Calculation method and supported range
δ = √[1/(πf μ₀ μr σ)]. μ₀ ≈ 1.25663706212 × 10⁻⁶ H/m. The input conductivity is megasiemens per metre, not siemens per metre.
Good-conductor, local continuum approximation (σ ≫ ωε), homogeneous material, real constant μr. Not valid for arbitrary dispersive magnetic materials, superconductors or very thin-film/anomalous skin effects. Skin depth alone is not insertion loss.
Technical sources
Using the result
Skin depth describes electromagnetic penetration, not the complete resistance of a patterned trace. Copper roughness, plated finishes and the actual current distribution can change conductor loss. The default copper conductivity is an illustrative bulk value and is not a guarantee for plated PCB copper.
From a calculation to a released design
Keep the input assumptions with the result. Recalculate when the ordered material, dielectric height, copper or operating conditions change. Confirm the final construction with the fabricator and use field simulation or measurement wherever the simplified model omits an important effect.
See the controlled-impedance guide and material selection workflow for the next checks.