UPS Capacity Calculator
Size the required UPS capacity in kVA using load, power factor, surge allowance, future growth margin, and redundancy policy.
Quick UPS Capacity Calculator
Quick mode uses default surge 1.2x, growth 20%, utilization 80%, and no redundancy.
Advanced UPS Capacity Calculator
Sizing Result
Result explanation uses practical assumptions and should be validated with project-specific constraints. This is an engineering estimate, not a final compliance design.
Formula
Required kVA = (Load kW / PF) × Surge Factor × (1 + Growth Margin) / Utilization Target × Redundancy Factor
Where Utilization Target is entered as percentage (for example, 80% becomes 0.8).
Example
For 3 kW load, PF 0.8, surge 1.2, growth 20%, utilization 80%, and no redundancy:
Required kVA = (3 / 0.8) × 1.2 × 1.2 / 0.8 × 1.0 = 6.75 kVA, so select the next standard size: 10 kVA.
Frequently Asked Questions
What is the difference between UPS capacity and runtime?
Capacity (kVA) determines how much load the UPS can support at a moment, while runtime depends on battery energy and load profile.
Why should I keep utilization below 100%?
Running at full utilization leaves no operational headroom. Engineering practice often targets 70-85% for reliability and future changes.
When should I use N+1 or 2N?
Use N+1 for high-availability sites needing reserve capacity after one module failure. Use 2N for mission-critical environments requiring full mirrored power paths.
Related Tools
UPS Hub
Browse full UPS workflows and guides in the hub page: UPS Calculators Hub.