How many watts does a space heater use
While it runs, a space heater draws 750 to 1,500 W, and it has no starting surge. The smallest portable able to run it is rated at 2,000 W.
Watts for running and starting
| Load | Running | Starting |
|---|---|---|
| Space heater | 750 to 1,500 W | no surge |
The source is the Champion wattage chart, 04-17-26. Your own space heater's nameplate lists the exact figure in watts or amps. Multiply amps by 120 V. For a load, such as a well pump, on a two-pole breaker, use 240 V only.
Smallest generator able to start it
Any generator has to handle 1,500 W at 80% of its rating or less. At 2,000 W, the smallest common portable size handles both jobs with room to spare. Every other load adds its running watts to that same generator.
Other loads along with a space heater
| Space heater plus | Running | Peak at a start | Smallest portable |
|---|---|---|---|
| lights, TV and the router | 2,070 W | 2,070 W | 3,000 W |
| a freezer and lights | 2,150 W | 2,650 W | 3,000 W |
| a 1/2 hp sump pump and lights | 2,700 W | 3,800 W | 3,500 W |
| a microwave | 2,700 W | 2,700 W | 3,500 W |
| a 1 hp well pump | 3,500 W | 5,500 W | 5,000 W |
| a window AC, 10,000 BTU | 2,700 W | 3,900 W | 3,500 W |
The running watts stack up, and just the biggest motor start lands on top of them. A portable's starting output is about 25% higher than its running rating. The appliance wattage chart lists every load.