Wire Ampacity Calculator

This calculator uses a simplified thermal model. Results are approximations and may not match IEC/UL standards. Always verify with certified tables before real-world use.

What is Ampacity?

Ampacity is the maximum continuous current a conductor can carry without exceeding its temperature rating.

Calculation model

This calculator uses a simplified thermal balance between electrical losses and heat dissipation.

I_max = √( ΔT / ( R_elec · R_th ) )

Where:

ΔT = T_max − T_ambient
R_elec = electrical resistance per meter
R_th = total thermal resistance to air

This allows independent verification using basic heat transfer theory.

Cross-sectional area (A) — mm²

Conductor material

Insulation type

Ambient temperature (°C)

Maximum insulation temperature (°C) — editable

Insulation thickness (mm) — editable Laying / environment

Convection coefficient h (W/m²K)

Typical h: free horizontal cable ~6–12, forced/ventilated higher.

No calculation yet.

Values are per-meter; cable length cancels out.
Model is approximate and does not replace certified ampacity tables.
For multi-core, buried, conduit, or grouped cables, correction factors are required.