matches that search — try an appliance name like “fridge” or “welder”.
29 calculators, every number sourced
Every page shows running and starting watts as ranges with named sources — manufacturer spec sheets, DOE data and established sizing charts — plus the 120/240V flag and the honest answer, even when it is “this load doesn’t belong on a portable generator”. Readhow the sizing math works, then check your own nameplates before you buy.
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