UPS Backup Calculator

Total Load (Watts)

Sum of all devices' power consumption (lights, router, TV, PC...) in watts.

Desired Backup (Hours)

Power Factor (pf)

Typical appliance pf ~0.7–0.95. Lower pf -> higher VA required.

Inverter Efficiency (%)

Usable Battery Depth-of-Discharge (DoD %)

Use ~50% for lead-acid, 80-90% for Li-ion.

System Voltage (V)

Single Battery Nominal Voltage (V)

Single Battery Capacity (Ah)

e.g., 150 Ah, 200 Ah — capacity of one battery.

Existing Number of Batteries (parallel)

If you already have batteries, enter count (0 for new design).

Safety Margin (%)

Extra headroom for surge or future load. Recommended 15–30%.

Tip: measure device wattages from labels or use a plug wattmeter for accuracy.

Result Summary

Detailed breakdown & suggested battery-bank

Ready

Required VA (nominal)

—

Suggested Inverter (VA)

—

Total Energy Required

— Wh

Energy with Safety Margin

— Wh

Required Battery Bank Ah (@ system V)

— Ah

Number of Batteries (suggested)

—

Expected Runtime (with one battery bank)

— hrs

Notes

—

Battery Bank Visual

Series × Parallel layout

Battery bank fill