Best ESR Tester for Capacitors: 6 Picks for Bench Repair
As an Amazon Associate we earn from qualifying purchases. Details
An ESR tester helps you find bad electrolytic capacitors that still read normal capacitance but run hot, ripple or fail under load. ESR means equivalent series resistance, and it rises as an electrolytic dries out. This guide compares a dedicated in-circuit ESR meter, a capacitance and ESR meter, and wider LCR or component testers that also show ESR, so you can match the tool to board repair, bench sorting or hobby use.
These are bench tools, not mains installation meters. Power off the circuit and discharge capacitors before every test. Work on mains circuits can kill, the meter’s CAT rating must suit the circuit, and panel or service work belongs to a licensed electrician. Most listings here do not state a CAT rating, so do not treat any of them as safe for household mains.
Quick answer
For repair work on powered-off boards, the GME in-circuit ESR tester is the clearest fit: it states a 100 kHz test signal at 15 mVp-p and testing in or out of circuit from 0.47µF to 2200µF. For sorting loose parts and checking more than ESR, the FNIRSI LC1020E is an LCR meter with five test frequencies and ESR as a secondary reading. The Velleman Atlas ESR70 gives a capacitance and ESR reading with a stated 0.00 to 40.0 ohm span. The Signstek is a quick low-ohm and ESR checker with a printed ESR table.
The FORIOT and diymore units are general component testers. The listings here do not give an ESR range for either, so treat them as hobby tools and check the listing before relying on them for low-ESR decisions.
Comparison table
| Tester | Type stated | Capacitor span stated | ESR info stated | Test signal stated | Probes or fixture | Size or weight |
|---|---|---|---|---|---|---|
| FNIRSI LC1020E | LCR meter | 1pF to 100mF | ESR as a secondary parameter; no ohm span | 100Hz, 120Hz, 1kHz, 10kHz, 100kHz; 0.1/0.3/0.6V | 3-pin sockets and 5-slot jacks | 250 g; 3.35 x 1.38 x 7.28 inches |
| Signstek MESR-100 V2 | ESR and low-ohm meter | Not stated | 0.01R-100R in title; printed ESR table | Auto-ranging; no frequency stated | Dual terminals; upgraded test clip | 8 ounces |
| GME in-circuit ESR tester | In-circuit ESR and capacitance meter | 0.47µF to 2200µF | No ohm span stated | 100 kHz; 15 mVp-p | One-handed tweezers, gold plated tips | 16 ounces; 6 x 3.5 x 2 inches |
| Velleman Atlas ESR70 | Capacitance and ESR meter | 1uF to 22000uF | 0.00 to 40.0 ohms; 0.01 ohm resolution | Not stated | Not stated | 0.1 kg; 5.51 x 7.87 x 1.18 inches |
| FORIOT LCR-TC1 | LCR and transistor tester | Not stated | ESR indication named; no span | Not stated | Not stated | Compact; no figures stated |
| diymore LCR-TC1 style | LCR and transistor tester | Not stated | Not confirmed on the listing | Not stated | Not stated | Compact; no figures stated |
Product reviews
FNIRSI LC1020E 100kHz LCR Meter, 19,999 Counts
A bench LCR meter that shows ESR next to other readings. The listing states a 19,999-count display, five test frequencies (100Hz, 120Hz, 1kHz, 10kHz and 100kHz), adjustable test voltage of 0.1/0.3/0.6V, internal bias of 0.0/0.5V, and main and secondary parameters X/D/Q/θ/ESR shown together. Ranges are capacitors 1pF-100mF, resistors 10mΩ-10MΩ and inductors 1µH-100H. It has a 2.8 inch TFT display, a 3000mAh battery with Type-C charging and auto-off, 3-pin sockets and 5-slot jacks for four-terminal measurements. It weighs 250 g and measures 3.35 x 1.38 x 7.28 inches.
Who it suits: A bench user sorting mixed parts who wants to compare ESR at chosen frequencies.
Pros
- Five test frequencies and low selectable test voltages.
- Capacitance, resistance and inductance in one tool.
- Four-terminal fixtures for low-ohm work.
Cons
- Open/short calibration and full discharge are required.
- The listing warns not to measure live circuits.
- No ESR ohm span is stated.
Skip if: you want a one-button board sweeper with a simple good or bad beep.
