How to Test a Capacitor With a Multimeter (Step-by-Step Guide)
If a circuit isn't working the way it should, a faulty capacitor is one of the most common culprits — and the good news is you don't need expensive equipment to check one. A basic digital or analog multimeter is enough to tell you whether a capacitor is good, weak, or completely dead.
This guide walks you through testing a capacitor safely, whether your multimeter has a dedicated capacitance setting or not.
Why Capacitors Fail
Capacitors store and release electrical energy, and over time — especially with heat, age, or incorrect voltage — they can fail in a few common ways:
Drying out, which reduces their capacitance value
Short-circuiting internally
Going completely open (no longer holding or releasing charge)
A failed capacitor is a frequent cause of problems in power supplies, audio equipment, fans, and other circuits.
Safety First: Always Discharge the Capacitor
Before testing any capacitor, disconnect it from power and discharge it. Capacitors — especially larger ones used in power supplies — can hold a dangerous electrical charge even after the power is switched off.
To discharge safely:
Connect a resistor (around 1kΩ–10kΩ) across the two terminals for a few seconds, or
For small, low-voltage capacitors only, briefly touch the leads together with an insulated tool
Never test a capacitor that's still connected to a live circuit.
What You'll Need
A digital multimeter (with or without a dedicated capacitance/μF setting), or an analog multimeter
The capacitor removed from the circuit, or at least one leg desoldered, for an accurate reading
Step 1: Visual Inspection
Before you even pick up the multimeter, look at the capacitor itself:
A bulging or domed top is a clear sign of failure
Leaking residue (a brown or white substance) around the base
Burn marks or a melted casing
If you see any of these signs, the capacitor has already failed — no further testing needed.
Step 2: Testing With a Multimeter That Has a Capacitance (μF) Setting
Most modern digital multimeters, including affordable ones, include a capacitance mode (look for the F or μF symbol on the dial).
Discharge the capacitor (see above)
Remove it from the circuit, or desolder at least one leg
Set the multimeter dial to the capacitance setting
Touch the probes to the capacitor's two leads
Read the value on the display and compare it to the rating printed on the capacitor body
A healthy capacitor will read close to its printed rating — usually within about 20%. A reading far below that, or a reading of zero, means the capacitor is weak or dead.
Step 3: Testing With a Multimeter That Has No Capacitance Setting
If you're using a basic analog multimeter, or a digital one without a capacitance mode, you can still get a useful good/bad result using the resistance (Ω) setting:
Discharge the capacitor
Set the multimeter to a high resistance (Ω) range
Touch the probes to the two leads and watch the display, or the needle on an analog meter
Here's how to read the result:
Good capacitor: Resistance starts low, then climbs steadily toward infinity as the capacitor charges from the multimeter's small test current
Shorted (bad) capacitor: Resistance stays at or near zero and never rises
Open (bad) capacitor: Resistance shows infinity (or OL) immediately, with no change at all
This method won't give you an exact capacitance value, but it will reliably tell you whether a capacitor is good or has failed.
Quick Reference
ResultWhat It MeansReading close to printed value (capacitance mode)Capacitor is healthyReading far lower than printed value, or zeroCapacitor is weak or deadResistance rises steadily toward infinityCapacitor is goodResistance stays near zeroCapacitor is shortedResistance is infinite immediately, no changeCapacitor is open/dead
Frequently Asked Questions
Can I test a capacitor without removing it from the circuit?
It's not recommended. Other components connected to the capacitor can affect the reading and give you a false result. For an accurate test, desolder at least one leg, or remove the capacitor entirely.
My multimeter shows "OL" when testing — what does that mean?
In capacitance mode, OL usually means the value is outside the meter's measurable range, or the capacitor is open. In resistance mode, seeing the reading climb to OL over a few seconds is actually a normal sign of a healthy capacitor charging up.
Is it dangerous to test a capacitor?
It can be, if you skip the discharge step. Capacitors in power supplies and audio equipment can hold a charge well after the power is off. Always discharge a capacitor safely before testing or handling it.
Need a Replacement?
If your testing shows a capacitor has failed, HS Electronics stocks a range of electrolytic capacitors and digital and analog multimeters if you need to upgrade your testing tools. Visit our store on Hall Road, Lahore, or shop online at hselectronics.pro.
