Last updated: October 2026

To test a capacitor with a multimeter, remove power, discharge the capacitor through a resistor, take it out of the circuit, then measure it in capacitance mode and compare the reading to the value printed on the part. If your meter has no capacitance mode, a resistance check can still reveal a shorted or very leaky capacitor. Neither test measures ESR, which is the most common way electrolytic capacitors fail, so a meter that reads “correct” does not prove a capacitor is good.

Safety scope: this guide covers capacitors from low-voltage bench circuits: breadboards, hobby boards and battery-powered projects. Capacitors inside mains-powered equipment (power supply primaries, microwave ovens, old TVs) can hold a dangerous charge after unplugging. Leave those to qualified technicians and the equipment maker’s service manual.

How a multimeter measures capacitance

Fluke explains that a multimeter determines capacitance by charging the capacitor with a known current, measuring the resulting voltage, and calculating the capacitance from that. Wikipedia’s article on capacitance meters adds that the slower the voltage rises, the larger the capacitance, and that typical digital meters cover roughly nanofarads to a few hundred microfarads, with some models going further. Check your meter’s manual for its exact capacitance range.

Step 1: Remove power and confirm it is off

Fluke’s procedure starts with three things before you touch the capacitor:

  1. Turn all power off.
  2. Use your multimeter to confirm the power is off. Set the meter to DC voltage for a battery or DC bench circuit.
  3. Discharge the capacitor.

On a breadboard, that means unplugging the battery or bench supply, then measuring across the power rails to confirm they read close to 0 V.

Step 2: Discharge the capacitor through a resistor

Fluke’s method is to connect a resistor across the capacitor terminals: it specifies a 20,000 Ω, 5 W resistor for five seconds, then using the meter to confirm the capacitor has fully discharged. Measure DC voltage across the capacitor’s leads afterward; it should read close to 0 V.

Discharging matters for two reasons. It protects you from any stored charge, and it protects your meter. Wikipedia’s ESR meter article notes that an ESR meter can be damaged if it is connected to a charged capacitor, and Fluke’s resistance guide also tells you to discharge capacitors before taking resistance readings.

Step 3: Remove the capacitor from the circuit

Fluke recommends detaching the capacitor from the circuit before measuring, because other components in parallel cause measurement errors. For through-hole parts, desolder at least one lead. For a breadboard, just pull the capacitor out.

While it is out, look at it. Fluke lists physical deterioration among the signs of a failing capacitor. A bulging top or leaking electrolyte on an electrolytic capacitor is a reason to replace it without further testing.

Step 4: Measure in capacitance mode

  1. Turn the dial to capacitance (the F symbol, or a function button on a shared position, per Fluke).
  2. Black lead in COM, red lead in the V/Ω jack, which Fluke’s jack guide lists as the input for capacitance.
  3. For electrolytic capacitors, connect red to the positive lead and black to the negative lead (the side marked with a stripe).
  4. Keep the leads connected for a few seconds. Fluke notes the meter needs this time to select the proper range automatically.
  5. Read the display.

For small values, Fluke recommends using REL (relative) mode to subtract the capacitance of the test leads. Press REL with the leads connected but nothing between them, then measure.

Step 5: Read the result

Compare the reading with the value printed on the capacitor. Capacitors are made to a tolerance, which is listed on the part’s datasheet, so judge the reading against that tolerance rather than expecting an exact match.

Fluke describes what the display can show:

  • A value close to the marked capacitance: the capacitance is within the meter’s range and the part is not open or shorted at the time of the test.
  • OL: either the capacitance is higher than the meter’s range, or the capacitor is faulty.

Fluke lists the common faults as short circuits, open circuits, and physical deterioration that changes the capacitance value.

Step 6: The resistance-mode check (for meters without capacitance)

If your meter has no capacitance range, a resistance test can still catch two faults. Wikipedia’s capacitance meter article puts it this way: a multimeter in a resistance range can detect a short-circuited capacitor (very low resistance) or one with very high leakage.

  1. Discharge the capacitor and remove it from the circuit (Steps 1 to 3).
  2. Set the meter to a high resistance range.
  3. Connect the leads, red to positive on electrolytics.
  4. Watch the reading.

What to look for:

  • Reading near 0 Ω that stays there: the capacitor is shorted.
  • Reading that starts low and climbs toward OL: the meter’s test current is charging the capacitor. The same article describes this on an analog meter as a needle that “kicks” to a low value and drifts back up to infinity. This gives only a crude sense that the capacitor holds charge.
  • Reading that settles at a moderate value instead of rising to OL: possible high leakage.

This test cannot tell you the capacitance value, and it does not measure ESR.

Step 7: Know what a multimeter cannot see (ESR)

ESR (equivalent series resistance) is the small internal resistance of a capacitor. According to Wikipedia’s ESR meter article:

  • A standard DC multimeter cannot measure ESR, because a steady direct current cannot pass through a capacitor.
  • ESR meters use AC or pulsed test signals at frequencies where the capacitor’s reactance is negligible, so what remains is the resistive part.
  • Excessive ESR is a far more common identifiable problem in aluminium electrolytics than out-of-tolerance capacitance. In other words, an aging electrolytic can show its marked capacitance on your meter and still fail in a circuit.
  • Many ESR meters can test in-circuit, because they use a test voltage too low to switch on semiconductor junctions.
  • An ESR meter can be damaged if connected to a charged capacitor, so discharge first.

So the practical rule is:

QuestionMultimeter capacitance modeMultimeter resistance modeESR meter
Can it flag a short?Can indicate a faultYes (reads near 0 Ω)Yes
Can it flag high leakage?NoCrudelyNo
Is the capacitance near the marked value?Yes, within the meter’s rangeNoDepends on model
Is the ESR too high?NoNoYes
Can it test in-circuit?Fluke says remove the partRemove the partOften designed to

If you repair power supplies, audio gear or retro electronics with many electrolytics, an ESR meter is worth adding to your bench. For general breadboard work, the multimeter tests above catch the obvious failures.

Common mistakes

  • Testing in-circuit. Parallel parts skew both capacitance and resistance readings. Lift a lead.
  • Skipping REL on small values. Lead capacitance adds to small readings, which is why Fluke recommends relative mode.
  • Reading too quickly. Fluke advises keeping the leads connected for a few seconds so the meter can settle on a range.
  • Trusting a good capacitance reading on an old electrolytic. Check ESR if the circuit still misbehaves.

For the basics of each meter mode, see how to use a multimeter. For choosing a meter with a capacitance range, see the electronics multimeter guide and the multimeter spec table.

FAQ

Why does my meter show OL in capacitance mode? Per Fluke, OL means either the capacitance is above the meter’s range or the capacitor is faulty. Check your meter’s maximum capacitance in the manual before assuming the part is bad.

Can I test a capacitor without removing it? Fluke recommends removing it, because other components cause measurement errors. ESR meters are the exception; many are designed to test in-circuit.

Does polarity matter when testing an electrolytic? Connect red to positive and black to negative to match the capacitor’s marking. This matches how the part is used in a circuit.

My capacitor measures fine but the circuit still fails. Why? A multimeter cannot measure ESR. Electrolytic capacitors commonly fail with high ESR while their capacitance still reads near normal, according to Wikipedia’s ESR meter article.

How do I discharge a small capacitor safely? Fluke’s method uses a resistor across the terminals, then a voltage check to confirm it reads close to 0 V.

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