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How to use
- Enter Old lamp watts.
- Enter LED watts.
- Enter Number of bulbs.
- Enter Hours per day.
- Enter Days.
- Enter Price per kWh.
- Calculate, then review power, price and period before comparing.
How it is calculated
Saved kWh = watt difference × count ÷1000 × hours × days
Example
Replacing twenty 60 W lamps with 10 W LEDs for 6 hours daily saves 2,190 kWh annually and about 394.2 at 0.18 per kWh.
Important notes
This calculator compares energy only. Lamp purchase price, lifetime and maintenance determine the actual investment payback.
Worked examples and interpreting results
| Case | Calculation | Result |
|---|---|---|
| Energy saved | (60 − 10) × 20 ÷ 1000 × 6 × 365 | 2,190 |
| Savings | 2190 × 0.18 | 394.2 |
Frequently asked questions
What if the LED wattage is higher than the old lamp?
Savings become negative mathematically, indicating higher energy use instead of savings.
Is the result an actual utility bill?
No. It is a calculation from your usage, price and inputs; real tariffs, taxes and fixed fees may add other items.
How can I improve accuracy?
Use measured or device-specific power and usage plus the actual electricity price for the same period.