Current Density Calculator Formula
Understand the math behind the current density calculator. Each variable explained with a worked example.
Formulas Used
Current Density
current_density = current / (area * 1e-6)Current Density
current_density_amm2 = current / areaVariables
| Variable | Description | Default |
|---|---|---|
current | Current(A) | 10 |
area | Cross-Sectional Area(mm²) | 2.5 |
How It Works
Current Density
Current density describes how much current flows through a unit area of a conductor.
Formula
J = I / A
where I is the current and A is the cross-sectional area of the conductor. High current density causes excessive heating.
Worked Example
10 A through a wire with 2.5 mm² cross-section.
- 01J = I / A
- 02J = 10 / 2.5 mm²
- 03J = 4 A/mm²
- 04J = 4,000,000 A/m²
Frequently Asked Questions
What is a safe current density for copper wire?
For continuous operation, copper wire should typically not exceed about 4 to 6 A/mm². Higher densities cause excessive heating.
Why does current density matter?
Current density determines resistive heating in the conductor. Exceeding safe limits can melt insulation or cause fires.
Is current density uniform across a wire?
At DC, yes. At high AC frequencies, the skin effect causes current to concentrate near the wire surface, increasing effective current density.
Ready to run the numbers?
Open Current Density Calculator