Home Backup Essentials generator calculators
When the power goes out, the question is never "can I run everything" — it is "which loads matter, and what size generator covers them together". These calculators size the loads people actually protect in an outage: the refrigerator and freezer full of food, the internet connection, medical devices, and the everyday appliances that make a blackout livable. Each one shows running and starting watts as sourced ranges, because a compressor that sips 700W while running can demand three times that for the half-second it starts. This category matters most in the run-up to hurricane season (the Atlantic basin peaks in early-to-mid September): the households that size and test a generator in July run their essentials calmly in September, while the households that wait are shopping a picked-over hardware-store shelf the week landfall is forecast.
Pick your calculator
Refrigerator Generator Size Calculator
What size generator runs a refrigerator? Sourced running and starting watts (typical 700W running, 2,200W surge), 25% headroom math, and a size-class answer.
Open calculator →Chest Freezer Generator Size Calculator
Generator sizing for a chest freezer: sourced running watts (~500W) and starting surge (~1,500W), the 25% headroom rule, and which generator class you need.
Open calculator →TV, Wi-Fi & Lights Generator Calculator
Watts to keep the TV, Wi-Fi router and LED lights on in an outage — an itemized ~250W bundle with no surge allowance, and the size class it fits.
Open calculator →Home Office Generator Size Calculator
Keep working through an outage: itemized watts for laptop, monitors, router and lighting (~300W), the laser printer trap, and which generator class covers it.
Open calculator →CPAP & Medical Device Generator Calculator
Backup power for a CPAP: real watt draw (30–60W, ~150W with heated humidifier), why a battery backup often beats a generator — safety questions first.
Open calculator →Dehumidifier Generator Size Calculator
Dehumidifier generator sizing: sourced running watts (300–700W, ~500W typical), ~900W starting surge, and the class for post-storm basement drying.
Open calculator →Garage Door Opener Generator Calculator
Garage door opener on generator power: sourced watts (~720W running, ~1,400W starting), the manual-release alternative, and which generator class covers it.
Open calculator →Washing Machine Generator Size Calculator
Washing machine generator sizing: ~1,150W running, ~2,250W starting surge from sourced charts, cold-wash strategy — the dryer is a different story.
Open calculator →EV Charging From a Generator: Honest Calculator
Can a generator charge an EV? Level 1 (1,440W) works but adds ~3–5 miles of range per hour; Level 2 needs 240V and 7,700W+.
Open calculator →
Which calculator should I use?
Start with the refrigerator and chest freezer calculators — food spoilage is the most expensive outage cost for most households, and both are motor loads with big starting surges. The TV, Wi-Fi and lights bundle covers the small electronics people forget to count. If anyone in the house uses a CPAP or other medical device, read that page first: for life-critical equipment a battery backup is often the better first line than any generator. If your outage risk comes with rain, the sump pump calculator in Water & Pumps belongs in this same plan — flooded basements and dead power arrive together, and the two pre-built storm scenarios below combine sump-pump and essentials math into one worked example. For everything combined, use the multi-appliance builder on the home page or start from a pre-built outage scenario.
Running several of these at once? The multi-appliance builder adds them up with the staggered-start surge math, and the outage scenarios cover the common combinations pre-built.