This document provides a comprehensive guide on how to read and use vernier calipers, detailing their anatomy and functions. Key components include the main scale, vernier scale, fixed jaw, sliding jaw, depth rod, locking screw, and thumb wheel, which facilitate precise measurements. The document also outlines a step-by-step process to accurately take and read measurements, ensuring proper calibration and calculation of readings.

1. VERNIER CALIPER
How To Read Vernier Calipers:
A Step-By-Step Guide

2. ANATOMY OF VERNIER CALIPERS
Understanding the anatomy of vernier calipers is the first step towards mastering its use. A vernier caliper
comprises 7 parts, each designed to perform specific functions essential for accurate measurement.

3. ANATOMY OF VERNIER CALIPERS
The main scale: Typically etched onto the caliper's body, is your primary reference
point for measurement. It typically features two sets of units: one in millimetres
(mm) for metric measurements and another in inches for imperial measurements,
ensuring versatility across different measurement standards with the same tool.
The vernier scale: is a smaller, sliding scale that moves
along the main scale. It provides the fine measurement
increments needed for a precision reading. Using the vernier
scale in conjunction with the main scale allows for accuracy
down to fractions of a millimetre or thousandths of an inch.
The fixed jaw: is attached to the caliper's body and serves as
the stationary reference point for both external and internal
measurements. It's meticulously machined to ensure flatness
and precision.
The sliding jaw: attached to the vernier scale, works in
tandem with the fixed jaw to provide the measuring area. It
can clamp around an object's exterior for external
measurements or expand into an object for internal
measurements.
Depth rod: Emerging from the end of the caliper is the depth

4. ANATOMY OF VERNIER CALIPERS
The locking screw: is a crucial feature that secures the sliding jaw in place once
the desired measurement is taken. This ensures the measurement does not change
due to accidental movement while reading or recording the measurement.
Thumb Wheel: Adjacent to the sliding jaw, some calipers also
have a thumb wheel for fine adjustment of the jaw's position.
This feature facilitates smooth and precise jaw sliding for
accurate measurements in a far more ergonomic fashion also
allowing for one-handed use.
Understanding this anatomy is crucial for taking accurate
measures with calipers. With this foundation, we can move on
to learning how to read a vernier caliper accurately.

5. HOW TO READ A VERNIER CALIPER
1. Zero Calibration
Before measuring, ensure that the caliper is correctly calibrated. Close the jaws fully, and
check if the zero marks on the main scale and vernier scale align. If not, you may need to
recalibrate or adjust for zero error.

6. HOW TO READ A VERNIER CALIPER
2. Taking the Measurement
For external dimensions, place the object (such as a screw) between the fixed and sliding jaws.
For internal dimensions, use the internal measuring jaws. If measuring depth, extend the depth
rod into the hole or recess. Gently close the jaws or extend the rod until it snugly fits the
dimension you are measuring.

7. HOW TO READ A VERNIER CALIPER
3. Reading the Main Scale
Note the last visible mark on the main scale that lines up with the vernier scale's zero. This is
your main scale reading. In this example, 3 as the zero point of the vernier scale has not yet
passed the 4th indicator.

8. HOW TO READ A VERNIER CALIPER
4. Reading the Vernier Scale
Next, look for the line on the vernier scale that vertically aligns perfectly with a line on the main
scale. There should only be one. This is your vernier scale reading. The divisions on the
vernier scale will give you your measurement past the decimal point.
A simple scenario would be if the division indicator marked as 9 on the vernier scale lines up
perfectly, that would be 0.9mm. In our scenario, the line that aligns perfectly is the 2nd after 9.
Because each division denotes 0.02mm as indicated by the caliper, this would be 0.94mm.

9. HOW TO READ A VERNIER CALIPER
5. Add Your Main & Vernier Scale Together
Now that you’ve got your main and vernier scale reading, all that’s left to do is add them
together to get your final reading.
So, (Main Scale) 3mm + (Vernier Scale) 0.94mm leaves us with a reading of 3.94mm.

10. HOW TO READ A VERNIER CALIPER IN “MM”
In this example, the last visible mark on the main scale is 7mm, and the vernier scale line that aligns
perfectly with a main scale line is the one just after the 1 numbered indicator marking.
Knowing that the least count of the caliper is 0.02mm (your caliper may vary) we can safely say that the
1 marking is 0.1mm plus the one additional marking past it which is the one that lines up vertically, so,
0.12mm.
We can also calculate the reading using the formula, as we know that the marking that lines us is the
6th sequentially and the least count is 0.02mm.
Total Measurement = 7mm + (6 × 0.02mm)
= 7mm + 0.12mm
= 7.12mm