UPS Runtime Calculator
Estimate how long your UPS will keep your equipment running during a power outage.
Enter UPS VA rating and total load watts.
Estimated UPS Runtime
UPS runtime depends on the battery capacity and the connected load.
Approximate formula:
Runtime (min) ≈ (UPS Battery Watt-Hours × Efficiency) / Load Watts
VA to Watts conversion:
Watts = VA × Power Factor
Typical UPS power factor: 0.6 (basic) to 0.9 (high-end)
Common UPS sizes and approximate runtimes at half load:
| UPS Rating | Battery (Wh) | Half Load Runtime |
|---|---|---|
| 350 VA | ~35 Wh | ~10 min |
| 550 VA | ~55 Wh | ~15 min |
| 750 VA | ~75 Wh | ~18 min |
| 1000 VA | ~120 Wh | ~25 min |
| 1500 VA | ~200 Wh | ~30 min |
| 3000 VA | ~500 Wh | ~40 min |
Common device power consumption:
- Desktop computer: 200–500 W
- Monitor (24"): 25–50 W
- Router/modem: 10–20 W
- NAS (4-bay): 40–100 W
- Gaming PC: 400–800 W
Note: Runtime decreases significantly as load approaches maximum capacity. Never load a UPS above 80% of its rated capacity.