How to choose an LCR meter for R, L and C testing
An LCR meter measures inductance, capacitance and resistance along with the loss factor. This guide shows how to pick the right test frequency, basic accuracy and test level, and why Kelvin sensing and the correct equivalent circuit decide whether your readings can be trusted.
View LCR metersWhat does an LCR meter measure and how?
An LCR meter applies a sinusoidal AC voltage at a defined frequency to the component and evaluates the resulting current and phase angle. From this it calculates the complex impedance Z and separates it into the target values inductance L, capacitance C and resistance R, plus the dissipation factor D or quality factor Q.
Because many components are frequency dependent, a measured value is only valid at the selected test frequency. An electrolytic capacitor shows a different capacitance at 120 Hz than at 100 kHz, and an inductor a different inductance near its self-resonance.
- R - ohmic resistance, largely independent of frequency.
- L - inductance of coils, chokes and transformers.
- C - capacitance of film, ceramic and electrolytic capacitors.
- D and Q - dissipation factor and quality factor as quality indicators.
- ESR - equivalent series resistance, key for electrolytics and smoothing capacitors.
Which criteria matter when choosing an LCR meter?
The three decisive criteria are test frequency, basic accuracy and test level. The test frequency should be as close as possible to the component's later operating frequency so the reading is relevant in practice.
Remember that the quoted basic accuracy only applies within a defined impedance and frequency window. At the range limits, for example very small resistances or very small capacitances, the measurement uncertainty rises significantly.
Why regular calibration keeps your readings defensible and reproducible.
Read the guideHow to measure correctly and avoid errors?
The biggest error sources are lead resistance, stray capacitance and a missing zero calibration. With small resistances and inductances the lead resistance dominates whenever only two leads are used.
- Perform open and short compensation before every measurement series.
- Use a 4-terminal Kelvin connection as soon as values below 100 ohm or below 1 microhenry are measured.
- Fully discharge any capacitor before connecting it.
- Choose the matching equivalent circuit: series model for low impedances, parallel model for high ones.
- Keep the leads short and do not move them during the measurement.
For documented testing, traceable calibration to ISO/IEC 17025 is worthwhile. It ensures the manufacturer's stated basic accuracy is maintained over time and that readings stay reproducible.
Frequently asked questions
Which test frequency do I need for electrolytic capacitors?
Electrolytics are usually tested at 100 or 120 Hz for capacitance and at 100 kHz for ESR. Choose a meter that offers both frequencies.
What is the purpose of zero calibration?
Open and short compensation removes the errors of leads and test fixtures. Without it, small values are significantly distorted.
Series or parallel equivalent circuit?
Use the series model for low impedances (large C, small R) and the parallel model for high impedances (small C, large R). The wrong model gives apparently wrong values.
Why is an adjustable test level important?
Class 2 ceramic capacitors change their capacitance with the signal voltage. Only an application-matched test level gives realistic values.
Looking for the right LCR meter?
We stock LCR meters from handy service tools to precision instruments with adjustable frequency, test level and 4-terminal Kelvin connection - with a calibration certificate on request.
High accuracy
Instruments with basic accuracy from 0.05 % in the range.
Calibratable
Traceable calibration to ISO/IEC 17025 available.
Flexible frequency
From 100 Hz to 1 MHz for every component class.
Expert advice
Measurement specialists help you choose.