Calculator Inputs
Example Data Table
| Appliance | Power (W) | Qty | Hours/Day | Days/Month | Rate ($/kWh) | Estimated Energy (kWh) | Estimated Energy Cost ($) |
|---|---|---|---|---|---|---|---|
| Air Conditioner | 1500 | 1 | 8 | 30 | 0.18 | 360.00 | 64.80 |
| Refrigerator | 180 | 1 | 24 | 30 | 0.18 | 129.60 | 23.33 |
| LED Television | 120 | 1 | 5 | 30 | 0.18 | 18.00 | 3.24 |
| Desktop Computer | 250 | 2 | 6 | 30 | 0.18 | 90.00 | 16.20 |
These examples show energy-only estimates. Final bills can increase after fixed charges, meter rent, adjustments, taxes, and standby consumption are included.
Formula Used
1) Active energy usage:
Monthly kWh = (Power in watts × Daily usage hours × Quantity × Billing days) ÷ 1000
2) Time-of-use energy usage:
Peak kWh = (Power × Peak hours × Quantity × Billing days) ÷ 1000
Off-peak kWh = (Power × Off-peak hours × Quantity × Billing days) ÷ 1000
3) Standby energy:
Standby kWh = (Standby watts × Standby hours × Quantity × Billing days) ÷ 1000
4) Energy charges:
Energy cost = Active energy cost + Standby cost
5) Bill subtotal:
Subtotal = Energy charges + Fixed charge + Meter rent + Fuel adjustment
6) Rebate and tax:
Rebate amount = Subtotal × Rebate %
Taxable base = Subtotal − Rebate amount
Tax amount = Taxable base × Tax %
7) Final monthly bill:
Total monthly cost = Taxable base + Tax amount
How to Use This Calculator
- Enter the appliance name for easier recordkeeping.
- Select either flat-rate billing or time-of-use billing.
- Input rated power, standby power, quantity, and billing days.
- For flat-rate mode, enter total daily usage hours and the standard rate.
- For time-of-use mode, enter peak and off-peak hours with matching tariffs.
- Add fixed charges, meter rent, fuel adjustment, tax, and any rebate.
- Optionally enter an emission factor to estimate monthly carbon output.
- Click the calculate button to view results above the form.
- Use the CSV or PDF buttons to save the current estimate.
Frequently Asked Questions
1. What does this calculator estimate?
It estimates monthly electricity cost using wattage, daily use, quantity, billing days, tariffs, standby consumption, fixed charges, taxes, and optional rebates. It also shows energy usage, cost per kWh, annual projection, and estimated emissions.
2. When should I use flat-rate mode?
Use flat-rate mode when your electricity provider charges the same price for each kilowatt-hour all day. You only need one tariff and your average daily operating hours.
3. When should I use time-of-use mode?
Use time-of-use mode when peak and off-peak electricity rates differ. Enter separate operating hours and tariffs so the estimate matches your bill structure more closely.
4. Why include standby power?
Many devices draw electricity even when not actively used. Including standby watts improves accuracy for routers, televisions, gaming consoles, chargers, and similar equipment that stay plugged in continuously.
5. Does this calculator replace my utility bill?
No. It is an estimate tool. Actual bills can vary because of tariff slabs, minimum charges, utility surcharges, seasonal fees, and taxes that differ by provider or region.
6. How can I reduce monthly electricity cost?
Reduce power use, shorten operating hours, switch to efficient appliances, cut standby losses, and shift flexible usage away from peak periods when your utility uses time-based tariffs.
7. What unit is used for billing?
Electricity is usually billed in kilowatt-hours. One kilowatt-hour means using 1000 watts of power for one hour. This calculator converts watt input into monthly kilowatt-hour consumption.
8. Can I use this for several appliances?
Yes. Calculate each appliance separately, then add the monthly totals. This gives better visibility into which devices contribute most to your overall electricity cost.