Innova 3320 Auto-Ranging Digital Multimeter
Priced as of May 21, 2026
4.5(7,549 ratings)Buy on AmazonSaved to your guest loadout. Sign up to also save to your Cabinet (consumables) or Kit (tools you own).
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Prices may varyCarCareTruth's Analysis
Last reviewed May 21, 2026
TL;DR Averaged-response meter (not True-RMS) — reads accurately on DC battery voltage and clean sine-wave AC but will underread by 10–15% on PWM-controlled automotive loads. The Amazon listing claims UL certification but declares no CAT installation category (CAT II/III/IV) — buyers have no rated category to evaluate the meter against the circuits they intend to probe. The color-coded green/yellow/red LED battery-check is a genuinely useful 3320-specific feature for household batteries.
What it is and how it performs
The Innova 3320 is an auto-ranging digital multimeter with a 10 MΩ input impedance and an averaged-response measurement circuit. No True-RMS designation appears anywhere in the Amazon listing — averaged-response is the correct read. AC and DC voltage, DC current, and resistance are visible on the rotary dial in the main product photo. The manufacturer claims UL certification, but no CAT installation category is declared in the listing and no UL listing number is published — UL Product iQ database verification is deferred. Color-coded LEDs (green / yellow / red) provide a quick household battery state-of-charge readout, which is the 3320's distinctive feature versus the 3340 sibling. Backlight presence is not documented in the listing.
Who should buy this — and who should skip it
A home owner who wants a basic auto-ranging meter for checking household battery state-of-charge, 12V automotive battery voltage, fuses, and simple continuity will find the 3320 adequate. Fifteen years of continuous Amazon sales (7,549 reviews at 4.5 stars) is real durability signal. Skip it for any work that touches household AC outlets, breaker panels, or modern PWM-controlled automotive circuits — the undeclared CAT class is a real evaluative blocker for AC work, and the averaged-response circuit gives wrong answers on PWM loads. The Innova 3340 (CAT II 600V, UL Listed cULus 4Z93) or a Fluke / Klein independently certified meter is the better tool for those use cases.
Safety and environmental impact
The 3320 carries a manufacturer UL claim (feature bullet and Amazon specifications) but no CAT installation category is declared in the Amazon listing and no UL listing number is published — UL Product iQ database verification is deferred (2026-05-20). The Amazon listing also carries a California Proposition 65 warning (common for electronic test equipment housings and solder). No CPSC recall is active (CPSC.gov search 2026-05-20) and no fire or arc events surfaced across 7,549 reviews spanning 2011–2026. Runs on a standard 9V alkaline battery; Call2Recycle drop-off locations handle alkaline battery disposal, and the meter housing is standard e-waste recyclable at Best Buy, Staples, or municipal e-waste collection.
Frequently asked questions
Is the Innova 3320 True-RMS?▾
No. The 3320 uses an averaged-response measurement circuit. No True-RMS designation appears in the product title, feature bullets, description, or Amazon specifications. For DC battery voltage, alternator output, and clean sine-wave AC, an averaged-response meter reads accurately. On PWM-controlled circuits (fans, lighting drivers, motor controllers, modern vehicle control modules) it will underread by 10–15% compared to the actual signal. For checking battery voltage, fuses, and simple 12V automotive circuits, the limitation usually does not matter.
What CAT rating does the Innova 3320 have?▾
No specific CAT installation category (CAT I, II, III, or IV) is declared in the Amazon listing — not in the title, the feature bullets, the description, or the specifications. The manufacturer states the product is 'UL certified' and Amazon specifications list 'Specification Met: UL', but no UL listing number is published in the Amazon listing data and no CAT class is named. Without a declared CAT rating, buyers cannot evaluate the meter against the circuit they intend to probe. For probing anything connected to household AC, choose a meter with an explicit declared CAT II 600V or higher rating.
What is the difference between the Innova 3320 and the 3340?▾
The 3320 is the entry-level auto-ranging multimeter; the 3340 is the professional automotive variant. The 3340 adds an inductive RPM clamp (including coil-on-plug vehicles), a K-type temperature probe, dwell angle, duty cycle, frequency, continuity beep, and a carrying case. The 3320's differentiator is the color-coded green/yellow/red LED battery-check indicator for household batteries — a feature the 3340 does not include. The 3340 explicitly declares CAT II 600V certification with a visible UL listing number on the meter body; the 3320 does not declare a CAT class in its Amazon listing.
Does the Innova 3320 measure DC current?▾
Yes. DC current ranges are visible on the rotary dial in the main Amazon product image. The Amazon feature bullets and description focus on voltage, resistance, and the 10 MΩ input impedance but do not enumerate current ranges. The maximum current path is not stated in the Amazon listing — confirm against the printed legend on the meter face or the included manual before measuring current.
From the manufacturer
Marketing copy from Innova, via Amazon. Not editorial.
- •UL certified product designed to safely and accurately troubleshoot a variety of automotive and household electrical problems
- •Auto-ranging scales automatically selects correct measurement range and eliminate the need to dial in the correct range when making electronic measurements
- •Features large digital display and color coded LED's to easily check the charge status of batteries
- •Single-setting resistance function for AC and DC voltage
- •10 MegOhm input impedance; safe for electrical and automotive use; prevents damage to the vehicle’s ECU
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Manufacturer videos
Manufacturer images
Manufacturer specifications
- Brand
- Innova
- Power Source
- Battery Powered
- Style
- 3320
- Color
- Red & Black
- Item Weight
- 8 ounces
- Measurement Type
- Multimeter
- Compatible Devices
- Automotive electrical components, household electrical components, batteries, solar panels, fuses, wiring, and other electrical circuits
- Style Name
- 3320
- Item Dimensions
- 2 x 10 x 5 inches
- Specification Met
- UL
- Brand Name
- Innova
- Model
- 3320
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