View the FNIRSI LC1020E on Amazon (affiliate link)
Signstek MESR-100 V2 ESR Meter and Low Ohm Meter, 0.01R-100R
A simple dedicated meter for fast capacitor ESR and low-ohm checks. The title states 0.01R-100R, and the bullets describe dual terminals, auto-ranging capacitor ESR and low-ohm measurement, an upgraded test clip and a printed ESR table for a quick compare. The item weighs 8 ounces and is battery powered.
Who it suits: A repair hobbyist who wants two leads, auto-ranging and a table to compare readings against.
Pros
- Fast to use: clip on, read, compare with the table.
- Low-ohm range from 0.01R.
- Light at 8 ounces.
Cons
- No test frequency, test voltage or capacitance span is stated.
- No CAT rating is stated.
- In-circuit use is not stated, so check before using it on dense boards.
Skip if: you need a capacitance value or stated frequency control.
View the Signstek MESR-100 V2 on Amazon (affiliate link)
GME Professional In-Circuit ESR Capacitor Tester
The clearest in-circuit ESR tester in this set. It states ESR measurement of capacitors from 0.47µF to 2200µF in or out of circuit, with a microprocessor-generated 100 kHz test frequency and a low 15 mVp-p test voltage that will not turn on solid state devices. It also states automatic discharge of the capacitor under test, automatic calibration on power up and one-handed tweezers with gold plated tips. Power is battery or AC adapter. It weighs 16 ounces and measures 6 x 3.5 x 2 inches.
Who it suits: Someone repairing power supplies, monitors or amplifiers who wants to test capacitors on a powered-off board without unsoldering.
Pros
- Low test voltage suited to in-circuit checks.
- Auto discharge and auto calibration.
- Tweezers for one-handed scanning.
Cons
- Capacitance span is narrow, 0.47µF to 2200µF.
- No CAT rating stated.
- No ESR ohm span stated.
Skip if: you test very small film caps or very large motor caps outside 0.47µF to 2200µF.
View the GME in-circuit ESR tester on Amazon (affiliate link)
Velleman Atlas ESR70 Capacitance and ESR Meter
A meter that reads both capacitance and ESR, which helps when a capacitor reads near its value but still overheats. The bullets state suitability for any capacitor type between 1uF and 22000uF, an ESR range of 0.00 to 40.0 ohms with resolution as fine as 0.01 ohms, and audible alerts for different ESR levels. It weighs 0.1 kg and measures 5.51 x 7.87 x 1.18 inches.
Who it suits: A hobbyist or repair tech who wants capacitance and ESR on one screen for loose or removed parts.
Pros
- Stated ESR span and resolution.
- Audible alerts.
- Wide capacitance span, 1uF to 22000uF.
Cons
- Test frequency, battery type and CAT rating are not stated.
- Larger to store than a pocket tester.
Skip if: you need transistor pinout or inductance sorting in the same tool.
View the Velleman Atlas ESR70 on Amazon (affiliate link)
FORIOT LCR-TC1 Multi-Function Transistor and ESR Tester
A compact general component tester. Its title names a transistor tester, an LCR meter and an ESR tester with a TFT display, and the bullets describe measuring inductance, capacitance and resistance with an easy-to-read display. Power source is listed as Corded Electric and the style as Compact. No ESR range, resolution or test frequency is stated.
Who it suits: A beginner who wants one small tool for sorting inductors, capacitors, resistors and transistors, with ESR as a rough indication.
Pros
- One compact tool for several parts.
- TFT display.
Cons
- ESR range, resolution and frequency are not stated.
- No CAT rating stated.
- Not described as an in-circuit tester.
Skip if: you need a stated in-circuit ESR range or Kelvin-grade low-ohm accuracy.
View the FORIOT LCR-TC1 on Amazon (affiliate link)
diymore LCR-TC1 Style Transistor and Capacitor Tester
A compact, battery-powered multi-function tester in the LCR-TC1 style. The title describes an LCR meter and transistor tester for transistors and capacitors. The listing details here cover only the brand, power source and style, so an ESR range and in-circuit support are not confirmed. This is a general parts checker, a hobby sorting alternative rather than a proven ESR meter.
Who it suits: A hobbyist who wants a compact transistor and capacitor checker and will confirm ESR support on the listing first.
Pros
- Compact and battery powered.
- Covers transistors and capacitors per the title.
