Diode Ideality Factor Calculator

Estimate diode quality using slope of exponential conduction. Include thermal voltage, units, and data checks. Make better device models with verified ideality factors today.

Calculator Inputs

Method

Two-point (V1, I1) and (V2, I2) Multi-point fit from a V–I dataset

Use a forward-bias region with exponential behavior.

Temperature (K)

Room temperature is often about 300 K.

Voltage unit

Current unit

Example Data Table

Temperature (K)	V1 (V)	I1 (mA)	V2 (V)	I2 (mA)	Estimated n
300	0.55	0.50	0.65	5.00	≈ 1.68

This example uses a 10× current increase over a 0.10 V rise.

Formula Used

Diode equation (forward bias)

I ≈ Is · exp( V / (n · Vt) )

Where Is is saturation current, n is ideality factor.

Thermal voltage

Vt = kT / q

k is Boltzmann constant, q is elementary charge.

Two-point ideality factor

n = (V2 − V1) / ( Vt · ln(I2 / I1) )

Multi-point fit

ln(I) = ln(Is) + V / (n · Vt)

The slope of ln(I) versus V equals 1/(n·Vt).

How to Use This Calculator

Choose a measurement region with exponential forward conduction.
Set temperature and select your voltage and current units.
Pick two points, or paste a dataset for fitting.
Press Calculate to view n, Vt, and Is.
Download CSV or PDF to save your results.

Practical Notes

Series resistance can inflate n at higher currents.
Recombination effects can raise n near low currents.
Use consistent temperature and stable measurement equipment.
For best fitting, keep points within one bias regime.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.