Skin Effect Calculator
Calculate skin depth in copper, aluminum, and silver conductors at any frequency.
Component Values
Results
δ = skin depth (current zone)
Skin Depth Reference Table
| Frequency | Skin depth (Copper) | Skin depth (Aluminum) |
|---|---|---|
| 50 Hz | 9.335 mm | 11.95 mm |
| 1 kHz | 2.087 mm | 2.673 mm |
| 10 kHz | 660.1 µm | 845.2 µm |
| 1 MHz | 66.01 µm | 84.52 µm |
| 10 MHz | 20.87 µm | 26.73 µm |
| 1 GHz | 2.087 µm | 2.673 µm |
The skin effect is the concentration of AC current near the surface of a conductor. At DC, current distributes uniformly across the cross-section. As frequency increases, electromagnetic induction pushes current toward the surface. The depth at which current density falls to 1/e (about 37%) of its surface value is called the skin depth δ.
Skin depth is δ = √(ρ / (π × f × μ₀)), where ρ is resistivity and μ₀ = 4π×10⁻⁷ H/m. For copper at 1 MHz, δ ≈ 66 µm. At 100 MHz, δ ≈ 6.6 µm. The effective resistance of the conductor increases with frequency because only the thin skin layer carries current.
Skin effect is critical in RF coil design, transformer winding optimization, and high-frequency PCB trace analysis. Litz wire (stranded with individually insulated strands) is used in high-frequency inductors to maximize the surface area and minimize effective resistance at the operating frequency.
Skin Depth Formula
δ = √(ρ / (π × f × μ₀))Key Points
- δ = √(ρ/(π×f×μ₀)) — skin depth decreases with frequency
- Copper at 50 Hz: δ ≈ 9.3 mm (not significant)
- Copper at 1 MHz: δ ≈ 66 µm (significant in thin conductors)
- Skin effect increases AC resistance vs DC resistance
- Litz wire reduces skin effect in HF inductors
Applications
- RF coil and inductor winding design
- High-frequency PCB trace sizing
- Transformer winding loss estimation
- Litz wire gauge selection