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What is the Inductance of a Solenoid (Coiled Wire)?

July 24, 2023

The inductance of a solenoid is approximately:

Where r is the radius in inches, l is the length in inches, and n is the number of turns.

It may also be calculated more precisely from this equation (from Ampere’s Law) with similar results:

Where μ is free space permeability 4π*10-7 H/m
n is the number of turns
A is the cross-sectional area in m2
l is the length of the coil in meters

See this and more important radio frequency charts and formulas in this comprehensive application note