Energy Use Calculator
Estimate electricity consumption and cost.
Formula
- Use the units shown beside each field.
- Results update automatically whenever you change an input.
- Displayed values use up to four decimal places, or scientific notation for very small or large numbers. Calculations retain full precision.
Example Calculation
- Appliance power: 1000 W
- Use per day: 3 hours
- Days: 30
- Electricity price: 0.2 $/kWh
A 1,000 W appliance used 3 hours daily for 30 days consumes 90 kWh.
Frequently asked questions
How do I use this calculator?
Enter appliance power, use per day, days, electricity price. The result updates automatically. Use Reset to restore the example values.
What method does it use?
Energy = watts / 1000 × hours × days. Follow the units and definitions shown with the inputs to apply this relationship consistently.
Why might a rounded result differ?
The calculation keeps full numeric precision internally, then rounds the displayed result. Rounding intermediate steps by hand can produce a slightly different answer.
Are my inputs saved online?
No. This calculator processes your inputs in your browser. A recently used list stores only calculator names on this device, not your entered values.
Check the assumptions and units before using this result. Read about calculation methods.