This tool will help you determine the minimum size service you need for your new house or feeder size for your sub-panel. This calculation is based off of the optional method in the NEC. Simply input your information in the boxes and click the calculate button. Do not include open porches, garages, or unused or unfinished spaces not adaptable for future use in your square footage. You can also leave out an average sized refrigerator and any countertop appliances (toaster, blender etc.) as these are included in your general kitchen circuits that I have provided a default value for since they are required by NEC. I have also included the default value for a washer outlet (required by NEC). All values (except house square footage and number of space heaters) are in VA. All of your appliances should have the VA listed on their nameplates. For appliances you don't yet have, but need to calculate, see my estimated loads page. If you plan on using a furnace and/or heat pump, but don't have it yet, you will need to get this information from your heating supplier. If you don't know the VA, but know the amps, wattage or voltage of your appliance, calculate the VA here. If you know the horsepower, but not the VA, find it here.


How many square feet is your house? SqFt
Nameplate rating of appliance #1 VA
Nameplate rating of appliance #2 VA
Nameplate rating of appliance #3 VA
Nameplate rating of appliance #4 
VA
Nameplate rating of appliance #5 
VA
Nameplate rating of appliance #6 VA
Nameplate rating of appliance #7
VA
Nameplate rating of appliance #8 VA
Kitchen VA (Use default value if this calculation is for your main service, change to 0 if you're calculating for a sub-panel that won't be feeding a kitchen)
Washer
VA (Use default value if this calculation is for your main service, change to 0 if you're calculating for a sub-panel that won't be feeding a washer)
Electric Furnace load  VA  (If you have more than one furnace, just add their VA together.)
If using space heaters, how many?
( Number of heaters if using individual wall heaters or baseboard heat)
Total load of space heaters
VA ( Add the va of all your space heaters together )
A/C Load VA


Your calculated VA will show here.

Your Calculated Amps will show here.