What size generator do I need?
Tick what you want to run at the same time. We add up the running watts, then add the biggest start-up surge, because motors like a fridge compressor need a short burst of extra power to start.
What do you want to run?
Tick at least one appliance to see the size you need.
The suggested size adds 20% headroom so the generator isn't running flat out. It assumes everything runs at once but motors don't all start at the same moment.
An electric clothes dryer needs a 240 V supply. Check the generator has a 240 V outlet.
Stay safe
Never run a generator indoors, in a garage or near open windows. Its exhaust contains carbon monoxide, which you can't see or smell and which can kill. To connect a generator to your home's wiring, use a transfer switch fitted by a qualified electrician.
Sources
- Honda Power Equipment, generator wattage estimation guide
- ENERGY STAR Certified Televisions data set (U.S. EPA), for TV power
Typical figures; your appliances may differ. Last checked 15 October 2026.
How it works
Add up the running watts of everything you want on at the same time. That's the power the generator has to supply continuously.
Then add the biggest start-up surge. Anything with a motor or compressor, like a fridge, an air conditioner or a washing machine, needs a short burst of extra power for a second or two when it starts. Heaters, toasters and kettles don't: their running and starting watts are the same.
We only add the single biggest surge, because motors rarely all start at the same instant. Finally we add 20% headroom, so the generator isn't working at its limit.
Example: a fridge, a TV and a microwave
| Fridge running (Honda guide) | 192 W |
|---|---|
| TV running (typical 50–55 inch) | 84 W |
| Microwave running (1,000 W model) | 1,500 W |
| Running watts in total | 1,776 W |
| Biggest extra at start-up (fridge: 1,200 − 192) | + 1,008 W |
| Starting watts needed | 2,784 W |
| Suggested size with 20% headroom | 3,400 W |
Tick the same three items above and you'll get the same answer.
Common questions
What's the difference between running and starting watts?
Running watts are what an appliance draws while it's working. Starting watts, or surge watts, are the short peak a motor needs to get going. A generator's specification lists both, and you need enough of each.
Can a 2,000 W generator run a fridge?
On its own, yes: a fridge needs about 192 W running and 1,200 W for a moment at start-up. Add a 1,000 W microwave and it gets tight: 1,692 W running plus the fridge's 1,008 W surge is about 2,700 W, so the generator may cut out if the fridge starts while the microwave is on.
Do I need an electrician?
To plug appliances into the generator with extension leads, no. To connect a generator to your home's wiring, yes: it needs a transfer switch fitted by a qualified electrician, so power can't flow back into the grid.