For study estimates only, not engineering design
Transformer kVA calculator helps you size quickly during budgeting or early design. Use either kW + PF or V/I + PF, select 1-phase or 3-phase (√3·V·I), and the tool computes load kVA. Add a headroom factor (e.g., 1.25) to get a suggested standard rating—rounded up to common sizes—before you dive into temperature rise, environment, harmonics, and code requirements.
Transformer kVA Quick Estimator
On the Texas Journeyman exam
Where this calculation shows up
On the PSI Texas Journeyman exam this is part of the Calculations part: Transformers. That part has 26 questions in 110 minutes, and you need 70% on it on its own.
Try an exam-style calculation (our own numbers): A three-phase 208 V load draws 100 A on each line. What is the load in kVA?
- A. 12.0 kVA
- B. 20.8 kVA
- C. 36.0 kVA
- D. 62.4 kVA
Show the answer
C. 36.0 kVA. kVA = 1.732 x V x I / 1,000 = 1.732 x 208 x 100 / 1,000 = 36.0 kVA. Without the 1.732 you get the single-phase answer, 20.8 kVA.
Try 70 free Journeyman questions How the exam tests calculations
Exam format from the PSI candidate bulletin, read October 3, 2026.
How to size transformers fast
- Pick 1-phase or 3-phase (3φ uses line-to-line voltage, √3 factor).
- Choose inputs: kW + PF or V + I + PF.
- Set a headroom factor (1.25 is common; adjust for load type and expansion).
- Click “Calculate” to get load kVA, kVA with headroom, and a suggested rating.
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Notes & related tools with Transformer kVA calculator
- Final selection: consider temperature rise, ambient, ventilation, harmonics, and local codes.
- 1φ/3φ Power (kW/kVA/PF) converter
- Voltage drop calculator
