🌀 Skin Depth Calculator
Find the skin depth of a conductor at a given AC frequency, the depth below the surface where current density falls to about 37% of its surface value.
What is skin depth?
At high frequencies, alternating current tends to flow near the outer surface of a conductor rather than through its full cross-section, a phenomenon called the skin effect. Skin depth (δ) is the distance below the surface at which current density has dropped to about 1/e (roughly 37%) of its value at the surface, and it shrinks as frequency, conductivity, or permeability increases.
How this calculator works
The calculator uses the standard formula δ = √(ρ / (π·f·μ₀·μr)), where ρ is the material’s resistivity, f is the AC frequency, μ₀ is the permeability of free space, and μr is the material’s relative permeability (1 for non-magnetic metals like copper or aluminum, higher for ferromagnetic materials like steel). A smaller skin depth means current is more concentrated near the surface, which increases effective AC resistance compared to DC resistance.
This tool is for general educational and design-estimation purposes. For critical RF, power, or conductor-sizing decisions, verify results with detailed engineering calculations.