BVF's Insize digital caliper lists 0.01 mm resolution, while its digital outside micrometer lists 0.001 mm resolution. Compare the measuring range and the stated resolution or graduation separately, and ask for the model's accuracy specification before choosing an instrument for a tolerance check.
Caliper versus micrometer: specification chart
The chart uses the metric specifications in the BVF listings. “Resolution” and “graduation” follow the wording used for each product. The figures in the last column are not accuracy ratings.
| Instrument |
Insize model codes |
Listed ranges (mm) |
Stated reading increment |
| Digital caliper |
1112-150 / 200 / 300 |
0–150 / 0–200 / 0–300 |
0.01 mm resolution |
| Vernier caliper |
1205-1502S / 2002S / 3002S |
0–150 / 0–200 / 0–300 |
0.02 mm graduation |
| Dial caliper |
1312-150A / 200A / 300A |
0–150 / 0–200 / 0–300 |
0.02 mm graduation |
| Outside micrometer |
3203-25A to 3203-150A |
Separate 25 mm ranges, 0–150 total coverage |
0.01 mm graduation |
| Digital outside micrometer |
3109-25A / 50A / 75A |
0–25 / 25–50 / 50–75 |
0.001 mm resolution |
Reading the range correctly
The digital, vernier and dial caliper listings each offer 0–150, 0–200 and 0–300 mm options. Select the model that covers the dimension on your drawing, and check the variant code in the order.
The mechanical outside micrometer listing offers separate ranges: 0–25, 25–50, 50–75, 75–100, 100–125 and 125–150 mm. It does not describe one micrometer spanning 0–150 mm. The digital outside micrometer listing offers 0–25, 25–50 and 50–75 mm models.
For a part dimension of 40 mm, the listed 25–50 mm micrometer range includes that dimension. For a 60 mm dimension, check the 50–75 mm model. These are range comparisons only; confirm the instrument's suitability for the required inspection separately.
Resolution does not establish accuracy
Do not read 0.001 mm resolution as a promise of ±0.001 mm accuracy. Mitutoyo's caliper reference treats resolution and accuracy separately and explains that how the caliper is used affects the accuracy obtained.
For a tolerance-controlled job, request the exact model specification and the calibration information your inspection process requires. Compare those documents with the drawing's acceptance requirement rather than deciding from the display's decimal places alone.
What to check before buying
For a digital reading, compare the Digital Vernier Caliper - Insize with the Digital Outside Micrometer - Insize. For scale or dial options, see the Vernier Caliper - Insize, Dial Caliper - Insize and Outside Micrometers - Insize. The outside micrometer listings describe tools for measuring outside size.
- Write down the dimension and the tolerance to be inspected.
- Select the model code and range together.
- Request the accuracy specification for that exact model.
- Check the calibration documentation needed for your work.
- For calipers, close the jaws and check zero, then repeat the measurement to check consistency.
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