UPS Sizing Calculator
UPS Capacity Sizing
Calculate required UPS VA rating for your equipment
UPS Runtime Estimation
Estimate battery runtime based on UPS specs and load
Formula
UPS VA = Total Watts / Power Factor × (1 + Growth%) | Runtime = Battery Wh / (Load W / Efficiency)
Frequently Asked Questions
How do I size a UPS for my equipment?
Add up the wattage of all equipment to be protected. Divide by the UPS power factor (typically 0.8) to get VA. Add 25% for growth. Choose a UPS rated at or above this value. For critical systems, consider N+1 or 2N redundancy.
What is the difference between VA and Watts for UPS?
VA (volt-amperes) is apparent power, W (watts) is real power. They differ due to power factor: W = VA × PF. A 1500 VA UPS with 0.8 PF can deliver 1200W. Always check both the VA and watt rating when comparing UPS units.
How long will a UPS run my computer?
A typical desktop computer draws 200-400W. A 1500VA/900W UPS with internal batteries typically provides 5-15 minutes of runtime at full load. At 50% load, runtime approximately doubles. External battery packs can extend runtime to hours.
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