Check off the appliances you need to power, and we'll tell you exactly what size generator to buy — accounting for both running watts and motor starting surges.
Check every appliance you want to run at the same time during a power outage or job site use.
☑️ Check appliances above to see your generator size recommendation.
Every generator has two wattage ratings, and mixing them up is the #1 mistake people make when buying a generator. Here's what they mean:
The continuous power the generator produces and the appliance consumes during normal operation. Add up the running watts of everything you want to run simultaneously — this is your baseline load.
Motors — refrigerators, AC units, pumps — need a burst of extra power to start spinning. This surge lasts only 2–3 seconds, but your generator must be able to supply it. Starting watts are typically 1.5–3× running watts for motor loads.
How this calculator handles it: We add your total running watts, then add the largest single starting surge on top (since only one motor starts at a time). The result is your peak starting demand — the number your generator's rated starting capacity must meet or beat.
Running and starting watts for 40+ appliances, organized by category. Print it and keep it with your generator.
Complete 2025 guide covering power outages, camping, job sites, portable vs. standby, and common use cases.
Step-by-step walkthrough with a real worked example so you understand the math, not just the result.
Six picks across every price tier — budget, mid-range, premium, dual-fuel, inverter, and heavy-duty.