Generator wattage chart
A refrigerator plans at 700 running watts and 2,200 at compressor start. A 1/2 HP sump is 1,050 / 2,150. A gas furnace blower is 800 / 2,350. The tables below are the full planning chart every calculator on this site uses; the last column is the portable class that covers that appliance alone with 20% headroom.
Numbers come from the conservative end of manufacturer wattage charts (Champion, Lowe's/Honda worksheets). They are planning figures, not a promise about your unit. Linked rows open a page with nameplate ranges by type and combo math for what fits alongside.
Keep-alive basics
| Appliance | Running | Starting | Class alone |
|---|---|---|---|
| Refrigerator | 700 W | 2,200 W | 2,200W inverter |
| Chest or upright freezer | 500 W | 1,500 W | 2,200W inverter |
| Lights (10 LED bulbs) | 100 W | no surge | 2,200W inverter |
| Wi-Fi router + modem | 25 W | no surge | 2,200W inverter |
| Phone + laptop chargers | 75 W | no surge | 2,200W inverter |
| TV | 200 W | no surge | 2,200W inverter |
| CPAP machine | 60 W | no surge | 2,200W inverter |
Pumps and hot water
| Appliance | Running | Starting | Class alone |
|---|---|---|---|
| Sump pump, 1/3 HP | 800 W | 1,300 W | 2,200W inverter |
| Sump pump, 1/2 HP | 1,050 W | 2,150 W | 2,200W inverter |
| Well pump, 1/2 HP | 1,000 W | 2,100 W | 2,200W inverter |
| Well pump, 1 HP | 2,000 W | 4,000 W | 3,500W portable |
| Electric water heater | 4,500 W | no surge | 6,500W portable |
Heating and cooling
| Appliance | Running | Starting | Class alone |
|---|---|---|---|
| Furnace blower (gas heat) | 800 W | 2,350 W | 3,400W inverter |
| Space heater | 1,500 W | no surge | 3,400W inverter |
| Window AC, 10,000 BTU | 1,200 W | 2,400 W | 3,400W inverter |
| Central AC, 3 ton | 3,500 W | 6,000 W | 5,000W portable |
Kitchen and laundry
| Appliance | Running | Starting | Class alone |
|---|---|---|---|
| Microwave | 1,400 W | no surge | 2,200W inverter |
| Coffee maker | 1,000 W | no surge | 2,200W inverter |
| Electric range, one burner | 1,500 W | no surge | 3,400W inverter |
| Dishwasher | 1,500 W | no surge | 3,400W inverter |
| Washing machine | 1,000 W | 2,300 W | 3,400W inverter |
| Electric dryer | 5,400 W | 6,750 W | 7,500W portable |
Garage and EV
| Appliance | Running | Starting | Class alone |
|---|---|---|---|
| Garage door opener | 550 W | 1,100 W | 2,200W inverter |
| EV charging, level 1 (120V) | 1,400 W | no surge | 2,200W inverter |
| EV charging, level 2 (240V) | 9,600 W | no surge | 12,000W portable |
How to use this chart
Write down everything you will run at the same time. Sum the running column. Add the single largest (starting minus running) difference for the motors on the list. That peak is what the generator has to survive for a second; the running sum is what it has to hold for hours. The wattage picker does that arithmetic for you, and the starting vs running watts guide explains why the spike exists.
Resistive loads (space heaters, water heaters, coffee makers, dryers on heat) have no start surge: running and starting are the same number. Compressors and pumps are the ones that double or triple for a second, and they are the ones that stall a generator sized to running watts alone.
Questions people ask
What is a generator wattage chart?
A table of planning numbers for how many running watts and starting watts common appliances draw, so you can size a portable or inverter generator before you buy. Ours is the same data table the wattage picker and every per-appliance page on this site use, not a separate copy.
Running watts or starting watts: which sizes the generator?
Both. Add running watts for everything that will be on at once, then add the single largest (start minus run) gap for the biggest motor starting on top. The generator needs a peak rating above that total and a rated running figure about 25% above the running total so it sits under 80% continuous.
Why does the chart number disagree with my nameplate?
Charts lean high on purpose. A new fridge often runs under 400W while the planning row says 700; the garage unit from 2003 may hit the chart or beat it. Amps on the nameplate times volts is the real running figure. Where they disagree, believe the nameplate.
Can I run everything in a group at once on the class in the last column?
No. The last column is the class for that appliance alone. Stack fridge + furnace + sump and the peaks add up; use the wattage picker for the real list, or the combo tables on each appliance page.