Appliances & Utilities calculator
What Home Battery Size Do I Need?
Use critical continuous load, desired backup hours, usable battery fraction to find home battery energy and inverter requirement.
Enter your measurements
What Home Battery Size Do I Need uses critical continuous load, desired backup hours, usable battery fraction and the other configured measurements to return home battery energy and inverter requirement with a formula written specifically for this tool.
- Critical continuous load — Required
- Desired backup hours — Required
- Usable battery fraction — Required
- Inverter efficiency — Required
- Peak load — Required
Home battery energy and inverter requirement
Enter the measurements above to calculate home battery energy and inverter requirement.
How the calculation works
V9 calculation: requiredEnergyWh=criticalLoadWatts×backupHours/(usableFraction×inverterEfficiency); minimumInverterWatts=peakLoadWatts. The result is reported as home battery energy and inverter requirement.
Worked example
Example: Critical continuous load = 500 W; Desired backup hours = 4 h; Usable battery fraction = 80%; Inverter efficiency = 90%; Peak load = 1000 W. Result: Required Energy Wh = 2777.78 Wh; Minimum Inverter Watts = 1000 W.
Before you decide
Recheck the limiting measurement before purchase or installation. This page calculates the stated geometry or quantity only; product-specific construction or installation details can still affect the final choice. For what home battery size do i need, the limiting result on this page is home battery backup size.
Direct measurement/geometry calculation. No external reference is required for the arithmetic itself; the result is derived only from the user-entered measurements and the formula stored in calculationLogicJson.
Frequently asked questions
What does the Home Battery Size calculator tell me?
It returns home battery backup size from the measurements entered on this page. The calculation is specific to home battery size, so the result should be compared with the exact product or specification you are considering.
Which measurements should I take for home battery size?
Measure critical continuous load, desired backup hours, usable battery fraction, inverter efficiency, peak load. Use clear, usable dimensions rather than nominal room or product labels.
Should I round the home battery backup size?
Keep the calculated value for comparison, then choose a real product that meets or stays within the returned home battery backup size while allowing for the clearances, tolerances or ratings shown by its manufacturer.