Start with what needs to keep working.
Practical steps for determining the right capacity based on critical loads, growth, and real operating conditions rather than marketing claims.
The Short Version
- List every device that must stay on during an outage.
- Record the watt or VA draw of each (nameplate or measured).
- Add a realistic growth margin.
- Match the total to a UPS capacity that leaves headroom, not a unit that runs at its limit.
Start with the load, not the product
Sizing begins with what must keep working. Identify critical loads first. Non-critical loads can be left off the UPS or moved to a different power path.
Account for growth and real conditions
Plan for added equipment and for conditions that reduce available capacity. A unit that is sized exactly to today’s load leaves no margin for change.
Verify with manufacturer data
Use manufacturer runtime and capacity references to confirm the selection. Runtime charts and sizing tools remain planning aids; site measurement and load testing remain the final check where the application is critical.