Physics Figures Length Reading Generator
0–25 mm0.01 mm05303540450–25 mm0.01 mm0530354045

Ruler, caliper and micrometer figures for measuring length

The Length Reading Generator draws the instrument a length is read from: a centimeter or inch ruler with an object lying along it, a 150 mm caliper with its jaws open to the reading you type, or a 0–25 mm micrometer. Close-ups of the scales keep every mark readable in print.

The caliper reads to 0.1, 0.05 or 0.02 mm, and exactly one mark on its sliding scale lines up with the main scale. The micrometer reads to 0.01 mm at its marks, or to an estimated 0.001 mm between them, with its thimble’s marks bunching toward its edges as on a real one. Hold a block, cylinder, ball or wire in the jaws, give the instrument a zero error for a correction question, and turn on the answer key to print the reading.

What you can set

  • The instrument: a ruler, a caliper or a micrometer
  • A metric ruler, 15 to 100 cm long, or an inch ruler, 6 to 20 in long, how finely it is marked, and lengths read to one estimated digit or to the nearest mark
  • The object on the ruler, its length and where its left end sits, with magnifiers on its ends
  • The caliper’s least count: 0.1 mm (10 divisions over 9 mm), 0.05 mm (20 over 39 mm) or 0.02 mm (50 over 49 mm), printed on the slider or left off
  • The micrometer read to its marks, 0.01 mm, or to one estimated digit past them, 0.001 mm
  • The caliper or micrometer reading, typed or picked at random, and a zero error, with the instrument also drawn closed
  • In the jaws: nothing, a block, a cylinder, a ball or a wire, drawn to size, with a short label
  • The instrument with its close-up, the close-up alone, or the instrument alone
  • A chart title, and an answer key line with the reading and any correction

Copying, printing and sharing

Copy the figure straight into a test, worksheet or slide, or download it as a PNG or SVG. Printing the page prints just the figure. Share link copies the page’s address with your settings in it, so anyone who opens it sees this exact figure, and presets save settings you use often in your browser. It’s free, with no sign-up.

Example figures

Frequently asked questions

How do you read a caliper?

Read the main scale at the sliding scale’s zero: the last millimeter mark before it. Then find the one mark on the sliding scale that lines up exactly with a main-scale mark, and add that many least counts. With the zero just past 23 mm and the 9th mark of a 0.05 mm scale lined up, the reading is 23 + 9 × 0.05 = 23.45 mm.

What is the least count of a caliper?

The smallest length it can read: one main-scale division less one division of the sliding scale. Ten divisions over 9 mm are 0.9 mm each, so the least count is 1 − 0.9 = 0.1 mm. Twenty over 39 mm (1.95 mm each, against 2 mm on the main scale) give 0.05 mm, and fifty over 49 mm give 0.02 mm.

How do you read a micrometer?

Read the last mark showing on the sleeve: whole millimeters above the datum line, and the half-millimeter mark below it if it has appeared. Then add the thimble mark on the datum line, 0.01 mm each. A sleeve showing 7 mm and thimble mark 38 read 7.38 mm; with the 7.5 mark showing as well, 7.88 mm. When the datum line falls between two thimble marks, estimate how far, in tenths of a mark, for one more digit: 0.4 of the way from mark 38 to mark 39 reads 7.384 mm.

What is a zero error?

With its jaws closed, a caliper or micrometer should read zero. If it doesn’t, the reading it shows closed is the zero error, positive or negative, and you subtract it from every reading: an instrument that reads +0.10 mm closed and 23.45 mm on a block measures 23.35 mm. Turn on Also show it closed to draw the closed instrument above the measuring one.

How do you measure with a ruler to the right number of significant figures?

Read to the smallest mark, then estimate one more digit. On a ruler marked in millimeters, that means reading to 0.01 cm, like 4.37 cm. On a ruler marked only every centimeter, read to 0.1 cm.

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