If you’re wondering “how big of a generator do I need?” what you really want to know is how much generator power or total wattage you need. To determine the best generators for home use, refer to the list and select which appliances and systems you want to power. For an exact wattage number, consult your appliance and systems manuals.

 

Remember that if an appliance has a motor, you will need to calculate the total wattage using the formula:

Running wattage (R) + Starting wattage (R x 3) = Total wattage needed 

With this formula, you can figure out the approximate total wattage needs for each appliance with a motor. Items like light bulbs and coffeemakers, however, don’t need an extra boost of power when they’re turned on. For these items, you only need to be concerned about the running wattage. 

Once you have those, a list of items you want to power and the wattages they need, add the numbers together to figure out what size generator would be right for you. The more appliances you want to use, the bigger generator you will need.  

 

Below is a list of approximate running wattage for various household appliances and technology:

• Refrigerator/Freezer: 600 - 800
• Electric Range (one element): 2500 
• Toaster: 1100 - 1700 
• Microwave: 1200 
• Hot Plate: 1250 
• Coffeemaker: 400 - 800 
• Electric Oven: 5000 
• Television: 100 - 350 
• Personal Computer: 500 - 2000 
• Hair Dryer: 1200 - 1500 
• Vacuum: 700 - 1400 
• Space Heater: 1250 
• Table Lamp: 150 

Below is a list of approximate HVAC and system wattage needs:

 

• Electric Furnace: 5000 - 25000
• Heater (radiant): 1300 
• Central Air Conditioning: 2000 - 4000 
• Water Heater: 3000 - 4500 
• Water Pump: 1000 - 2000 
• Window Air Conditioner: 600 - 1500 
• Outdoor Lighting: 500 - 1000 
• Sump Pump: 1500 

 

Note: The power requirements in this guide are general examples and should not be used to calculate specific requirements. Refer to the user manuals that came with your appliances and tools for manufacturer-provided power requirements.

 

Understanding Starting, Running and Surge Wattage

 

The wattage or power your generator needs to produce will depend on the quantity and type of items or equipment you want to run. Before you can calculate your needs, you need to understand what starting wattage, running wattage and surge wattage are. 

 

Your running wattage is the amount of electricity you need to keep the device running. As the name implies, your starting wattage is the amount of electricity you need to start the device. On average, the amount of power you need to start a device is usually three times the amount you need to keep it running. Surge wattage is the most power you can get from your generator. Now that you understand how wattage works, you can figure out how to choose the best generator size for your needs.

 

Safety Tip: Protect your generator and your home with a circuit breaker. If a generator is not using a circuit breaker, it will eventually overload and overheat. If the generator is not shut off once overheated, it could catch fire. 

 

Mathematics of Calculating Generator Sizing

The owner's manuals for most generators include examples of what kinds of structures and devices they can provide power for. However, here is an example of calculating generator sizing yourself.

 

For example, assume you want a generator that will power a small refrigerator. You consult the refrigerator owner’s manual and find that the running wattage for the device is 350 watts. 

 

• Running Wattage (R) = 350 watts
• Starting Wattage (S) = 350 x 3 = 1,050 watts
• Total Wattage (R + S) = 350 + 1,050 = 1400 watts

 

The total wattage you need to run a small refrigerator would be 1400 watts, so you would need a generator that provided at least that many watts. 

 

Tip: For best results, always use a generator that can comfortably handle all your power needs while using no more than 90 percent of its capacity.

 

Energy Consumption Guide

 

The following wattage chart can be used as a guideline to help you determine what type of generator will be best for your needs. Feel free to call in at (888) 670-7699 x-1 and we can personally help walk you through sizing and pairing your application and budget with the appropriate generator. There is no sense in spending more than need be or under equipping yourself for your need. We would be delighted to help!

Minimum and maximum energy consumption is noted, as well as the surge requirements some tools and appliances require for initial start-up.

This information has been compiled from a wide variety of online sources. Please note that these are only estimates. Your tools and appliances may require different wattages depending on a variety of factors. For more accurate wattage requirements you should either look at the Data Plate on the back of your appliances/tools or you could use a wattage meter that will tell you exactly what wattage is required. This wattage chart should just be used as a reference/starting point.

We recommend purchasing a generator with a large enough wattage rating to run all needed items at 50 percent of full generator capacity.

