How do electric meters read your bills?

Learn how electric meters work to track your energy usage and calculate your electricity bill accurately.

You must have been asked to switch off lights and fans while leaving a room and lectured about how the electricity bill will skyrocket. Have you ever wondered how the electricity meter or the watt-hour meter works? How do we understand how much electricity we have consumed and how much to pay? Let’s dive into the science behind this important adulting skill!

Before we go into the physics behind an electric meter, let’s understand what an electric meter is. An electricity meter is a device that keeps track of how much electricity your home uses. It works by measuring the flow of electricity through your house and converting it into a number that shows how much energy you’ve used. This number is then used to calculate the cost of electricity used by multiplying it by the unit cost of electricity in your region. 

Have you ever seen a small box on the side of your house with numbers or a screen on it? That’s an electric meter. Electricity flows into your house through wires. The meter is placed right where the electricity enters the house.

As the electricity flows through the meter, it records the amount of electricity used in something called kilowatt-hours (kWh). Kilowatt-hours is the unit in which the energy used is calculated.

When electricity travels from the power lines into your home, it first goes through the electric meter. The meter is like a gate that checks how much electricity is passing through. Inside the meter, there are special parts that detect and measure the flow of electricity. Depending on the type of meter, this works in different ways.

Analogue meters have a metal disc inside that spins when electricity flows. As the electricity flows, it makes a little disc inside the meter spin faster or slower depending on how much electricity is being used. The spinning turns gears connected to little dials that show how much electricity has been used. A designated official has to come and read the number on an analogue meter.

The major working principle behind an analogue electric meter is known as Electromagnetic Induction. The main parts and processes include: