Wire Skin Effect Calculator
At high frequencies, current stops flowing through the full cross-section of a conductor and concentrates near the surface. Enter a frequency and material to calculate skin depth.
Enter a frequency to calculate skin depth.
Based on standard resistivity values (copper: 1.68×10⁻⁸ Ω·m, aluminum: 2.82×10⁻⁸ Ω·m at 20°C). For general engineering reference only. Assumes non-magnetic conductor — verify against manufacturer specifications for safety-critical or high-power applications.
What Is Skin Effect?
Skin effect is the tendency of alternating current to flow near the outer surface of a conductor rather than through its full cross-section. As frequency increases, current is increasingly confined to a thin outer layer — the "skin depth" (δ). The center of the conductor carries little to no current at high enough frequencies, making the extra copper electrically useless.
The Formula
Skin depth is calculated using:
δ = √( ρ / (π × f × μ) )
where δ is skin depth in meters, ρ is the electrical resistivity of the conductor (Ω·m), f is frequency in Hz, and μ is magnetic permeability (H/m) — for copper and aluminum this equals μ₀ (4π × 10⁻⁷ H/m).
Practical Reference Values (Copper)
| Frequency | Skin Depth | Typical Context |
|---|---|---|
| 60 Hz | 8.5 mm | Mains power — negligible effect on typical wire |
| 10 kHz | 0.66 mm | Switching power supplies — starts to matter for thick wire |
| 1 MHz | 0.066 mm (66 μm) | RF circuits, high-speed signals — significant |
| 100 MHz | 6.6 μm | PCB traces, RF connectors — severe |
| 1 GHz | 2.1 μm | Microwave — only surface plating carries current |
Design Implications
When skin depth is much smaller than your conductor radius, effective AC resistance increases significantly compared to DC resistance. For a deeper look at how skin effect interacts with connector plating and high-frequency signal loss, see Skin Effect & AC Loss: Why High-Frequency Signals Hug the Surface.