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How to Zero a Digital Caliper and Micrometer

Guide · Updated October 27, 2026

A wrong zero shifts every reading by the same amount. Zeroing takes seconds, but only if the faces are clean and you close them the same way every time.

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Step by step

Clean the faces: Wipe the jaws or anvils with clean paper or lint-free cloth.
Close consistently: Close the caliper jaws with light thumb pressure. On a mic, use the ratchet or friction thimble with 2 to 3 clicks.
Set zero: Press zero or origin on a digital tool, or adjust the sleeve on a mechanical mic.
Verify: Measure a gage block. The reading should match the block size.
Re-check: Re-zero after a battery change, a drop or a big temperature change.

Zero that drifts

Weak batteries cause jumping readings.
Coolant or dirt in a caliper's scale throws readings off.
Loose caliper gibs give inconsistent readings.

Larger mics

Zero a 1–2 in or bigger mic on its standard, or on a gage block stack.

Worked example: checking zero with a gage block

After zeroing a 0–1 in micrometer with the faces closed, measure a 0.5000 in gage block. A reading of 0.5001 in is within the typical ±0.0001 in accuracy for an inch micrometer. For a 0–6 in digital caliper, check zero closed and then a 1.0000 in block; typical accuracy is ±0.001 in.

If the micrometer reads 0.0002 in at zero, adjust the sleeve with the spanner wrench rather than recording an offset. Clean faces by closing on paper and drawing it out.

Fuller worked example: checking zero against a standard

A 1–2 in micrometer closed on its 1.0000 in setting standard reads 1.0002 in. The zero error is +0.0002 in, so either reset the barrel with the spanner until it reads 1.0000 in, or subtract 0.0002 in from every reading until you do. Repeat three closures with the ratchet; readings that wander more than 0.0001 in point to dirty faces or inconsistent force.

For a caliper, zero with the jaws clean and closed, then check a 1.000 in gage block. A reading of 1.001 in means the jaws or scale are out; re-zero and check again at 2.000 in and 4.000 in (e.g. 1.000 + 3.000 in blocks) to see if the error grows with length.

FAQ

How do I zero a digital caliper?

Clean the jaws, close them with light, consistent pressure and press zero. Then verify on a gage block.

How do I zero a micrometer?

Clean the anvils, close with the ratchet and adjust the sleeve or press zero. Use a standard for mics over 1 in.

Why won't my caliper hold zero?

Usually weak batteries, a dirty scale or loose gibs.

How do I check accuracy after zeroing?

Measure gage blocks across the range. Build the sizes free at gageblockcalc.com.

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General shop information only — follow your gage manufacturer's instructions and your quality system.