basic

Home Battery Backup kWh Needed for a Target Runtime Calculator

kWh = (load_W · hours / 1000) / (DoD · η).

Compute the nameplate (rated) kWh of home-battery backup needed to run a load of P watts for H hours, given depth-of-discharge limit (DoD, typical 0.8-1.0 LiFePO₄) and round-trip efficiency η (typical 0.90). Rated_kWh = (P · H / 1000) / (DoD × η). Reports usable kWh, rated kWh, and number of typical 10 kWh battery modules.

Daniel Oh By Daniel Oh
Published Last reviewed 1 min read

Inputs

W
h

Results

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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

Rated kWh = (P·H/1000) / (DoD · η).

In depth

Compute the nameplate (rated) kWh of home-battery backup needed to run a load of P watts for H hours, given depth-of-discharge limit (DoD, typical 0.8-1.0 LiFePO₄) and round-trip efficiency η (typical 0.90). Rated_kWh = (P · H / 1000) / (DoD × η). Reports usable kWh, rated kWh, and number of typical 10 kWh battery modules.