These numbers are averaged from a variety of sources. Numbers may not represent the type of appliances or tools in your home.

APPLIANCE	MIN	MAX	SURGE	VARIABLES
HOUSEHOLD
Air Conditioner - Central	2000	10,000	11,250
Air Conditioner - Room	1,000	1,500	2,000-2,200	BTU rating
Blender	300	400	850
CD Player	35		0
Clock-Electric	3		0
Clothes Washer	425	1,200	2,300
Coffee Maker	600	1,750	0
Computer Monitor	30	250	0
Computer Printer	100	600	0
Computer - Desktop	80	800	0
Computer - Laptop	200	250	0
Dehumidifier	785		0
Dishwasher	700	1,800	2,000
Dryer - Clothes, Electric	1,800	5,400	6,750
Dryer - Clothes, Gas	300	400	0
Dryer - Hair	1,000	1,800	2,000
Electric Blanket	80	200	0
Fan - Ceiling	10	120	0
Fan - Furnace	300	1,000	500 - 2,350	HP of motor
Fan - Portable	10	150	30-450
Fan - Whole House	500		0
Fax Machine	600	800	0
Freezer - Chest	350	600	0	cubic feet
Furnace - Gas	400		0
Furnace - Oil	1,500		0
Garbage Disposal	450		0
Heater - Electric	1,125	1,500	0
Heater - Engine Block	150	1,000	0
Heater - Radiant	1,300		0
Heater - Water, Electric	5,000		0	40-gallon
Heater - Waterbed	400		0
Hot Plate	1,200		0
Iron - Clothes	1,000	1,400	0
Iron - Waffle	1,200		0
Light Bulb - CF	25		0	bulb rating
Light Bulb - Incandescent	60	120	0	bulb rating
Microwave	625	1,500	800-1,700	wattage rating
Oven - Toaster	1,225		0
Pump - Sump	600	1,050	1,300-2,150
Pump - Well	700		0
Radio	50	200	0
Radio - 2-Way	360	960	0
Radio - CB	5		0
Radio - Clock	1	10	0
Range - Electric	2,100	4,500	0
Refrigerator - Energy Star	132	192	1,200
Refrigerator	475	725	2,200	cubic feet
Satellite Receiver	30	250	0
Shaver-Electric	15		0
Slow Cooker	170	270	0
Stereo	250		0
Stereo - Portable	10	30	0
Telephone - Radio	5	150	0	recv. or trans.
Television	65	340	0	screen size/type (LCD, plasma, etc.)
Toaster	800	1,500	0
Typewriter	800	1,500	0
Vacuum Cleaner	200	1,225	0
VCR/DVD/Bluray	25	350	0
APPLIANCE	MIN	MAX	SURGE	VARIABLES
TOOLS
Air Compressor	975	1,500	1,600-4,500	1/2 - 1 HP
Battery Charger	380	5,750	0	amp rating
Bench Grinder - 8 in.	1,400		2,500
Drill - 1 inch	1,000		0
Drill - 1/2 inch	600	750	900
Drill - 1/4 inch	250		0
Drill - 3/8 inch	440		600
Hammer - Demolition	1,260		0
Hammer - Rotary	1,200		0
Heater - Kerosene	400	625	600-1,000	50-150K BTU
Motor - 1/4 HP	600		1,000
Motor - 1/2 HP	875		2,300
Pressure Washer	1,200		3,600	1 HP
Sander - Belt, 3 in.	1,000		0
Sander - Disk, 9 in.	1,200		0
Saw - Band, 14 in.	1,100		0
Saw - Chain, 12 in.	1,100		0	2 HP
Saw - Circular, 7 1/4 in.	900	1,400	2,300	HP rating
Saw - Circular, 8 1/4 in.	1,400		0
Saw - Table, 10 in.	1,800		4,500
Sewing Machine	100		0
Welder - Electric	7,800	9,000	0	100-200 amp
APPLIANCE	MIN	MAX	SURGE	VARIABLES
OUTDOOR/RECREATION
Air Conditioner - RV	1,000	2,000	1,600-3,300	BTU rating
Fence-Electric	2,500		0	25 miles
Fridge - RV	180		0
Garage Door Opener	350	720	600-1,420	HP rating
Heater-Stock Tank	100		0
Hedge Trimmer	450		0
Mower - Electric	1,500		0
Weed Eater	500		0

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