Overview
Whether sizing a generator, calculating cable size, or understanding electricity costs, the power triangle P=VI is the foundation.
The Formula
P=VĆI | I=PĆ·V | V=PĆ·I | Power in watts
Standard formula used by professionals worldwide
Worked Example
Step-by-step
Home backup: AC 1500W + Fridge 200W + Lights 200W + TV 100W = 2000W ā buy 2500W generator
Key Concepts
- Accuracy: Results are as accurate as the inputs you provide
- Units: Always use consistent units throughout your calculation
- Verification: Double-check important calculations before making decisions
- Professional advice: For major financial, health, or structural decisions, consult a qualified professional
Privacy and Security
- All calculations run entirely in your browser
- No data is sent to any server
- No sign-up or personal information required
- Your data stays private ā always
Frequently Asked Questions
kW vs kWh?
kW is rate of power. kWh is energy used over time. Bills charge kWh.
Why lights flicker on motor startup?
Surge current (5-7Ć running current) causes momentary voltage drop that dims lights.
What is power factor?
Ratio of real to apparent power. Inductive loads (motors) have PF < 1, requiring larger cables.