The Battery / BESS Sizing Calculator tells you how large a battery storage system needs to be for a given load.
You enter your load (in kW), how many hours of backup you need, and your battery’s key characteristics — depth of discharge, round-trip efficiency, inverter efficiency, and a design margin. The tool then calculates:
- Usable capacity — the energy you can actually draw from the battery
- Nameplate capacity — the total rated size you need to buy (in kWh and amp-hours)
- Discharge power and C-rate — how hard the battery has to work
- Recharge energy and charge power — what it takes to refill the pack
It automatically accounts for the losses and reserves that make a real battery bigger than the load alone suggests. A live diagram shows the energy flow, and a Learn tab explains the concepts and formulas behind the numbers.
