Best overall
Westinghouse iGen4500
4,500W start · 3,700W run
Gasoline · Inverter · 52 dBA · remote start · RV-ready TT-30R
Quiet enough for a campground and strong enough to start a 30-amp RV air conditioner.
Find on AmazonWhat size generator to run space heater and fridge?
Short answer
To run space heater and fridge at the same time you need a generator rated for at least 3,700 starting watts — about 2,200 running watts combined, plus the refrigerator / freezer's startup surge. A 4,000W (midsize portable) unit gives comfortable headroom.
Running watts
2,200W
Peak (surge)
3,700W
Minimum generator
3,700W
Recommended
4,000W
Wattage breakdown
| Appliance | Running watts | Starting watts |
|---|---|---|
| Electric Space Heater | 1,500W | 1,500W |
| Refrigerator / Freezer | 700W | 2,200W |
Sizing a generator for space heater and fridge
Together these draw about 2,200 running watts. You don't add every appliance's starting watts, though — only one motor surges at a time. So the generator only has to cover that running total plus the single largest startup surge (the refrigerator / freezer's), which brings the peak to 3,700 watts.
To power the whole set, choose a generator rated for at least 3,700 starting watts. A 4,000W unit leaves comfortable headroom to add more — the calculator below does that math for your exact list.
Size your full appliance list
This page sizes space heater and fridge together. Open the calculator with them pre-selected, then add everything else you plan to power at the same time.
Size a generator for space heater and fridgeRelated
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Find on AmazonFrequently asked questions
What size generator do I need to run space heater and fridge?
To run space heater and fridge together you need a generator rated for at least 3,700 starting watts. We recommend a 4,000W (midsize portable) unit so you have headroom to add other essentials without running the generator at its limit.
How many watts does it take to run space heater and fridge at the same time?
About 2,200 running watts combined, but you must size for the peak: 3,700 watts, which adds the single largest startup surge in the group on top of the running total. Only one motor surges at a time, so you don't add every appliance's starting watts together.
Why isn't it just the two appliances' watts added together?
Because only one motor surges at the instant it starts. You add up everyone's running watts (2,200W here), then add just the single biggest startup surge — the refrigerator / freezer's — to get the 3,700W peak. Adding every appliance's starting watts would badly oversize the generator.