Electrical Load & Wire Gauge Calculator
Add up appliance wattage to estimate total current draw, breaker size, and wire gauge.
Appliances
Quick add:
What is it?
This calculator adds up the wattage of your appliances to estimate total electrical current draw, then suggests a breaker size and wire gauge using common residential wiring rules of thumb.
Formula
Current (A) = Total Watts ÷ Voltage
Breaker Size ≥ Current × 1.25
Formula Explanation
Total load in watts is divided by the supply voltage to get the current draw in amps. A 25% safety margin is applied before matching to the next standard breaker size, which is standard electrical practice for continuous loads. Wire gauge is then matched to the calculated current using typical copper wire ampacity ratings.
Example Calculation
An air conditioner (1500W), refrigerator (200W), and geyser (2000W) on a 230V supply draw a total of 3700W ÷ 230V ≈ 16.1A, suggesting a 20A breaker and 4 mm² wire.
How to Use
- Select your supply voltage (110V or 230V).
- Add each appliance with its wattage and quantity, or use the quick-add buttons for common appliances.
- Review the total load, current draw, recommended breaker size, and wire gauge.
Benefits
- Combines multiple appliances into a single load calculation instead of doing the math by hand.
- Includes a standard 25% safety margin when recommending breaker size.
- Quick-add presets speed up estimating a typical household circuit.
Use Cases
- Sizing a new circuit before adding a high-wattage appliance like an AC or geyser.
- Checking whether an existing circuit breaker is adequately rated for the appliances on it.
- Rough planning before consulting an electrician for a home wiring or renovation project.
What Your Result Means
The recommended breaker and wire gauge are conservative estimates based on general residential wiring rules of thumb, not a formal electrical code calculation. They're a useful starting point for a conversation with a licensed electrician, not a substitute for one.
Tips
- Group appliances by circuit rather than calculating your whole house at once, since each circuit needs its own breaker and wire sizing.
- High-wattage appliances like ACs, geysers, and ovens should generally be on dedicated circuits.
- Always round up to the next standard wire and breaker size rather than down.
Common Mistakes
- Using this tool as a final electrical design instead of a rough planning estimate — always get final sizing verified by a licensed electrician.
- Forgetting to account for appliance quantity (e.g. multiple AC units) when totaling load.
- Ignoring that some appliances (like ACs and motors) draw a higher starting current than their running wattage suggests.
FAQs
Is this a substitute for an electrician's calculation?
No — this tool gives a rough estimate using common rules of thumb. Actual wire and breaker sizing must follow your local electrical code and be verified by a licensed electrician.
Why is there a 25% safety margin on the breaker size?
Continuous electrical loads are conventionally sized with a 25% margin above the calculated current to avoid nuisance tripping and reduce fire risk from sustained near-capacity loads.
Does wire gauge depend on more than just current?
Yes — wire length, ambient temperature, insulation type, and number of conductors bundled together all affect the correct wire gauge in a real installation, which this simplified tool does not account for.
What voltage should I select?
Use 230V for standard single-phase household circuits in most of Asia, Europe, Africa, and Australia, or 110V for regions like North America and Japan.
This tool provides rough planning estimates only. Always have electrical wiring designed, installed, and verified by a licensed electrician.
Last updated: July 26, 2026