UPS Runtime Calculator
The UPS runtime calculator estimates how long a UPS will carry its load during a power outage. Enter the load in watts, the battery capacity in amp-hours, the battery voltage, and the inverter efficiency.
The calculator converts battery capacity to watt-hours, accounts for inverter losses, and returns the estimated runtime at your current load plus a worst-case figure at 80% load - the two numbers you need when planning how much time you have for a graceful shutdown.
UPS Runtime Calculator
Estimate how long your UPS will run under load.
Enter values above to see results.
Frequently Asked Questions
How is UPS runtime calculated?
Convert battery capacity to watt-hours (amp-hours x voltage), multiply by inverter efficiency (typically 85-95%), and divide by the load in watts to get hours of runtime. Lower loads and larger batteries both extend runtime.
Why does runtime drop so much as load increases?
Battery capacity is fixed, so runtime is inversely proportional to load: doubling the load roughly halves the runtime. Real batteries also lose capacity as they age and as discharge current rises.
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