Electric Power Consumption Calculator
This electric power consumption calculator adds up the total draw of multiple devices running at once. Add up the total power draw of multiple devices running at the same time — useful for understanding circuit load, sizing a battery backup or inverter, or just seeing what's really pulling electricity in a room. Shown in watts, kilowatts, and amps, plus what it costs if you add your rate.
Your devices
Total power draw
Add devices to see total power draw.
How this calculator works
Total watts is simply every device's wattage added together. Amps = total watts ÷ the voltage you select. The cost line multiplies total watts by 1 hour of runtime as a quick reference point — for a real cost estimate across your actual daily usage, use the full usage & cost calculator, which lets each device have its own hours per day.
This calculator simply adds the wattage you enter for each device to get a total instantaneous power draw, converts to amps using the standard formula (amps = watts ÷ volts) at the voltage you select, and separately estimates cost using hours of use and your electricity rate. It does not know your home's actual circuit capacity or wiring. Last checked September 2026.
Frequently asked questions
What's the difference between power (watts) and energy (kWh)?
Power is how fast something draws electricity right now, measured in watts, like a speedometer. Energy is how much electricity was actually used over time, measured in kilowatt-hours (kWh), like an odometer. This calculator shows both: the total watts everything draws at once, and the kWh (and cost) that adds up to over a day, month, or year of use.
How do I convert watts to amps?
Amps = watts ÷ volts. Most U.S. household outlets run at 120 volts, while larger appliances (electric dryers, ranges, EV chargers) often run at 240 volts on a dedicated circuit. This calculator does the conversion for you once you select the voltage.
Can I use this to figure out if I'll trip a breaker?
Only as a rough sanity check, not a final answer. A standard 15-amp household circuit is rated for about 1,800 watts at 120V, and a 20-amp circuit for about 2,400 watts, but code and safe practice generally call for not loading a circuit past 80% of its rating for anything running continuously. For an actual circuit or panel decision, consult a licensed electrician rather than relying on this tool.
Why does my total feel higher than I expected?
It's easy to undercount devices that are running in the background, and a few high-wattage items (a space heater, hair dryer, microwave, or window AC) can dominate the total even when everything else in the list is small. Add every device actually drawing power at the same time for an accurate picture.
Related tools
- Electricity Usage & Cost Calculator — per-device hours and monthly cost
- Generator Wattage Calculator
- Appliance Database
- Best Energy Monitors & Smart Plugs — measure real draw instead of estimating it.
- EV Home Charging Cost Calculator — a home EV charger is exactly the kind of high-draw device this page's math is meant for.
This calculator provides estimates based on the figures you enter. It is not a substitute for a licensed electrician's assessment of your home's wiring, circuits, or panel capacity.