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Metric or imperial dial caliper

Updated: 22 October 2026

The amazon.co.uk title said 150 mm, the parcel is open, and the needle does not look like the millimetre dial you expected. Two different problems feel the same at that moment. One is an inch face sold under a metric description. The other is a genuine metric dial that moves 2 mm in one turn, so the needle seems to race. This page is the check for a metric or imperial dial caliper before you trust a size or start a return. The three listings are on the [Dial caliper](/hub/measuring-and-marking-tools/dial-caliper) comparison. Peter F. used the United Kingdom review notes. A qualifying purchase can earn a commission at no extra cost to you.

The amazon.co.uk title said 150 mm, the parcel is open, and the needle does not look like the millimetre dial you expected. Two different problems feel the same at that moment.

Our top picks

Mitutoyo Mitutoyo 505-732 dial caliper

Best overall

Mitutoyo Mitutoyo 505-732 dial caliper
9.3/10about £86.71
View offer
Standard Gage Standard Gage dial caliper, 150 mm

Best value

Standard Gage Standard Gage dial caliper, 150 mm
9.3/10about £45.99
View offer
Hyuduo Hyuduo plastic dial caliper, 150 mm

Alternative

Hyuduo Hyuduo plastic dial caliper, 150 mm
5.4/10about £12.71
View offer
On this page
  1. 1.Two ways a dial feels wrong
  2. 2.What the £12.71 listing's UK reviews report
  3. 3.A 2 mm turn can still be metric
  4. 4.If the face does not match the title

Two ways a dial feels wrong

Read the centre of the dial before you believe the title. You are looking for inches, or for 0.1 mm, 0.02 mm or 0.01 mm, and for how far one full turn moves the jaws. Inch workshop dials are often 0.001 inch per division. A metric 0.02 mm dial is a DT-type: one revolution is 2 mm. A metric 0.01 mm dial is a DE-type: one revolution is 1 mm. Those two metric faces are not inch faces that you should convert in your head. On a 2 mm-per-turn dial the needle passes zero twice while the jaws open 2 mm. A second set of figures on the face is the second millimetre of that revolution. It is not a negative reading. If the centre says inches, or one turn of the needle is one inch, do not multiply that reading and then machine a metric fit.

What the £12.71 listing's UK reviews report

The Hyuduo plastic dial, ASIN B07TM8JKXT, is the inch problem in this set. It is listed at £12.71 and 91 g. The title and bullets say 0–150 mm. The accuracy field says ±0.05 mm. Amazon shows 2.7 from 25 reviews. Several United Kingdom reviews say the yellow dial they unpacked reads inches, one turn per inch. The title is not proof of a metric dial. One UK reviewer then received a white dial under the same description, one turn per 10 mm with 0.1 mm marks, and raised that example to 4 stars. For a machined metric size, this is the listing to skip. Who should skip it for real work is on best dial caliper.
Mitutoyo Mitutoyo 505-732 dial caliper

Testsieger

Mitutoyo Mitutoyo 505-732 dial caliper
9.3/10about £86.71
View offer

A 2 mm turn can still be metric

Do not return a correct metric dial because the needle feels fast. The National Physical Laboratory's DT-type is the ordinary 0.02 mm workshop dial: 2 mm per revolution, and each mark 0.02 mm. On the Standard Gage listing, ASIN B0DB29M9M7, at £45.99, the bullets say metric millimetres, 0–150 mm, resolution 0.02 mm and ±0.02 mm. One review says one turn is 2 mm because the gearing follows an inch layout remarked for metric. If the centre says 0.02 mm, add the beam to that fraction. Reviews of the Mitutoyo 505-732 listing, ASIN B0142HWZSG, at £86.71, describe a yellow face, 0.01 mm marks and one full turn per millimetre. The listing's accuracy bullet is still 0.002 in. That inch line is not proof that the dial in the box is imperial.

If the face does not match the title

If the title states millimetres as a main characteristic and the dial in your hand is graduated in inches, the description and the goods have parted company. Section 11 of the Consumer Rights Act 2015 makes the description a term of the contract. Section 19 sets out the remedies. Keep the tool as it arrived while you take that up with the seller. Photograph the centre of the dial, the beam scale, and the Amazon title and accuracy line. A yellow one-turn-per-inch face against a 0–150 mm title is a different photograph from a 0.02 mm face whose needle passes zero twice in 2 mm. When the unit is the one you wanted, learn the sum on how to read a dial caliper.

Common questions

How do you tell an inch dial from a metric dial on the face?
Read the centre. An inch dial is often marked 0.001 inch per division, and United Kingdom reviews of the £12.71 plastic listing describe a yellow face with one turn per inch. A metric dial is marked 0.02 mm, 0.01 mm or, on one white example from that same listing, 0.1 mm. The centre of the dial is the unit you will actually add.
Can two dials share one Amazon listing?
Yes. On B07TM8JKXT, United Kingdom reviews describe a yellow inch dial, one turn per inch, and a later white metric dial, one turn per 10 mm with 0.1 mm marks, under the same millimetre title. The title cannot prove which face will arrive. Read the centre when you unpack, and photograph it if it is not the unit the listing stated.
What does the law say if the title says millimetres and the dial says inches?
Section 11 of the Consumer Rights Act 2015 makes the description part of the contract, including a main characteristic such as the unit. Section 19 sets out the remedies. It does not apply to a metric 0.02 mm dial that simply turns 2 mm per revolution.
Does a 0.002 in accuracy line mean the Mitutoyo dial is imperial?
Not by itself. The amazon.co.uk listing B0142HWZSG states 0.002 in, while reviews describe a yellow metric face in 0.01 mm with one turn per millimetre. The inch line is a specification conflict with Mitutoyo UK's millimetre shop page. It is not proof that the needle is an inch dial. Do not merge the listing with the £168 shop specification.
What should you photograph before you contact the seller?
Photograph the dial centre, the beam scale, and the listing title plus the accuracy line. Those pictures separate an inch face from a 2 mm metric turn. Keep the tool as received. Do not convert an inch reading and then use that conversion as the size.

Related pages

Dial caliper buying guide

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How to read a dial caliper: beam first, then the dial

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Sources

Public sources listed for this comparison, checked against the 20 October 2026 shelf notes. Prices, stars and review counts for the three ASINs are the amazon.co.uk figures in that set. We did not run a lab test.

  1. NPL MGPG 40, calliper guide (retrieved October 2026)
  2. BSI BS EN ISO 13385-1:2019 (retrieved October 2026)
  3. ISO 13385-1:2019 (retrieved October 2026)
  4. Mitutoyo UK 505-732 (retrieved October 2026)
  5. Mitutoyo dial caliper instructions (retrieved October 2026)
  6. Wonkee Donkee, reading a metric dial caliper (retrieved October 2026)
  7. RS PRO 150 mm dial caliper 307-4666 (retrieved October 2026)
  8. Consumer Rights Act 2015, section 11 (retrieved October 2026)