Home & Power
How Is Your Electricity Bill Calculated? Units, Slabs and Charges
How to count units for any appliance, a typical home's monthly use, how slab tariffs turn units into rupees, and the other charges on the bill.
By Team Vind · Updated · 5 min read
Your electricity bill is built on one number: units. A unit is one kilowatt-hour (kWh), the energy a 1,000-watt appliance uses in an hour. Once you can count units, you can check your bill, see which appliance costs the most, and work out what a new AC will add.
Step 1: units for each appliance
Units (kWh) = watts × hours used ÷ 1,000
A 1.5 ton inverter AC drawing about 1,200 W for 6 hours a day uses 1,200 × 6 ÷ 1,000 = 7.2 units a day, or about 216 units a month. A 70 W ceiling fan running 10 hours uses just 0.7 units a day.
A typical home's monthly units
| Appliance | Watts | How many | Hours a day | Units a month |
|---|---|---|---|---|
| Ceiling fans | 70 W | 3 | 10 | 63 |
| LED lights | 9 W | 6 | 6 | 10 |
| Refrigerator (average draw) | 60 W | 1 | 24 | 43 |
| LED TV | 80 W | 1 | 4 | 10 |
| 1.5 ton inverter AC | 1200 W | 1 | 6 | 216 |
| Geyser | 2000 W | 1 | 0.5 | 30 |
| Washing machine | 500 W | 1 | 0.5 | 8 |
| Total | 379 |
Try it: Electricity Bill Calculator
Energy and Cost
Working
- 1,500 W × 8 h ÷ 1,000 = 12 kWh a day
- × 30 days = 360 kWh a month
- × ₹8 = ₹2,880 a month
Step 2: from units to rupees
Most Indian states charge on a telescopic slab tariff: the first units are cheap and each further block costs more. Each slab's rate applies only to the units inside it. Using an example tariff of ₹4 for the first 100 units, ₹6 for 101–200 and ₹8 above that, 379 units cost:
| Units | Units in slab | Rate | Amount |
|---|---|---|---|
| 1–100 | 100 | ₹4 | ₹400 |
| 101–200 | 100 | ₹6 | ₹600 |
| Above 200 | 179 | ₹8 | ₹1,432 |
| Energy charges | ₹2,432 | ||
| Fixed charge | ₹100 | ||
| Electricity duty (5%, example) | ₹122 | ||
| Bill | ₹2,654 |
Notice the effect of slabs: the AC's 216 units fall in the most expensive slab, so cutting AC use saves at the top rate.
Other lines on the bill
- Fixed or demand charge: a monthly amount based on your sanctioned load (kW), paid even if you use nothing.
- Fuel or power purchase adjustment: a per-unit surcharge that changes with the utility's fuel costs.
- Electricity duty: a state tax, usually a percentage of energy charges.
- Subsidy: several states give free or cheaper units up to a limit for households.
Choosing a new AC? Read what size AC you need.
Frequently asked questions
How many units does a 1.5 ton AC use?
About 1 to 1.5 units an hour at full power for an inverter model. Six hours a day is roughly 200 units a month.
How many units does a fan use?
A 70 W ceiling fan uses 0.07 units an hour, about 21 units a month at 10 hours a day. A BLDC fan uses less than half that.
What is a telescopic tariff?
A slab tariff where each rate applies only to the units in that slab, so using more raises the cost of the extra units, not all of them.
Why is my bill high even with low usage?
Fixed charges, fuel adjustment surcharges and duty are added on top of energy charges. Check the sanctioned load too: a higher load means a higher fixed charge.
Sources
- Bureau of Energy Efficiency: appliance star labels and energy use
- State Electricity Regulatory Commissions: retail tariff orders (slabs, fixed charges and duty)
Last reviewed: 10 October 2026