Battery Backup Calculator

Calculate UPS runtime and required battery capacity for your equipment.

Load Requirements

Total Load (Watts)

Sum of all equipment you want to protect

Desired Runtime (minutes)

UPS Rating (VA)

Inverter Efficiency (%)

Typical: 80-90% for consumer UPS

Battery Voltage

Battery Capacity (Ah)

Number of Batteries

Depth of Discharge (%)

30%50%80%

50% recommended for longest battery life

Estimated Runtime

5.5 min

0.09 hours at 500W load

Total Capacity108.0 Wh

Usable (50% DoD)54.0 Wh

Effective (w/ efficiency)45.9 Wh

Capacity Needed588.2 Wh

Battery Ah Needed49.0 Ah

Batteries Needed6 x 9Ah

UPS Capacity900W

Load Percentage55.6%

Recharge Time~5.0 hrs

Common Device Wattages: