What is the Right Size Generator for You?
You are looking for a power generator for a specific use. The main consideration is the generator’s wattage capacity, including start-up surge wattage. Other factors are the number of outlets the generator has, what fuel it runs on and if it is portable or stationary. However, the most important factor is wattage output. Let’s calculate what you’ll need.
How Many Watts Will Your Generator Need to Produce?
You will need to add up the wattage of tools, appliances and motors you want to run at the same time. Then select a generator with the running wattage rating to match or exceed the total load. Remember that tools and appliances with electric motors require additional tool/appliance surge wattage at startup that can be double or triple the normal running wattage requirement. Look at the surge watts required and make sure you choose a generator with enough additional wattage to start them. Keep in mind that you typically are not starting more than half of the items at the same time.
Most home appliances and power tools are 120 Volts; larger appliances like electric stoves and clothes dryers may be 240 Volts. Generator power is measured in Watts: Amps x Volts = Watts.
You can use the wattage chart below or our interactive wattage calculator to estimate the wattages of the tools, appliances and motors you will be operating at the same time. Wattages listed below are approximates only; please refer to the tool or appliance itself for specific wattage required.
Wattage Chart
| Category | Appliance | Running Wattage Required | Surge Wattage Required at Startup |
|---|---|---|---|
| Household / RV | Coffee Maker | 1750 | 0 |
| Keurig Coffee Maker | 300 | 1500 | |
| Dishwasher: Cool/Dry | 700 | 1400 | |
| Electric Fry Pan | 1300 | 0 | |
| Electric Range: 8in. Element | 2100 | 0 | |
| 625W Microwave | 625 | 800 | |
| Refrigerator or Freezer | 700 | 2200 | |
| Automatic Washer | 1150 | 2300 | |
| Electric Clothes Dryer | 1800 | 5750 | |
| Furnace Fan (Gas or fuel oil): 1/8 HP | 300 | 500 | |
| Furnace Fan (Gas or fuel oil): 1/6 HP | 500 | 750 | |
| Furnace Fan (Gas or fuel oil): 1/4 HP | 600 | 1000 | |
| Furnace Fan (Gas or fuel oil): 1/3 HP | 700 | 1400 | |
| Furnace Fan (Gas or fuel oil): 1/2 HP | 875 | 2350 | |
| Lights | As indicated on bulb | 0 | |
| Single 60W equivalent CFL bulb | 15 | 0 | |
| Radio | 50-200 | 0 | |
| Sump Pump: 1/3 HP | 800 | 1300 | |
| Sump Pump: 1/2 HP | 1050 | 2150 | |
| 50in LED HDTV | 140 | 0 | |
| 50in LCD HDTV | 300 | 0 | |
| 50in Plasma HDTV | 220 | 0 | |
| RV Air Conditioner: 13,500 BTU | 1500 | 2200 | |
| Room Air Conditioner: 10,000 BTU | 1500 | 2200 | |
| Central Air Conditioner (for 2200 sq. ft. home*) | 10,000 | 11,250 | |
| Small Appliance | 200 | 1700 | |
| Contractor | 8in. Bench Grinder | 1400 | 2500 |
| Pressure Washer: 1 HP | 1200 | 3600 | |
| 7-1/4in. Circular Saw | 1400 | 2300 | |
| Electric Chain Saw: 14in. Bar, 2 HP | 1100 | 0 | |
| 10in. Table Saw | 1800 | 4500 | |
| Drill: 3/8in., 4 Amps | 440 | 600 | |
| Drill: 1/2in., 5.4 Amps | 600 | 900 | |
| Industrial Motors | Split Phase: 1/4 HP | 600 | 1000 |
| Split Phase: 1/2 HP | 875 | 2300 | |
| Capacitor Start Induction Run: 1/3 HP | 720 | 1300 | |
| Capacitor Start Induction Run: 1 HP | 1600 | 4500 | |
| Capacitor Start Capacitor Run: 1 1/2 HP | 2000 | 6100 | |
| Fan Duty: 1/6 HP | 550 | 850 | |
| Farm Equipment | Electric Fence: 25 Miles | 2500 | 0 |
| Milk Cooler | 1100 | 1800 | |
| Milker (Vacuum Pump): 2 HP | 1000 | 2300 | |
| Portable Heater (Kerosene, Diesel Fuel): 50,000 BTU | 400 | 600 | |
| Portable Heater (Kerosene, Diesel Fuel): 90,000 BTU | 500 | 725 | |
| Portable Heater (Kerosene, Diesel Fuel): 150,000 BTU | 625 | 1000 | |
| Battery Charger: 15 Amp | 380 | 0 | |
| Battery Charger: 60 Amp with 250 Amp Boost | 1500/5750 | 0 | |
| Battery Charger: 100 Amp with 300 Amp Boost | 2400/7800 | 0 | |
| Electric Welder: 200 Amp AC | 9000 | 0 | |
| Electric Welder: 230 Amp AC at 100 Amp | 7800 | 0 | |
| Computers / Devices | Desktop | 600-800 | 0 |
| Laptop | 65 | 0 | |
| LCD Computer Monitor | 25 | 0 | |
| Fax | 600-800 | 0 | |
| Laser Printer | 400 | 0 | |
| Inkjet Printer | 15 | 0 | |
| Tablet | 12 | 0 | |
| Cell Phone Charger | 10 | 0 |
*Based on average-sized unit. Central air conditioners differ in wattage requirements; consult owner's manual for specific wattage requirements.
Now, add together the wattage requirements for all the electrical devices that you want to run to determine the minimum continuous wattage, or start at the same time to determine the minimum surge wattage you will need from a generator.
Minimum Recommendations for Typical Home Standby Power (1 kw = 1,000 watts)
Typical Home Standby Power Needs
| Customer Type | Appliance | One Item at a time | Two Items at a time | All Items at once |
|---|---|---|---|---|
| Customer #1 | Lights | 2.4kw | 4.5kw | 6.6kw |
| Color Television | 2.4kw | |||
| Furnace Fan | 2.4kw | |||
| Freezer | 2.4kw | |||
| Refrigerator | 2.4kw | |||
| Sump Pump | 4.5kw | |||
| Customer #2 | Includes Customer #1 and central air | 4.5kw | 6.6kw | 10.5kw |
| Customer #3 | Includes Customer #1 and a well pump | 4.5kw | 6.6kw | 10.5kw |
| Customer #4 | All of the above | 4.5kw | 6.6kw | 13.5kw |