How this calculation works
Start with the kWh used during one billing period, either from your bill or from the difference between two meter readings. Under slab pricing, successive portions of that usage can have different prices. A flat tariff uses one price throughout. Add the fixed charge and other applicable amounts to estimate the total, checking the tax basis separately. Official utility billing guidance describes energy charges, fixed charges and adjustments as distinct bill components; their exact treatment depends on your tariff. Use your own applicable rates in this calculator.
Worked example
This example uses illustrative inputs. Your current result is shown above.
The example uses 250 units over 30 days: the first 100 at ₹3 cost ₹300, the next 100 at ₹5 cost ₹500, and the remaining 50 at ₹7 cost ₹350. Energy and the total bill are ₹1,150 with extras off. If you add a ₹100 fixed charge, a ₹0.50/unit surcharge (₹125), 5% tax on energy only (₹57.50), ₹20 other charges and a ₹50 discount, the bill becomes ₹1,402.50. These rates are arithmetic examples, not a provider tariff.
Assumptions and limits
- All rates and amounts are editable examples or user inputs. No state, DISCOM or provider tariff is selected or fetched automatically.
- Usage and slab widths apply to the entire entered billing period. Billing days change daily averages only; monthly slab widths, fixed charges and other amounts are never prorated automatically.
- Slabs are successive blocks: widths of 100 and 100 mean the first 100 units and the next 100 units. Each unit is charged once at the rate of its block. Up to 10 blocks are allowed, with an unlimited final block.
- Meter readings are cumulative kWh from the same meter, with no multiplier. A smaller current reading, meter rollover or meter replacement must be resolved before entering readings; use known consumption directly when appropriate.
- When extras are enabled, the fixed charge and other charges are added once. The surcharge is a rupee amount per unit, not a percentage surcharge.
- Tax applies only to the selected basis: energy alone, or energy plus the fixed charge and per-unit surcharge. Other charges are excluded from tax. Discount is deducted after tax and cannot exceed the pre-discount bill.
- This estimate does not automatically apply minimum bills, demand charges, time-of-day rates, net-metering credits, subsidy eligibility or tariff changes within a period. Provider rounding and billing rules can also change the actual bill.
- Zero usage is allowed. Fixed or other charges can still create a bill; an effective cost per unit is undefined when no units are used.
Questions people ask
What is one unit of electricity?
One unit means one kilowatt-hour (kWh): the energy used by a 1 kW load running for one hour. For example, a 100 W device running for 10 hours uses 1 kWh. Kilowatts describe power; kilowatt-hours describe energy used over time.
Are these the current rates for my electricity provider?
No. The starting rates are editable examples. Find the rates, charge amounts and tax basis for your connection category and billing period in your provider’s tariff schedule or bill. This calculator does not select a state, verify a tariff or determine subsidy eligibility.
Should I enter slab limits or the number of units in each slab?
Enter the number of units in each successive slab. For a schedule covering 0–100, 101–200 and above 200 units, enter 100, then another 100, then all remaining units. At 250 units, those slabs contain 100, 100 and 50 units. This is progressive slab pricing; it does not apply the highest reached rate to all usage.
Does a 60-day bill automatically double monthly slabs?
No. Billing days are used only to calculate daily averages. Enter slab widths and all charge amounts that already apply to the full billing period. If your provider adjusts monthly slabs by reading dates, calculate those allowed widths under its rules before entering them here.
How do I calculate units from meter readings?
Subtract the previous cumulative kWh reading from the current reading on the same meter. Readings of 1,000 and 1,250 give 250 units. This assumes a meter multiplier of one and no reset or rollover. If your bill uses a multiplier or adjusted readings, enter the verified units directly instead.
Which charges are taxed, and when is the discount applied?
Choose either the energy charge alone or energy plus the fixed charge and surcharge as the tax basis. Other charges are added after tax and are always excluded from that basis. Discount or credit is deducted last. These are calculator options, not a statement of the tax rules for any provider.
Why might my actual bill be different?
Your provider may use minimum or demand charges, time-of-day prices, percentage-based adjustments, net metering, subsidy rules, arrears, different rounding, or rates that change within the billing period. The calculator applies only the flat or progressive slab rates and extra amounts you enter.
Why is the effective cost per unit higher than a slab rate?
The effective cost per unit divides the whole estimated bill, after extras and discount, by total usage. Fixed charges and tax can make it higher than an energy rate. At zero usage there is no meaningful per-unit average, even if fixed charges leave an amount to pay.