Electrical calculator
Electrical Cost Calculator
Calculate the cost of running an electrical device.
About the electrical cost calculator
The electrical cost calculator estimates how much it costs to run an electrical device over time.
How to use this calculator
- 1
Enter device wattage
Enter the device's power consumption in watts.
- 2
Enter usage
Enter hours per day and number of days.
- 3
Enter electricity rate
Enter your rate per kWh (check your utility bill).
How the calculation works
Cost = (wattage × hours × days ÷ 1000) × rate. Shows daily, monthly, and yearly costs.
Example: 100W bulb, 8 hrs/day, $0.12/kWh, 30 days ≈ $2.88/month.
Safety first
These calculators provide estimates based on standard formulas and NEC guidelines. Always verify results with a licensed electrician before making installations. Electrical work can be dangerous — never work on live circuits, and always follow local building codes and regulations.
Understanding electrical units
Voltage (V) is electrical pressure, current (A) is flow rate, resistance (Ω) opposes flow, and power (W) is the rate of energy use. Ohm's law (V = I × R) relates the first three, while power formulas (P = VI, P = I²R) connect all four. Understanding these relationships is key to safe electrical design.
Important limitations
This tool provides a mathematical estimate based only on the values entered. It does not account for regulations, taxes, lender fees, market conditions, or individual circumstances. Results are for planning purposes only — consult a qualified professional for regulated, medical, financial, or construction decisions.
Frequently asked questions about electrical cost calculator
How accurate is the electrical cost calculator?+
The calculation follows the displayed formula and retains full numeric precision before formatting the result.
Can I use the result professionally?+
Use it as a planning estimate. Confirm regulated, medical, financial, or construction decisions with a qualified professional.