3-Phase Power Calculator
Calculate three-phase power from line voltage, current and power factor — real power (kW), apparent power (kVA), reactive power (kVAR) and phase voltage — or work backwards from kW to the line current a load draws. Balanced load, with optional motor efficiency.
Input
Voltage between any two phases, e.g. 400, 415, 480 or 208.
Between 0 and 1. Use 1 for purely resistive loads such as heaters.
Output
| Quantity | Value |
|---|---|
| No data yet | |
More ways to use this tool
REST API
curl -X POST https://api.iotools.cloud/v1/tool/three-phase-power-calculator \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"mode": "power",
"voltage": "400",
"current": "20",
"realPower": "10",
"powerFactor": "0.85"
}'Swap in your own key from your account. The tool's fields are the body — no wrapper.
Ask an AI agent
Use the IOTools `three-phase-power-calculator` tool (3-Phase Power Calculator) on this input:
YOUR_INPUT_HEREPaste this at any agent connected to the IOTools MCP server, then add your input.
Embed widget
<iframe
src="https://iotools.cloud/embed/three-phase-power-calculator/"
width="100%" height="520" frameborder="0" scrolling="no" loading="lazy"
title="3-Phase Power Calculator — iotools.cloud"
sandbox="allow-scripts allow-forms allow-same-origin allow-downloads allow-popups allow-popups-to-escape-sandbox"
allow="clipboard-write"
style="width:100%;border:1px solid #e5e7eb;border-radius:12px;overflow:hidden"></iframe>
<script src="https://iotools.cloud/embed.js" async></script>Drop this into your own page — free, no key required, just a link back.
| Cost per API/MCP call | From 5 credits |
|---|---|
| Need more credits? | View pricing |
Also available with
Guides
Work out the power in a balanced three-phase circuit from its line voltage, current and power factor — or go the other way and find the current a load will draw from its kW rating.
How to use it
- Choose Power from voltage & current or Current from power (kW) & voltage.
- Enter the line-to-line voltage (for example 400 V, 415 V, 480 V or 208 V) and the power factor.
- Enter the line current or the real power, depending on the mode.
- Read the results table: real power (kW), apparent power (kVA), reactive power (kVAR), line current and phase voltage. The steps panel shows each formula with your numbers.
Formulas
- Real power: P (kW) = √3 × V × I × PF ÷ 1000
- Apparent power: S (kVA) = √3 × V × I ÷ 1000 = P ÷ PF
- Reactive power: Q (kVAR) = √(S² − P²)
- Line current: I = P × 1000 ÷ (√3 × V × PF)
- Phase voltage (wye): V ÷ √3
Notes
- Assumes a balanced load, the same current in all three phases.
- V is the voltage between two phases, not phase-to-neutral.
- For motors, kW on the nameplate is usually shaft output. Divide by efficiency to get the electrical input power before using the current mode.
- Size cables and breakers with the applicable electrical code, not on this result alone.