Calculate Total Inductance for Series and Parallel Networks
Connection Type
Number of Inductors
L1 (H)
L2 (H)
Result
Step-by-Step Calculation
Inductance Formulas
Series: Lt = L1 + L2 + ... + Ln
Parallel: 1/Lt = 1/L1 + 1/L2 + ... + 1/Ln
Series aiding (coupled): Lt = L1+L2+2M
Series opposing: Lt = L1+L2-2M
Inductors follow the same rules as resistors for series and parallel combinations. Series adds inductance, parallel reduces it. Note: when inductors are close together, mutual inductance can significantly alter the total value. Our calculator assumes no magnetic coupling.
⚠Coupled inductors (transformers) have mutual inductance M = k√(L1×L2) where k is the coupling coefficient (0 to 1). Tight coupling (k≈1) affects total significantly.
Series vs Parallel Inductance
Inductors in series combine like resistors (additive). Inductors in parallel also combine like resistors (reciprocal). Unlike capacitors, inductors have the same rules as resistors. This is because the voltage-current relationship for inductors involves integration, while capacitors involve differentiation.
Series Inductors
Lt = L1 + L2 + ... Same current through all. Mutual inductance can aid or oppose. Higher total inductance.
Parallel Inductors
1/Lt = 1/L1 + 1/L2 + ... Same voltage across all. Mutual inductance creates current sharing between paths.
Mutual Coupling
M = k√(L1×L2). Dot convention determines series aiding (+) or opposing (-). Transformers use mutual inductance for energy transfer.
Comparison
Inductors: same rules as resistors (series adds, parallel subtracts). Capacitors: opposite (series subtracts, parallel adds).
Teaching Example: L1=10mH, L2=22mH in series vs parallel.
Series: Lt = 10 + 22 = 32mH (greater than each).
Parallel: 1/Lt = 1/10+1/22 = 0.1+0.04545 = 0.14545 → Lt = 6.875mH (less than each).
Same as resistor behavior.
Applications
Power FiltersRF TuningEMI SuppressionTransformersDC-DC Converters
Frequently Asked Questions
Series vs parallel inductance?▼
Series: Lt = L1+L2 (adds). Parallel: 1/Lt = 1/L1+1/L2 (subtracts). Same behavior as resistors, opposite to capacitors.
How to increase inductance?▼
Connect in series: Lt = L1+L2. More turns on the core. Use higher permeability core material (ferrite instead of air).
Does mutual inductance matter?▼
Yes. Close inductors share magnetic flux. Series aiding: +2M. Series opposing: -2M. k=1 gives 4× for aiding. Shield inductors to minimize unwanted coupling.
Inductors vs capacitors rules?▼
Same as resistors: series adds, parallel reciprocals. Capacitors are opposite: series reciprocals, parallel adds. Due to V=L dI/dt vs I=C dV/dt.
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