Electrical subpanels allow you to use appliances and electronics safely. This cost guide explains the important factors to consider when installing a subpanel.
Electrical Load Calculator: How to Determine Your Home’s Load Factor
Photo: Bill Oxford / iStock / Getty Images
Photo: Bill Oxford / iStock / Getty Images
Highlights
Your home’s electrical load depends on its size and number of appliances.
A 2,000-square-foot home averages 19 to 55 watts.
You can use your home’s electrical bill to calculate load factor.
A licensed electrician near you can also help determine load factor.
Get quotes from up to 3 pros!
Enter a zip below and get matched to top-rated pros near you.
Load factor isn’t just electrician speak—it’s a term that can help you better understand your home’s energy use. Whether you’re trying to trim your electric bill or just curious about how your usage stacks up, calculating your load factor is a smart first step in improving the efficiency of your space. And good news: it’s easier than you think (no engineering degree or electrical license required).
Average Electrical Load Per Square Foot
Electrical demand isn’t one-size-fits-all—different-sized spaces have different needs. Here’s how your home’s electrical load varies by square footage.
| Average Square Footage | Average Electrical Load in Watts |
|---|---|
| 1,000 | 28.5–83 |
| 1,500 | 19–55 |
| 2,000 | 14–41.5 |
| 2,500 | 11–33 |
| 3,000 | 9.5–28 |
| 4,000 | 7–21 |
| 5,000 | 6–17 |
| 6,000 | 5–14 |
How to Calculate Load Factor
Believe it or not, your electric bill is a goldmine of information that can help you calculate your home’s electrical load with just a few key numbers. Don’t worry—no complex math or special tools required. Just grab your latest bill, a calculator, and get ready to crunch a few numbers.
Load factor = Total electricity (KWh) ÷ peak demand (KW) ÷ number of days in billing cycle ÷ 24 hours
Understanding Watts, Amps, and Volts
Since home service panels are measured in amps ranging anywhere from 100 to 400, you’ll need to calculate the amperage of your service panel versus the total wattage of your electrical load.
You’ll also need to factor in an additional safety margin of around 60% to 80%. In other words, you only want your electrical load to make up roughly 60% of your electrical system’s total capacity. Most experts advise that your safety margin should be no higher than 80%.
To perform your calculations, you need to understand the relationship between volts, amps, and watts. Here are the basic formulas:
Watts = Volts x Amps
Amps = Watts / Volts
You can use these formulas to calculate the capacity of your home's overall electrical service. For example, let’s say you’re working with a 150-amp service panel. Since the main service voltage that enters a home is typically 240 volts, the calculation would be:
240 volts x 150 amps = 36,000 watts
80% of 36,000 watts = 28,800 watts
This means that a 150-amp electrical service should not be expected to accommodate an electrical load of more than 28,800 watts at once.
Who to Hire to Determine Load Factor
If you don’t have time to comb through your electrical bill or if you’d rather lean on the expertise of a professional, your local electrician can determine your home’s electrical load factor as well as provide tips for usage. They can also suggest upgrades that can help lighten the load (pun intended) and make your home more efficient when it counts the most.
Frequently Asked Questions
The homeowners guide to electrical services
From average costs to expert advice, get all the answers you need to get your job done.
Before you hire a licensed electrical contractor, you should learn the cost to run electric from the road to your house so you can budget for the project.
Looking to size up your electrical system to cover higher usage and improve efficiency? Use this guide to see the cost to upgrade an electrical panel.
Before hiring a pro, you may be able to fix a short circuit on your own. Learn how to fix a short circuit with our step-by-step DIY guide.
Learn a new skill and find out how to wire a light switch (safely) in your own home. This is one project that’s sure to light up your day.
Knowing how many amps your fridge uses helps monitor your electric bill and ensures you use the proper circuit. Learn how many amps your fridge uses.