How long will a UPS last on battery?
Quick answer: This means backup minutes without utility power—not how many years until you replace the UPS. Most stock towers last about 5–20 minutes at typical office loads; VA alone does not set minutes—use real kW. Screen the VA table below, then open the UPS Runtime Calculator → for an instant estimate.
How this entry works
This page is the entry for how long will a UPS last (outage minutes). Roll up load if needed, then jump into the runtime calculator with VA presets—OEM discharge curves still win for procurement.
Quick Start
Next chain steps
Quick Answer and Conclusion
If your target runtime is under 15 minutes, start from load accuracy and battery health first; if your target is 30–60 minutes, verify both load profile and power factor before deciding battery capacity. VA nameplate alone does not set minutes—use real kW. Screen common tower sizes below, then open the UPS runtime calculator VA table.
| UPS size | Typical load | Planning minutes | Next step |
|---|---|---|---|
| 650 VA | ~200 W | ~10–15 min | Run 650 VA |
| 1000 VA | ~300 W | ~8–14 min | Run 1000 VA |
| 1500 VA | ~300–600 W | ~5–18 min | Run 1500 VA |
| 2000 VA | ~900 W | ~6–12 min | Run 2000 VA |
Estimate: Stock internal packs only. For longer minutes, size Ah after load → UPS capacity (kVA) → battery → runtime on the UPS hub workflow.
Recommended Tool Links
- UPS Load Calculator — estimate realistic UPS load from device watts.
- UPS Capacity Calculator — required kVA capacity from load kW (not a watt list).
- UPS Runtime Calculator — convert battery and load data into backup minutes.
- PF & kW/kVA Converter — validate power factor before final runtime decisions.
UPS runtime by scenario
Presets live in the runtime calculator; multi-device guides: UPS applications on hub.
- Starlink, home office, NAS, gaming PC, office cluster — preset loads in the runtime calculator
- UPS for CCTV
- Server rack / IT
Frequently Asked Questions
How long can a UPS usually last during an outage?
Most stock tower packs are designed for short bridge time—often about 5–20 minutes at typical office loads. Actual runtime depends on battery Wh, real load kW, battery age, and temperature. Use the VA table above, then the UPS runtime calculator.
Does “how long will a UPS last” mean battery lifespan in years?
No. This page means backup minutes without power. Calendar VRLA life is often roughly 3–5 years—a different question from outage runtime.
How long will a 1500VA UPS last?
At roughly 300–600 W, many stock 1500 VA towers screen about 5–18 minutes. Open the 1500 VA runtime preset; OEM curves override spreadsheet estimates.
How should I estimate runtime before purchasing a UPS?
Measure or estimate real load kW, define required backup minutes, then run the runtime calculator (and Ah sizing if minutes drive procurement).
What is the difference between runtime sizing and load sizing?
Load sizing sets protected kW; capacity sizing sets required kVA; runtime sizing answers how long batteries last at that load.