Electricity Bill Calculator
Estimate monthly electricity units (kWh) and your electricity bill from appliance wattage, entered units or meter readings. Compare flat vs progressive slab tariffs, include fixed charges and duty, and see a clear breakdown of energy use and costs.
Calculate electricity use and cost
Add one or more appliances and enter power, hours per day and quantity to estimate billing-period units.
Appliances used
Wattage and hours are estimates. Add up to 20 appliance groups.
Preset wattages and operating hours are rough examples, not measured values. Use the electrical input rating and realistic operating hours for your device; cycling appliances like fridges and ACs vary.
Subtract cumulative readings for the same register and meter multiplier. If your bill uses a multiplier or separate registers, convert to actual billed kWh first and use the Units mode.
Electricity tariff & extra charges
Enter rates from your bill. Every prefilled rate is illustrative.
This is a progressive tariff: each block is charged at its own rate. Some utilities use different slab rules, bi-monthly blocks or additional adjustments. Replace example values with your bill's applicable rates.
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Appliance-wise electricity consumption
Compare contributions to overall estimated energy use; the tariff is applied to the total, not separately to each appliance.
| Appliance | Quantity | Daily kWh | Period kWh | Share |
|---|
Progressive slab cost breakdown
Each group of units is charged only at that group's price.
| Usage range | Units billed | Rate per unit | Charge |
|---|
Electricity bill formula: Energy used (kWh) = power (watts) × daily hours × billing days × quantity ÷ 1,000. With a flat rate, energy cost = kWh × cost per unit. In this tool, estimated bill = energy charges + fixed charges + entered duty percentage × energy charges.
What is an electricity bill calculator?
An electricity bill calculator estimates how much energy is consumed during a billing period and how much the usage might cost. Electricity companies commonly measure energy in kilowatt-hours (kWh), also called electricity units in India. The total payable bill may include unit-based charges plus additional fixed, tax and adjustment components.
CalcuPortal lets you calculate units from multiple appliances, enter known units directly, or subtract previous and current meter readings. You can then apply a single flat price per kWh or an editable progressive slab tariff and add optional fixed fees and duty.
How to calculate electricity units from watts
Daily energy
Daily kWh = Watts × Hours × Quantity ÷ 1,000
Billing-period energy
Period kWh = Daily kWh × Billing days
Flat-rate bill
Cost = Period kWh × Rate per kWh, before extras.
For example, a 1,000 W appliance running five hours each day uses 5 kWh daily. Over 30 days, it uses 150 kWh. At an illustrative rate of ₹8 per kWh, energy cost is ₹1,200 before fixed charges and duty. A US Department of Energy educational module explains this watts-times-hours method in its energy-efficiency learning resource.
How to use this electricity bill calculator
- Choose By appliances, By monthly units, or By meter readings.
- For appliances, add each appliance's electrical input wattage, quantity and estimated hours of use per day. For other modes, enter units or matching cumulative meter readings.
- Set the number of days in the billing period, for example 30 days or your actual bill's cycle.
- Choose your currency and enter your utility's flat rate or editable progressive slab rates.
- Add any fixed fee and a percentage duty on energy charges if applicable.
- Click Calculate bill to review total units, estimated payable amount, cost breakdown and appliance or tariff details.
Calculate an electricity bill from meter readings
For a standard cumulative meter measuring kilowatt-hours, subtract the previous reading from the current reading to find units used. If the previous reading was 12,500 kWh and the current reading is 12,750 kWh, consumption is 250 kWh for the period. Enter those values under the Meter readings tab.
Check your actual bill before using the simple subtraction. Some accounts have separate registers for time-of-day consumption, multipliers or adjustments. If the utility bills kVAh or uses a metering multiplier, calculate the appropriately adjusted units using your billing documents before entering a number.
Flat tariff vs progressive electricity slabs
A flat-rate estimate multiplies all kWh by one price. A progressive slab system instead charges the first block of units at the first rate, the next block at a second rate and further units at another rate. Earlier units retain their original rate when the total crosses a new threshold.
For example, a sample tariff with 0–100 units at ₹5, the next 100 at ₹7, and usage above 200 at ₹9 yields ₹1,650 in energy charges for 250 kWh. This is an illustration, not a current tariff for any state or electricity company.
| Example slab | Billed units | Rate | Charge |
|---|---|---|---|
| First 100 kWh | 100 | ₹5/kWh | ₹500 |
| Next 100 kWh | 100 | ₹7/kWh | ₹700 |
| Above 200 kWh | 50 | ₹9/kWh | ₹450 |
| Total | 250 | — | ₹1,650 |
Important: not all tariffs use progressive blocks. Some apply a single rate based on the final usage band, separate fixed charges or bi-monthly slabs. This tool implements only the explicitly described progressive method; check your electricity board's rules.
