Off-Grid Load Calculator
Add up your off-grid appliances to find daily energy use, peak power and peak current at your system voltage \u2014 to size your inverter, battery and solar. Calculates in your browser.
Daily energy
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Show the math
Daily energy adds up each load's watt-hours; peak power assumes everything runs at once:
daily Wh = Σ (watts × hours × qty)
peak A = Σ (watts × qty) ÷ voltage
Size your inverter to the peak watts and your battery/solar to the daily kWh. Quantity defaults to 1 if left off. All math runs in your browser.
What this does
An off-grid load calculator adds up your appliances to find daily energy use, peak power, and peak current at your system voltage — to size the inverter, battery, and solar.
How to use it
- List each appliance with its watts.
- Add hours per day and quantity.
- Read the daily kWh total.
- Read peak watts and current.
How it works
Size the inverter to your peak watts (everything on at once) and the battery and solar to your daily kWh.
daily Wh = watts × hours × qty; current = watts ÷ volts
Understanding your result
Size the inverter to your peak watts, everything that might run at once, but size the battery and solar to your daily kilowatt-hours, which is total consumption over time. They answer different questions, so do not confuse them. Watch phantom loads too, since small always-on devices quietly add up over 24 hours and can dominate a modest off-grid budget.
Example
A 60 W load run 5 hours uses 300 Wh a day.
Sources & methodology
Last updated .
Frequently asked questions
How do I size an off-grid system?
Size the inverter to your peak watts (everything running at once) and your battery and solar to your daily kWh total.
What format are the loads in?
One appliance per line: name, watts, hours per day, quantity. Quantity defaults to 1 if you leave it off.
Is my data stored?
No. Everything is calculated locally in your browser.
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