Size my backup

Tools

Calculators and data for sizing backup power for your home. Each figure lists its source.

Available now

All free, no account needed.

  • Runtime calculator

    Choose the appliances you need in an outage and how long each one runs. See the total load, the startup peak, how many hours each battery size lasts, and what size power station or generator fits.

  • Backup cost comparison

    Puts a power station, a portable generator, a standby generator and a home battery side by side for your load: price, installation, fuel per outage hour, upkeep and the cost over 10 years.

  • Appliance watts

    Running watts, startup watts and average daily draw for 12 appliances people keep on in an outage. Each appliance has its own page with sources.

In the works

These pages aren't live yet. We'll link each one here when it is.

  • Generator size calculator

    Find the portable or standby generator size that runs the circuits you pick, including the surge when motors start.

  • Power station spec table

    A filterable table of the main power stations, with capacity, output, battery chemistry, cycle rating, weight and price per Wh.

  • Utility outage data

    How often each US utility loses power and for how long, from the EIA-861 reliability data (SAIDI and SAIFI).