When to use this calculator
Estimate energy savings from replacing equal-use lighting with lower-wattage bulbs. Compare lamps with suitable light output. A negative result means increased consumption.
Explore the electricity use & bills calculators for other questions in this topic. For a related calculation, use the Standby Power Cost Calculator: Estimate annual electricity cost for a load left continuously in standby.
PUTTING IT INTO PRACTICE
LED Savings: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Old lamp power (W) | 60 |
| New lamp power (W) | 9 |
| Number of lamps (integer) | 10 |
| Daily operating hours | 5 |
| Days (integer) | 365 |
| Result | 930.75 kWh |
- Check the input labels and enter the example values above.
- Apply the relationship: Savings = (old W − new W) × lamps × hours × days ÷ 1000.
- The result is 930.75 kWh, rounded for display.
How to interpret your result
Compare lamps with suitable light output. A negative result means increased consumption.
Watts describe power and kilowatt-hours describe energy. Fixed charges do not vary directly with consumption. Devices with thermostats or cycling loads need measured average energy or realistic operating time.
Frequently asked questions
Can I multiply rated watts by 24 hours for every appliance?
Only if it actually draws that power continuously. Cycling and variable-power appliances require a better average-use estimate.
How do I use the led savings calculator?
Enter old lamp power (w), new lamp power (w), number of lamps (integer), daily operating hours, days (integer). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Savings = (old W − new W) × lamps × hours × days ÷ 1000.
What should I check before using the result?
Compare lamps with suitable light output. A negative result means increased consumption.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
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