Make a plan for your essentials.
Choose a battery, add your average loads and see an estimated runtime. Example appliance values are editable, not measurements of your home.
Calculating your selected loads…
- Average appliance load
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- Energy after reserve
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- Battery-side draw, incl. losses
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- Capacity for your target
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Startup compatibility is not verified. Check each appliance’s startup demand, the station’s surge specification and individual outlet limits. Average watts alone do not prove compatibility.
See the calculation
Runtime = capacity × (1 − reserve) ÷ (average load ÷ AC efficiency + idle draw).
Required nominal capacity = target hours × (average load ÷ AC efficiency + idle draw) ÷ (1 − reserve).
Efficiency and reserve are fractions in the formula. Battery age, temperature, varying loads and power-save settings can change the actual result.
Use it as a planning estimate.
Measure your real appliances, adjust the assumptions and test the actual equipment before relying on it. The defaults describe AC loads; direct DC use needs different assumptions. This tool is not a design tool for medical equipment, house wiring or other safety-critical backup.
A transparent model
A 1,000Wh battery, 100W constant load, 100% efficiency, zero reserve and zero idle draw gives exactly ten hours. Real systems have losses. Our default reserve and loss assumptions deliberately make that simple result more realistic, but they are not a guarantee.