Home battery sizing calculator
Estimate nominal battery energy and an inverter power allowance from daily, evening or appliance loads, autonomy, depth of discharge and your efficiency assumptions.
Energy 0 to 1 million kWh per reference period; evening period above 0 to 24 hours; autonomy above 0 to 8,760 hours total, including day conversion; peak 0 to 1 million kW. Positive depth of discharge, round-trip efficiency and retained-capacity factors up to 100%; inverter headroom 0 to 100%. Appliance mode: up to 100 rows, 100,000 characters, quantity 1 to 10,000, power 0 to 1 million W and duty-cycle time 0 to 24 h/day. JSON report, results CSV, battery-budget CSV and appliance CSV. Choose daily energy, evening energy or an appliance list in the settings. Appliance rows are name, quantity, running W and hours per day. Up to 1,000,000 characters. Review the settings before running.
Your result
How to use Home battery sizing calculator
- Choose daily energy, evening energy or an appliance list.
- Enter load energy and its reference period, or appliance name, quantity, running W and hours per day.
- Enter autonomy in hours or days, depth of discharge, round-trip efficiency and a separate peak load.
- Review the assumptions and energy budget, then download the JSON report and complete CSV files.
Useful next steps
Energy and power are separate
A battery stores energy in kWh; an inverter supplies power in kW. Required delivered energy scales the average load in your stated reference period to the autonomy hours. The entered peak must cover the average and each active individual appliance, but does not need to equal every appliance running together.
Daily and evening periods
Daily energy and appliance lists represent 24 hours. Evening energy uses your entered evening hours. Energy is spread uniformly over that period when scaled to autonomy; longer evening autonomy repeats that average rather than simulating the rest of the day. Use daily data when that is the intended load profile.
A conservative full-cycle budget
Nominal storage divides delivered energy by depth of discharge, full-cycle round-trip efficiency and the entered temperature/age retained-capacity factors. Full-cycle efficiency is a conservative planning allowance, not a one-way discharge prediction. Enter 100% retained capacity to apply no temperature or ageing derating. Startup duration, battery discharge current, charging supply and installation protection need separate checks.