“Units and Measurements” is one of the most asked topics in the Static GK – Science & Technology section of competitive exams like SSC, Railways, CDS, NDA, Banking, and State PSCs.

In science, we measure everything — length, time, mass, temperature, electric current, and many other quantities.
To compare and communicate measurements accurately, scientists use standard units, which are the same everywhere in the world.

This system of measurement is called the SI System (International System of Units).

Here’s a complete, simple, and exam-focused article on Units and Measurements — written in clear English for easy understanding

What are Units?

A unit is a standard quantity used to measure physical quantities.
For example:

• Length → measured in metres (m)
• Time → measured in seconds (s)
• Mass → measured in kilograms (kg)

Units ensure that everyone understands measurements in the same way across the world.

Types of Physical Quantities

SI Units (Systeme Internationale d’Unités)

The SI system is the internationally accepted standard system of measurement.
It was established in 1960 by the General Conference on Weights and Measures (CGPM).

Fundamental SI Units

 Tip: These 7 are the base units — every other unit is derived from them.

Derived SI Units (with Examples)

Commonly Used Non-SI Units (and their conversions)

Prefixes Used in SI Units

 Trick to Remember:
King Henry Died By Drinking Chocolate Milk ☕
→ (Kilo, Hecto, Deca, Base, Deci, Centi, Milli)

Important Instruments and Their Measurements

Summary

• Units and measurements form the foundation of science.
• The SI system ensures that measurements are uniform worldwide.
• Understanding derived units, conversions, and instruments helps in solving basic numerical and factual GK questions.

“What cannot be measured, cannot be improved — that’s why units matter in science!”