UPS Runtime Calculator — Estimate Backup Time by Load
Tell us your equipment load and required runtime. We'll show every UPS in our catalogue that fits — with the estimated runtime at your specific load.
Find a UPS that fits your load
Drag the slider to your equipment's wattage. Pick a minimum runtime. We'll rank the UPS units in our catalogue by how well they match.
Power factor 0.80 VA × power factor = real load in watts. Default 0.8 covers most modern IT gear.
Advanced settings
Recommended UPS units
Sorted by best fit. UPS units sized to run at 60-80% of capacity get top placement.
No UPS in our catalogue meets that load and runtime requirement. Try a smaller load, a shorter runtime, or contact a specialist for an engineering assessment.
Complete your setup
Accessories that pair with the recommended UPS. Model-specific accessories are listed on each product page.
UPS Runtime Calculator — enter your UPS capacity (VA or kVA) and connected load (watts) to estimate expected backup time during a power outage. Useful for sizing replacement batteries, planning generator-bridge time, and validating manufacturer-specified runtimes against real-world load.
How to Use the Calculator
- Find your UPS capacity — printed on the UPS nameplate, typically in VA (e.g. 1500VA) or kVA (e.g. 10kVA). Convert if needed: 1 kVA = 1000 VA.
- Estimate your connected load in watts — add up the wattage of every device plugged into the battery-backup outlets. Servers, monitors, switches, NAS, etc. Most equipment lists draw on the back-panel sticker.
- Enter both values above and the calculator returns expected runtime at that load. As a rule of thumb: full load = 5–15 minutes; half load = 15–40 minutes; quarter load = 1+ hour on standard internal batteries.
Sizing Tips
- Add 25% headroom to your real load when sizing a new UPS — leaves room for equipment changes and prevents overload trip.
- Match VA to wattage carefully: a 1500VA UPS typically delivers only ~900W continuous (power factor ~0.6–0.7 for older units, ~1.0 for modern Smart-UPS / Eaton 9PX). Wattage is what matters for sizing real loads.
- For longer runtimes, add an external battery cabinet (most online UPS units support this) rather than oversizing the UPS frame itself.
- For mission-critical loads, size to bridge generator startup (typically 8–12 seconds) plus a defensive buffer — the UPS is the bridge, not the long-duration backup.
- Battery age matters: by year 4 a VRLA battery typically delivers ~70% of nameplate capacity. Schedule replacement at year 3.5–4 in 24/7 deployments — see our UPS battery replacement service.
Related Resources
- UPS FAQ — single-phase vs three-phase, medical-grade, sizing
- UPS Battery FAQ — lifespan, replacement, compatibility
- Battery Technical FAQ — SLA / VRLA basics, V/Ah matching
- All UPS Replacement Batteries — OEM cartridges (APC RBC, Eaton 744-series, Vertiv GXT, Tripp Lite RBC) and AGM equivalents
- Line-Interactive vs Online UPS — topology decision guide
- Single-Phase Smart UPS Comparison — APC vs Eaton vs Vertiv selection
Need Help Sizing Your UPS?
If your environment is mission-critical — healthcare, data centre, mining, government IT — a calculator is a starting point but a proper site survey beats it. Our team handles full UPS installation and consulting with site assessment, load analysis, and code-compliant deployment across Canada. Contact us for a consultation — or call 438-881-3363.
Need more backup time than the numbers show? See our buyer's guide to extended runtime UPS and rackmount models.
Talk to a Canadian UPS specialist
Send us your equipment list and we'll spec the right UPS, including extended battery pack options if you need longer runtime than a single UPS can deliver.