Vernier Caliper For Lab Measurement

Vernier Caliper

Four-Way Measurement: Capable of measuring outside diameter, inside diameter, depth, and steps with a single tool.

Thumb Roll & Locking Screw: Features a knurled thumb roll for smooth, micro-adjustments and a locking screw to secure the measurement for accurate reading.

$3.33

Quick Answer: A vernier caliper is a sliding measuring instrument with a main scale on a fixed beam and a short vernier scale on a moving jaw. It reads outside diameters, inside diameters, depths and steps more finely than a plain ruler allows.

Reading Between the Millimetre Marks

The main scale on the beam is graduated like a rule. The sliding jaw carries a second, shorter scale whose divisions are slightly smaller than those of the main scale, so only one vernier line lines up exactly with a main-scale line at any setting. The main-scale mark just before the vernier zero gives the coarse reading; the number of the vernier line that coincides, multiplied by the least count, gives the fraction to add.

Least count is worked out before measuring, not assumed. Divide the value of one main-scale division by the number of vernier divisions: if ten vernier divisions span nine main-scale millimetres, each vernier division is 0.9 mm and the least count is 0.1 mm. Instruments with more vernier divisions read finer steps, so read these numbers off the caliper in front of you.

Close the jaws fully before starting. If the vernier zero sits to the right of the main-scale zero, the error is positive and is subtracted from every reading; if it sits to the left, it is negative and is added back. For a direct numerical readout, the digital caliper in the same range removes the line-matching step, while density practicals often pair this instrument with a set of density blocks.

Specifications

Instrument	Sliding caliper with main and vernier scales
Measurements	Outside, inside, depth and step
Jaws	Large lower jaws for outside work; small upper jaws for bores
Depth	Thin rod sliding out from the end of the beam
Locking	Screw on the sliding jaw to hold a reading (usual design)
Range, least count and material	Confirm at enquiry

Applications

Measuring the diameter of a pendulum bob so the effective length of a simple pendulum can be found
Finding the internal diameter and depth of a beaker or calorimeter to calculate its volume
Measuring the length and diameter of a small metal cylinder for a density calculation
Checking slot widths and plate thicknesses in workshop practice

Care & Handling

Close the jaws gently on the object; forcing them tilts the slider and gives a reading larger than the true size.
Look straight down on the coinciding lines to avoid parallax.
Wipe the beam clean and dry before storing, and leave the jaws slightly apart so the measuring faces do not rub.
Do not use the jaw tips as a scriber, compass point or screwdriver.

Why Choose LabEquip

Schools buying for class practicals usually order one caliper for each pair or small group of students, and colleges add a few for project work. LabEquip lists this model in the General Lab Products range beside plastic, stainless steel and digital versions; share the number of workstations on the contact page.

Frequently Asked Questions

How do I find the least count of a vernier caliper?

Divide the smallest main-scale division by the total number of divisions on the vernier scale. For example, 1 mm divided by 10 vernier divisions gives 0.1 mm, and 1 mm divided by 50 gives 0.02 mm. Always take these numbers from the instrument you are using.

What is zero error and how is it corrected?

With the jaws closed, the vernier zero should line up with the main-scale zero. If it lies to the right, the zero error is positive and is subtracted from readings; if it lies to the left, it is negative and its size is added. Note it before each set of measurements.

Which jaws measure the inside of a tube?

The two small jaws on the top edge. Insert them into the bore, open them until they touch opposite walls, and lock the slider before lifting the instrument out. The large lower jaws are for outside diameters and thicknesses.

How is depth measured?

Rest the end of the beam on the rim of the hole or container and move the sliding jaw until the thin depth rod touches the bottom. Keep the beam upright, because a tilted rod travels further than the true depth and overstates it.

Is a vernier caliper better than a micrometer?

Each suits different work. A caliper covers a longer range and also measures bores and depths. A micrometer screw gauge reads finer steps over a short range, usually outside sizes only, so it is chosen for wire diameters and thin sheets.

Why do two students get different readings for the same object?

Common causes are uneven jaw pressure, an unlocked slider, parallax when judging which lines coincide, and a forgotten zero correction. Averaging three readings taken at different places on the object also reduces the effect of an irregular shape.

Last Updated: September 2026