kW vs kWh: What's the difference?

kW measures power. kWh measures energy. The simplest way to remember: power is how fast, energy is how much.

The water tank analogy

Imagine water flowing from a tap into a bucket:

• kW is the rate of flow — litres per second.
• kWh is the total water collected — litres in the bucket after an hour.

A tap running at 1 litre/second for 1 hour fills 3,600 litres. Similarly, an appliance drawing 1 kW running for 1 hour consumes 1 kWh.

Your bill is in kWh (called "units")

When your bill says "units", it means kWh. Every unit is 1,000 watts running for 1 hour. Examples:

• A 2 kW geyser run for 30 minutes = 1 unit.
• A 100 W ceiling fan run for 10 hours = 1 unit.
• A 1.5 ton 3-star AC drawing 1.6 kW, run 8 hours = 12.8 units/day.

Sanctioned load is in kW

Your sanctioned load — listed on the bill — is the maximum kW your connection is permitted to draw at any moment. Fixed charges usually scale with it (₹/kW/month).