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UPS Runtime Calculator
Estimate how long your UPS batteries will power your critical load during an outage. Works with APC, Eaton, Vertiv, Tripp Lite, Mitsubishi and most commercial UPS systems.
1 Your Configuration
Defaults match industry standard sizing: 92% UPS efficiency, 80% usable DoD, 80% end-of-life capacity (VRLA replacement threshold).
2 Estimated Runtime
At your current load
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min
Engineering estimate · ±15–20%
Total Load
0 W
Battery Capacity
0 Wh
Recommended UPS for 15-minute runtime
Required UPS rating
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Battery capacity required
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Phase configuration
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Matching models we service
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Important:
This calculator provides an engineering estimate only. Actual runtime depends on battery age, temperature, discharge rate curve, load profile, and UPS-specific derating. For mission-critical facilities (data centers, hospitals, telecom), always validate with a load-bank test or manufacturer runtime chart. GDF offers free on-site runtime assessments across Quebec and Ontario.
UPS Runtime — Frequently Asked Questions
How accurate is this runtime calculator?
This calculator applies the industry-standard runtime formula with a Peukert correction (k=1.20) for high-rate VRLA discharge — something most free online calculators skip, which is why they overestimate runtime by 50-100% at short discharge times. Our defaults are conservative: 92% UPS efficiency, 80% usable depth of discharge, 80% end-of-life capacity. Expected accuracy is ±15-20% vs a real load-bank test. The largest remaining sources of deviation are temperature (cold rooms reduce runtime further), individual battery condition, and manufacturer-specific discharge curves under 2 minutes.
Why is my actual runtime shorter than the calculator predicts?
The three most common causes are aging batteries (VRLA batteries lose capacity starting at year 3 and should be replaced at 80%), cold room temperatures (a 10°C drop can cut runtime by 20%+), and higher-than-expected load due to IT growth. If your UPS is alarming or delivering noticeably less runtime than before, battery replacement is almost always the cause.
What’s the difference between kVA and kW?
kVA (apparent power) is what the UPS is rated to deliver; kW (real power) is what your equipment actually consumes. They’re related by the power factor. Modern IT equipment with power factor correction runs at 0.9–1.0 PF, so a 10 kVA UPS delivers about 9–10 kW. Older equipment and motor loads can have lower PF (0.7–0.8), meaning the UPS kW capacity is reduced. Always size your UPS by the kW rating, not kVA alone.
How long should a UPS run during an outage?
Industry standard runtime targets: 5–10 minutes for server rooms with generator backup (enough time for generator cutover), 15–30 minutes for sites without a generator (graceful shutdown), and 30–60+ minutes for hospitals, telecom facilities, and critical life-safety systems. Most Canadian data centers and hospitals require 15 minutes minimum at full load, with the generator expected to start within 30 seconds.
Can I extend my UPS runtime by adding batteries?
Yes — most commercial UPS systems (APC Smart-UPS SRT, Eaton 9PX, Vertiv Liebert GXT5, Mitsubishi 9900 series) support external battery modules (EBMs) or additional battery cabinets. Adding strings in parallel roughly doubles runtime per string. However, the UPS charger must be sized for the larger battery bank — GDF can verify compatibility before you buy batteries.
Do you service discontinued UPS models?
Yes. We actively service end-of-life and discontinued UPS systems that the original manufacturer no longer supports: APC Galaxy 3500, Symmetra PX, Smart-UPS VT; Eaton Powerware 9315, 9390, 9155; Liebert NX, NXC, NXL; Mitsubishi 9800/9900; and many more. These legacy systems are often the most critical to service because parts and support are scarce. Contact support@gdftech.com with your model and serial number for a service quote.