How electricity bills are calculated in India
In India, electricity rates can depend on the state, distribution company (DISCOM), consumer category, sanctioned load and billing period. Charges may include energy units, fixed or demand charges, adjustments, electricity duty and applicable subsidies. Regulatory authorities determine tariffs, and these schedules can change over time.
To find authoritative current rates, refer to your utility's most recent bill and applicable regulatory order. The Central Electricity Authority (CEA) publishes electricity tariff reference reports, and your State Electricity Regulatory Commission or DISCOM publishes the tariff schedule relevant to your connection. This page does not claim to fetch live BESCOM, TNEB, MSEDCL or any other utility rate.
Example appliance electricity consumption chart
The table shows illustrative electricity consumption for typical appliance configurations. Actual energy use depends on operating mode, efficiency, thermostat cycling, power fluctuations and measured input wattage. The appliance presets in the calculator are editable estimates.
| Appliance example | Assumed power | Hours/day | kWh over 30 days |
|---|---|---|---|
| Ceiling fan | 75 W | 8 | 18 |
| LED bulb | 10 W | 5 | 1.5 |
| Air conditioner (average assumed draw) | 1,500 W | 6 | 270 |
| Laptop | 65 W | 6 | 11.7 |
| Refrigerator (illustrative effective operation) | 120 W | 10 | 36 |
Some appliances cycle on and off or change their consumption with load. Measuring energy with a compatible meter or using a reliable kWh rating can provide a closer estimate than applying nameplate wattage for every clock hour.
How to reduce electricity consumption
Check large appliances
Compare AC, water heating and other high-energy loads using realistic hours and power, rather than assuming every device has the same consumption.
Track actual meter units
Compare billed units month by month and investigate unusual changes in use, appliance condition or tariff components.
Review efficient alternatives
Compare rated or measured kWh for suitable alternatives and consider efficiency, duty cycle and total purchase cost.
Monthly versus yearly electricity estimates
The average daily energy use is the estimated billing-period kWh divided by the entered billing days. Projected annual energy uses that daily average multiplied by 365 days. The 12-period bill projection multiplies the current period's estimated bill by 12; it is a budgeting scenario, not a forecast for a different number of days.
Real annual charges may be different because billing-cycle length, rates, seasonal consumption, air-conditioner demand, taxes, subsidies and fixed fees can change. If your electricity bill is bi-monthly rather than monthly, the 12-period projection does not represent a calendar year.
Common electricity cost calculation mistakes
- Confusing watts with kilowatt-hours: W and kW measure power; kWh measures energy consumed over time.
- Ignoring number of devices: five identical bulbs consume more energy than one at the same wattage and hours.
- Using nameplate rating as constant draw: an AC or refrigerator may cycle, and actual demand can vary.
- Using one flat rate for a slab bill: progressive tariffs apply different rates to different blocks of usage.
- Leaving out fixed charges and duty: these can increase the final amount even if unit consumption is correct.
- Assuming sample rates are official: check the current tariff schedule, category, subsidies and billing-period rules.
Related electricity and energy tools
Frequently Asked Questions
How do I calculate electricity consumption in units?
Multiply appliance watts by hours per day, billing days and number of appliances; divide by 1,000. One unit is one kWh.
How much electricity does 1,000 W use over 5 hours?
It uses 5 kWh. Over 30 days that is 150 kWh; at an illustrative ₹8/unit the energy cost is ₹1,200 before additional fees.
How do I calculate an electricity bill from two meter readings?
For compatible cumulative kWh readings, subtract the previous value from the current value. Verify any meter multiplier, different register or bill adjustment first.
How is a slab electricity bill calculated?
Under progressive slabs, each portion of the units is multiplied by its corresponding per-unit rate. The tier charges are added together before applicable extras.
Does this tool automatically use India's current state-wise tariffs?
No. Prefilled rates are illustrative. Enter the applicable prices and charges from your official electricity bill or tariff order.
Why is my actual electricity bill different?
Your actual bill may have subsidies, demand and minimum charges, fuel adjustments, time-of-use rates, meter factors, arrears or tax rules not represented by the estimate.
What is the difference between kW and kWh?
kW measures power and kWh measures energy. An appliance using 1 kW for one hour consumes 1 kWh.
Last updated: October 18, 2026. This calculator is a budget estimate, not a live electricity tariff service or a statement of amounts due. All rates and duty values are supplied or edited by the user. Confirm billing data and applicable local regulations before relying on the result.