Cons
- ESR range and CAT rating are not stated here.
- In-circuit support is not stated.
Skip if: you need a stated ESR range or in-circuit support.
View the diymore LCR-TC1 style tester on Amazon (affiliate link)
How to choose an ESR tester
Start with where the capacitor lives. For boards you do not want to strip, choose a true in-circuit design with a low test voltage, auto discharge and a fast probe. For loose parts, choose a meter that reports capacitance plus ESR. For general hobby sorting, a component tester that reads transistors and inductors may be enough, but read its limits closely.
Choose a dedicated ESR meter if you chase bad electrolytics on power supplies, monitors, audio amps or motherboards. Choose an LCR meter with ESR if you also match inductors, check Q and D, or sort resistors. ESR changes with frequency, so compare parts at the frequency your procedure calls for, and do not treat readings taken at different frequencies as equal.
If you only need capacitance without ESR, see Best Capacitor Tester for HVAC and Electronics. For mains circuit tools, see Best Circuit Tester for Cars, Outlets and Breakers.
Buying checklist
- In-circuit support: yes or no in the listing.
- Capacitor span: GME 0.47µF to 2200µF, Velleman 1uF to 22000uF, FNIRSI 1pF to 100mF.
- ESR span and resolution: only the Velleman (0.00 to 40.0 ohms, 0.01 ohm) and the Signstek title (0.01R-100R) give numbers.
- Test frequency and test voltage: GME 100 kHz at 15 mVp-p, FNIRSI five frequencies and 0.1/0.3/0.6V.
- Probes: tweezers, clips, sockets or four-terminal jacks, and whether they reach your parts.
- Power: FNIRSI rechargeable 3000mAh, GME battery or AC adapter, FORIOT corded.
- Safety: power off, discharge, then measure. None of these states a CAT rating.
Size and carry check
The FNIRSI is 250 g and 3.35 x 1.38 x 7.28 inches, the GME is 16 ounces and 6 x 3.5 x 2 inches, the Velleman is 0.1 kg and 5.51 x 7.87 x 1.18 inches, and the Signstek is 8 ounces. Check which dimension is length before comparing sizes.
FAQ
What does an ESR tester measure?
It measures equivalent series resistance in a capacitor. The Velleman lists a 0.00 to 40.0 ohm span with 0.01 ohm resolution, and the Signstek title claims 0.01R to 100R. A capacitance reading alone does not replace the ESR value when you troubleshoot an electrolytic capacitor.
Can an ESR tester check a capacitor in circuit?
Only count on it when the listing says so. The GME states testing from 0.47µF to 2200µF in or out of circuit, using a 100 kHz signal at 15 mVp-p. Other listings here do not state in-circuit support. Power off the board, discharge the capacitor and follow the manual.
Why does ESR test frequency matter?
ESR changes with frequency, so a reading needs a stated test condition. The FNIRSI offers 100Hz, 120Hz, 1kHz, 10kHz and 100kHz, and the GME uses 100 kHz. Compare parts at the frequency your procedure calls for.
Do I need Kelvin clips for ESR testing?
Four-terminal fixtures help separate lead resistance from very low readings. The FNIRSI has 3-pin sockets and 5-slot jacks for four-terminal work, while the GME uses one-handed tweezers with gold plated tips. Pick fixtures that physically reach your parts.
Can I use an ESR tester on a live circuit?
No. None of these listings states a CAT rating, and the FNIRSI listing warns against measuring live circuits. Discharge capacitors, confirm the circuit is dead with proper equipment, then measure. Panel and service work belongs to a licensed electrician.
Should I buy a dedicated ESR meter or an LCR meter?
Choose a dedicated meter such as the GME for fast powered-off board scanning. Choose an LCR meter such as the FNIRSI when you also need capacitance from 1pF to 100mF, resistance from 10mΩ to 10MΩ, inductance from 1µH to 100H and selectable frequencies.
Final note
Choose the GME for powered-off in-circuit board work, the FNIRSI LC1020E when you also need capacitance, resistance and inductance with selectable frequencies, and the Velleman Atlas ESR70 for a capacitance and ESR meter with a stated ESR span. The Signstek suits quick low-ohm checks with a printed ESR table. Treat the FORIOT and diymore as hobby component testers until you confirm their ESR details on the listing. Do not use any of them on mains.
