Enter your First Inductor (L1) and Second Inductor (L2) values with their units, plus the Coupling Coefficient (K), and this Mutual Inductance Calculator gives you the Mutual Inductance (M) in both henries (H) and microhenries (µH), along with a Coupling Strength rating to show how tightly your two inductors are linked.
Mutual Inductance (M)
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Mutual Inductance (H)
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Mutual Inductance (µH)
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Coupling Strength
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Mutual inductance (M) is the ability of one inductor to induce voltage in another nearby inductor. It's calculated using the formula M = K × √(L1 × L2), where K is the coupling coefficient, L1 and L2 are the individual inductance values.
The coupling coefficient K represents how much magnetic flux from one inductor links with the other inductor. K ranges from 0 (no coupling) to 1 (perfect coupling). Typical values are 0.1-0.9 for air-core transformers and 0.95-0.99 for iron-core transformers.
As the distance between inductors increases, the coupling coefficient K decreases, which reduces mutual inductance. Closer inductors have stronger magnetic field coupling and higher mutual inductance values.
Mutual inductance calculations are essential for designing transformers, coupled inductors in switching power supplies, wireless power transfer systems, and RF circuits where electromagnetic coupling between coils is important.
Coupling strength is categorized as: Weak (K < 0.3), Moderate (K = 0.3-0.7), Strong (K = 0.7-0.9), and Very Strong (K > 0.9). Higher coupling means more efficient energy transfer between inductors.
Yes, mutual inductance can be negative depending on the relative winding directions of the inductors. If the magnetic fields oppose each other, the mutual inductance is negative, but the magnitude calculation remains the same.
Mutual inductance uses the same units as self-inductance: henries (H), millihenries (mH), microhenries (µH), nanohenries (nH), and picohenries (pH). The choice depends on the application and inductance magnitude.