Coil Inductance Calculator
Calculate coil inductance for series circuits. Enter circuit values to calculate the selected electrical quantity.
Series Inductors
Electronics guide · Circuit components and networks
About Series Inductance Calculator
Add up to four inductor values to estimate their total inductance when connected in series without significant magnetic coupling. The tool reports the series total in microhenries and displays the sum formula.
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.Enter the inductance values in microhenries for the components you are using.
- 2.Leave optional inductor fields blank when they are not part of the series string.
- 3.Calculate and compare the total with the intended circuit value; confirm the inductors are actually connected in series.
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, total inductance Ltotal = L1 + L2 + … + Ln. The current is common through the series path, and each inductance contributes its voltage response. Magnetic coupling can add mutual-inductance terms that this simple sum ignores.
Worked Example
Two uncoupled 10 µH and 15 µH inductors in series have an ideal total of 25 µH.
Where This Tool Can Help
Check a basic series combination or understand how adding inductors changes the nominal value.
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
The calculation does not include mutual coupling, winding resistance, core saturation, frequency-dependent losses, tolerance, or self-resonance. Nearby coils may couple magnetically, changing the result. Check datasheets and measure the assembled circuit where precision matters.
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 series inductance always add?
It adds for ideal uncoupled inductors; magnetic coupling can alter the total.
Can I enter values in different units?
Convert all values to the same unit first; the fields are labeled µH.
Does this calculate parallel inductors?
No. It reports a series sum only.
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.