Parallel Inductors Calculator — Equivalent Inductance
Find the total (equivalent) inductance when inductors are wired in parallel. Enter up to four inductor values and their unit — the calculator applies the reciprocal-sum formula and shows the result alongside each individual value.
Number of inductors
Unit
mH
mH
mH
Equivalent inductance of all inductors connected in parallel (no mutual coupling assumed)
- 1
Sum of reciprocals 1/L₁ + 1/L₂ + …
1 ÷ 10 + 1 ÷ 20 + 1 ÷ 30 = 0.183333Parallel inductors add their reciprocals, just like parallel resistors. - 2
Total inductance = 1 ÷ (sum of reciprocals)
1 ÷ 0.183333 = 5.4545
How does this calculator work?
Parallel inductors combine by the reciprocal-sum rule: 1/L_total = 1/L₁ + 1/L₂ + … The result is always smaller than the smallest individual inductor. For two inductors, L_total = L₁L₂/(L₁+L₂). This assumes no mutual magnetic coupling between coils. Enter 2–4 inductor values to get the equivalent inductance instantly.
Formula
How this is calculated
When inductors are connected in parallel (assuming no magnetic coupling between them), they share the same voltage but the total current divides among them. Applying Kirchhoff's voltage law and the inductor voltage–current relationship V = L dI/dt shows that the reciprocals add: 1/L_total = 1/L₁ + 1/L₂ + … + 1/Lₙ. This is mathematically identical to resistors in parallel.
For two inductors the formula simplifies to the product-over-sum shortcut: L = L₁ × L₂ / (L₁ + L₂). The key practical consequence is that the parallel equivalent is always smaller than the smallest individual inductor — unlike series connection where inductances simply add. This is used in power-supply design when a single small inductor value is not available but smaller ones can be combined in parallel.
This calculator assumes no mutual inductance between the coils. If coils are physically close and share a magnetic flux path (mutual inductance M), the formula becomes more complex and depends on whether they are aiding or opposing. For well-separated, uncoupled inductors the formula here is exact.
Frequently asked questions
In parallel, the combined path presents less opposition to current change (less inductance) because multiple paths share the total current. Mathematically, 1/L_total > 1/L_smallest, so L_total < L_smallest — the same reason parallel resistors give a smaller resistance than the smallest resistor.
The formula is identical: both use the reciprocal sum. However, inductors store energy in a magnetic field and their impedance grows with frequency (X_L = 2πfL), while resistors dissipate energy with frequency-independent impedance. In AC circuits the reactances combine by the same formula, but the analysis also includes the inductor's phase relationship with voltage and current.
If two inductors share flux (as in a transformer or tightly wound pair), a mutual inductance M exists. For aiding coupling the parallel equivalent is (L₁L₂ − M²) / (L₁ + L₂ − 2M); for opposing coupling it is (L₁L₂ − M²) / (L₁ + L₂ + 2M). This calculator assumes M = 0 (no coupling) — physically separate, shielded inductors on a PCB typically satisfy this assumption well.
Also known as
TG we-Calculate Editorial Team. (2026). Parallel Inductors Calculator — Equivalent Inductance [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/parallel-inductors-calculator
TG we-Calculate Editorial Team. "Parallel Inductors Calculator — Equivalent Inductance." TG we-Calculate. 2026. https://we-calculate.com/calculator/parallel-inductors-calculator.
TG we-Calculate Editorial Team, "Parallel Inductors Calculator — Equivalent Inductance," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/parallel-inductors-calculator
@misc{wecalculate_parallel_inductors_calculator, title = {Parallel Inductors Calculator — Equivalent Inductance}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/parallel-inductors-calculator}}, year = {2026}, note = {TG we-Calculate} }
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