How do you calculate transformer kVA from load current?
For a three-phase load, kVA = voltage × current × 1.732 ÷ 1,000. For a single-phase load, kVA = voltage × current ÷ 1,000. Enter your load current and system voltage and the calculator does both, then applies any growth margin you specify.
What are the standard transformer sizes?
Common three-phase distribution sizes run 15, 30, 45, 75, 112.5, 150, 225, 300, 500, 750, 1,000, 1,500, 2,000, 2,500, 3,000, 3,750, and 5,000 kVA. Single-phase sizes run 5, 10, 15, 25, 37.5, 50, 75, 100, 167, 250, and 333 kVA. The calculator rounds your load up to the next standard size.
How much headroom should I add for future load growth?
A common practice is 20–25% spare capacity for commercial service equipment, but the right margin depends on your load mix, diversity, and expansion plans. Continuous loads also require sizing per NEC 450.3 and related rules — confirm with your engineer.
Does kVA depend on power factor?
No — kVA is independent of power factor, which is why transformers are rated in kVA. Power factor matters for real power (kW = kVA × PF) and for current draw of a fixed kW load: a lower PF pulls more current for the same kW.
Can you quote the transformer this calculator recommends?
Yes — Veridian Electric supplies UL-listed dry-type and pad-mounted transformers sourced to your exact specification from our manufacturer and supply-partner network. Send the recommended size with your request and you will have a firm quote within one business day.
