When to use this calculator
Estimate electricity consumption from appliance power and operating hours. Assumes the appliance draws the entered power throughout its running time.
Explore the electricity use & bills calculators for other questions in this topic. For a related calculation, use the Area Normalised Insulation R Value Calculator: Find thermal resistance per unit area from insulation thickness and conductivity.
PUTTING IT INTO PRACTICE
Appliance Energy: 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 |
|---|---|
| Power (W) | 1,000 |
| Hours per day | 2 |
| Days (integer) | 30 |
| Result | 60 kWh |
- Check the input labels and enter the example values above.
- Apply the relationship: Energy (kWh) = watts ÷ 1000 × hours/day × days.
- The result is 60 kWh, rounded for display.
How to interpret your result
Assumes the appliance draws the entered power throughout its running time.
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 appliance energy calculator?
Enter power (w), hours per day, 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?
Energy (kWh) = watts ÷ 1000 × hours/day × days.
What should I check before using the result?
Assumes the appliance draws the entered power throughout its running time.
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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