THE NUMORIX GUIDE
How to use the Inductance Calculator
Last reviewed September 14, 2026
What this calculator does
For an ideal inductor, the voltage relation is L = V/(dI/dt).
Formula and method
For an ideal inductor, the voltage relation is L = V/(dI/dt). Physical stored energy would be E = 1/2 L I^2, but this engine instead calculates energy as 1/2 L(dI/dt)^2 and stores dI/dt in its result field named current.
Variables and inputs
Voltage V is in volts and dI/dt is in A/s. The default is 10 V and 5 A/s; the UI requires a positive rate of current change and returns inductance in henries plus the engine's energy field in joules.
Worked example
For V = 10 V and dI/dt = 5 A/s: L = 10/5 = 2 H. The current engine then reports 1/2(2)(5^2) = 25 J, but 25 is a rate-of-change value in A/s, not a current in A, so this energy is not a physical stored-energy result without an actual current input.
How to interpret the result
The inductance result is meaningful for the entered voltage and current slope: a larger L requires more voltage for the same dI/dt. The displayed energy should be treated as an implementation artifact until the engine accepts and uses a separate current value.
Common mistakes to avoid
Do not substitute current in amperes for dI/dt when finding L, and do not interpret A/s as A. For real stored energy, use the actual instantaneous current I in E = 1/2LI^2 rather than the value shown in this calculator's energy calculation.
Assumptions and limitations
The route assumes an ideal constant inductance and does not model resistance, saturation, core losses, switching transients, or AC impedance. Its energy calculation uses dI/dt as if it were current, and the UI provides no separate current input to correct that limitation.