Battery Runtime Calculator
Use this when you already know the battery capacity and the wattage of the device you want to run.
Last updated: May 2026
Buying and sizing notes
- If you are comparing batteries, compare watt-hours, not just amp-hours, unless voltage is the same.
How to use this estimate
What this includes
- The required inputs shown on this page
- common planning assumptions
- optional advanced adjustments where provided
What it does not include
- site-specific professional design
- local code approval
- manufacturer-specific requirements
- installation quality
Common mistakes
- Leaving a required input at the default when your situation is different
- ignoring product labels or ratings
- treating the estimate as an exact final answer
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