Series and Parallel Inductance
Calculate total inductance for series and parallel circuits. Enter circuit values to calculate the selected electrical quantity.
Inductor Values (mH)
Electronics guide · Circuit components and networks
About Series and Parallel Inductance Calculator
Estimate an equivalent inductance for components in series or parallel. The basic relationships assume uncoupled, ideal inductors; coils with mutual magnetic coupling can behave differently.
Component calculations simplify a circuit into a formula or ideal model. Real parts have tolerances, ratings, parasitic effects, and wiring details that can change how a circuit behaves, so use the result as a design estimate and compare it with the component datasheet and circuit conditions.
How to Use This Tool
- 1.Choose series or parallel and enter the inductance values with consistent units.
- 2.Confirm the inductors are treated as uncoupled and the chosen arrangement matches the schematic.
- 3.Calculate the equivalent inductance, then check current, saturation, resistance, and frequency limits in the component datasheets.
Technical Details to Check
1.Match values to the right circuit position
Resistors, capacitors, inductors, and semiconductor pins are not interchangeable inputs. Follow the labels or diagram and check that each value belongs to the correct component or branch.
2.Ideal formulas have assumptions
A calculator may assume a balanced bridge, an ideal switch, a simple RC or RL network, or a specific transistor operating mode. Confirm that the real circuit matches that model before using the result.
3.Datasheet ratings still matter
Calculated values do not establish a safe operating point. Check voltage, current, power, temperature, frequency, and tolerance ratings for every part that will be used.
4.Small errors can move the result
Component tolerances and measurement uncertainty can change timing, bias, resonance, or dissipation. For a design with tight limits, calculate a range using realistic minimum and maximum values.
How the Calculation Works
For ideal uncoupled inductors in series, Ltotal is the sum of the inductances. In parallel, 1/Ltotal is the sum of 1/Li; for two inductors, Ltotal = L1L2/(L1+L2). Mutual coupling adds terms that this simple calculator does not include.
Worked Example
Two 10 mH uncoupled inductors in series give 20 mH; in parallel they give 5 mH.
Where This Tool Can Help
Check ideal equivalent values while planning a circuit or learning how connection changes inductance.
Checking a first design estimate
Use the formula result to choose a likely component range, then test the circuit with real part values and operating conditions.
Learning how a circuit behaves
Change one input at a time and observe the result to see how a resistor, capacitor, inductor, or device parameter affects the calculation.
Comparing candidate components
Compare values on the same unit basis, then check package, tolerance, power rating, voltage rating, and availability in the relevant datasheet.
Reviewing a schematic
Use the result as a cross-check for a hand calculation, simulation, or design note while keeping the assumed topology clear.
Tips for More Reliable Results
- Use consistent units and copy component values carefully, including prefixes such as m, µ, n, and k.
- Check polarity, pin names, and series or parallel placement against the circuit diagram.
- Use worst-case component tolerances when a timing or operating range must stay within limits.
- Verify the result against datasheets and an appropriate bench measurement before building a safety-critical circuit.
Limitations and Assumptions
Core saturation, winding resistance, frequency, tolerance, and magnetic coupling can change behavior. The output is not a current or safety rating. Follow datasheet limits and analyze coupled coils separately.
The calculator can only model the values, topology, and operating assumptions represented by its inputs. It does not inspect a physical circuit, validate wiring, or confirm a part is safe for its electrical and thermal conditions. Use design documentation and datasheets for final component choices.
Frequently Asked Questions
Does the series formula assume ideal parts?
Yes, it ignores losses and mutual coupling.
What happens to two equal inductors in parallel?
The ideal equivalent is half the inductance of one.
Can coupled coils use this result?
Not reliably; mutual inductance must be included.
Will the result exactly match a real circuit?
Not always. The formula may use ideal components and may not include tolerances, parasitic effects, loading, or temperature changes.
Can I select a component from the calculated value alone?
No. Also check ratings, tolerance, package, polarity, availability, and the circuit's operating conditions.