Electricity Bill Calculator
Estimate your monthly electricity bill from units consumed.
Flat-rate estimate; actual slab tariffs, duties and taxes vary by state DISCOM.
How the Electricity Bill Is Calculated
Your electricity bill is built from three parts: the energy charge for the units you consume, fixed charges levied regardless of usage, and taxes or duties. The core formula is simple:
Bill = (Units consumed × Rate per unit) + Fixed charges + Taxes
A unit is one kilowatt-hour (kWh): the energy used by a 1,000-watt appliance running for one hour. If your meter reads 9,420 last month and 9,720 this month, you consumed 300 units.
Suppose those 300 units are billed at an average rate of ₹6.50 per unit, with a fixed charge of ₹120 and a 5% electricity duty:
- Energy charge = 300 × ₹6.50 = ₹1,950
- Add fixed charge = ₹1,950 + ₹120 = ₹2,070
- Add 5% duty = ₹2,070 × 1.05 = ₹2,173.50
The calculator above does this arithmetic for you once you enter your units, rate and fixed charges.
Estimating Appliance Usage
If you do not yet have a meter reading, you can estimate consumption appliance by appliance. The units used by any device are:
Units (kWh) = (Wattage × Hours used per day × Days) ÷ 1000
For example, a 1.5-tonne air conditioner draws roughly 1,500 watts. Running it 8 hours a day for 30 days:
(1500 × 8 × 30) ÷ 1000 = 360 units in a month.
Typical wattage figures help you build a quick estimate:
- LED bulb: 9–12 W
- Ceiling fan: 70–80 W
- Refrigerator (avg.): 150–200 W running, but cycles on and off
- Television (LED): 80–120 W
- Geyser / water heater: 2,000–3,000 W
- Washing machine: 500–1,000 W
- Air conditioner (1.5 T): 1,400–1,800 W
Add up the monthly units for each appliance to get your household total, then multiply by your tariff to forecast the bill. This is also the fastest way to spot which appliances drive your costs — heating and cooling loads almost always dominate.
Slab Tariffs and State Variations
Most Indian electricity boards use a slab (telescopic) tariff, where the per-unit rate rises as you consume more. Each slab is charged at its own rate, not the whole bill at the top rate.
Consider an illustrative residential structure:
- 0–100 units: ₹4.00 per unit
- 101–300 units: ₹6.00 per unit
- Above 300 units: ₹7.50 per unit
For 350 units the energy charge would be:
- First 100 × ₹4.00 = ₹400
- Next 200 × ₹6.00 = ₹1,200
- Final 50 × ₹7.50 = ₹375
- Total energy charge = ₹1,975
The effective average rate is ₹1,975 ÷ 350 = ₹5.64 per unit, which you can plug into the calculator as your rate. Actual slabs, fixed charges and duties differ across states and between domestic, commercial and agricultural connections, and they are revised periodically by the state regulator. Always check the current tariff order from your discom for exact figures.
Frequently Asked Questions
One unit equals one kilowatt-hour (kWh), the energy consumed by a 1,000-watt appliance running for one hour. For example, ten 100-watt bulbs left on for one hour together use one unit.
Subtract last month's meter reading from this month's reading. The difference is the number of units you used during the billing period. Your bill also prints this figure under "units consumed".
Most states use slab tariffs, so consuming more units pushes part of your usage into higher-priced slabs. Seasonal loads like air conditioners or geysers raise consumption and therefore the average rate per unit.
Fixed charges are levied based on your sanctioned load or connection type, irrespective of how many units you use. They cover the cost of maintaining your connection and infrastructure, and are added on top of the energy charge.
Target high-wattage appliances first: use ceiling fans before air conditioners, set the AC to 24°C, switch to LED lighting and a higher star-rated refrigerator, and avoid running geysers longer than needed. Reducing units consumed also keeps you in lower-priced slabs.
Yes. Commercial, industrial and agricultural connections usually have different slab rates, fixed charges and sometimes demand charges compared with domestic connections. Enter the rate that matches your connection category for an accurate estimate.