Magnetic Field Wire
Enter current and distance to compute the magnetic flux density around a straight wire via B = μ₀I / 2πr.
Input Values
A
Amperes — direction does not affect field magnitude.
Perpendicular distance from the wire center.
Formula
B = μ₀ · I / (2π · r)
μ₀ = 4π × 10⁻⁷ T·m/A
Results
Enter current and distance, then click Calculate.
Tesla (T)
SI base unit
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Millitesla (mT)
10⁻³ T
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Microtesla (μT)
10⁻⁶ T — common for AC power lines
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Gauss (G)
CGS unit; 1 T = 10,000 G
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Summary
Enter current and distance to compute the magnetic flux density around a straight wire via B = μ₀I / 2πr.
How it works
- Enter the current (I) flowing through the wire in amperes.
- Enter the perpendicular distance (r) from the wire's center in meters or centimeters.
- The calculator applies B = μ₀I / 2πr, where μ₀ = 4π × 10⁻⁷ T·m/A.
- Results are displayed in Tesla, millitesla, and Gauss.
- Use the unit toggles to enter distance in meters or centimeters.
Use cases
- Physics homework involving Ampere's law problems.
- Estimating EMF exposure near high-current power cables.
- Engineering checks when routing PCB traces near current-carrying conductors.
- Lab prep for verifying measured magnetic fields with a Hall probe.
- Teaching demonstrations of the inverse-distance relationship of B.
Frequently Asked Questions
Last updated: 2026-06-11 ·
Reviewed by Nham Vu