Clamp meters and multimeters / Compared

Klein Tools CL390vsMilwaukee 2237-20

Two clamp meters, compared from their makers' published US specs. Specs checked 2026-10-17. Makers do not always rate the same way, so treat cross-brand figures with care.

Klein Tools CL390

CLAMP METER

Safety rating CAT III 600 VAC current 400 ADC current 400 A

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Find CL390 prices on Amazon Find CL390 prices at Acme Tools Opens the retailer in a new tab; the current price is shown there. Marketplace sellers vary: check the seller and exact model.

Milwaukee 2237-20

CLAMP METER

Safety rating CAT III 600 VAC current 600 ADC current 600 A

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Find 2237-20 prices on Amazon Find 2237-20 prices at Acme Tools Opens the retailer in a new tab; the current price is shown there. Marketplace sellers vary: check the seller and exact model.

How to choose between them

Both carry the same published safety rating (CAT III 600 V), so the ranges and the box contents are the decision.
Clamping large conductors or bundles? Jaw openings as published: CL390 1.6 in, 2237-20 1.3 in.
Cells: the CL390 uses 3 x AAA; the 2237-20 Alkaline (AA).
In the box: the CL390 comes with Carrying Case, Instructions, Test Leads; the 2237-20 with Test Lead Set, 2x AA Batteries, Manual.

From the published figures only; no testing. Rated figures from different makers are not measured the same way.

Where they differ

Milwaukee 2237-20: higher AC current range (600 A vs 400 A).
Milwaukee 2237-20: higher DC current range (600 A vs 400 A).
Klein Tools CL390: larger jaw opening (1.6 in vs 1.3 in).

12 of 17 listed specs differ or are listed by only one maker. Stated from the published figures only; no testing.

Every published spec, side by side

Spec	Klein Tools CL390	Milwaukee 2237-20
Safety rating (IEC 61010 CAT)	CAT III 600 V	CAT III 600 V
AC current, max rangeDiffers2237-20: +200 A (+50.0%)	400 A	600 A
DC current, max rangeDiffers2237-20: +200 A (+50.0%)	400 A	600 A
AC voltage, max range	600 V	600 V
DC voltage, max range	600 V	600 V
True-RMS	Yes	Yes
Jaw openingDiffersCL390: +0.3 in (+23.1%)	1.6 in	1.3 in
Display resolutionOnly one listed	4,000 counts	Not on maker page
Batteries (cells)Differs	3 x AAA	Alkaline (AA)
Resistance, max rangeDiffers	40 MΩ	6 kΩ
Capacitance, max rangeOnly one listed	4,000 μF	Not on maker page
Frequency, max rangeOnly one listed	60 kHz	Not on maker page
Temperature measurementOnly one listed	-40° - 1,832°F (-40° - 1,000°C)	Not on maker page
Non-contact voltage detection	Yes	Yes
Drop protectionOnly one listed	6.6 ft (2 m)	Not on maker page
SizeOnly one listed	8.45 x 3.5 x 1.5 in (L x W x H)	Not on maker page
Backlit displayOnly one listed	Not on maker page	Yes

"Differs" marks different published values; pure formatting is not counted. "Only one listed" marks a spec only one maker page gives. Box contents, owner ratings, manuals and sources are on each model's own page: CL390, 2237-20. Swap either model in the compare tool.