Electricity Cost Calculator
Estimate energy usage and cost for any appliance in seconds.
How this kilowatt hour cost calculator works
A kilowatt hour (kWh) is the unit your utility company uses to bill electricity usage. This calculator converts your appliance power rating and usage habits into total energy consumption, then multiplies that by your local utility rate.
The core formula is simple: Energy (kWh) = Watts × Hours ÷ 1000. After you know the kWh used, cost is: Cost = kWh × Electricity Rate.
What each input means
- Appliance Power (Watts): The device's power draw. Usually printed on a label.
- Hours Used Per Day: Average daily runtime for that appliance.
- Electricity Rate: Your price per kWh from your utility bill.
- Number of Days: Billing period (for example, 30 days).
- Number of Devices: Useful when you have multiple identical units.
Quick examples
Example 1: Space heater
A 1500W space heater running 4 hours per day at $0.18/kWh:
- Daily energy: (1500 × 4) ÷ 1000 = 6 kWh
- Daily cost: 6 × 0.18 = $1.08
- 30-day cost: $32.40
Example 2: LED light bulb
A 10W bulb running 6 hours per day at $0.15/kWh:
- Daily energy: (10 × 6) ÷ 1000 = 0.06 kWh
- Daily cost: 0.06 × 0.15 = $0.009
- 30-day cost: about $0.27
Why this matters for your electric bill
Many people underestimate how much high-wattage appliances add to monthly utility costs. Heating devices, dryers, ovens, water heaters, and air conditioners can dominate your bill. Even small habit changes can create noticeable savings over a year.
Tips to reduce electricity costs
- Replace old bulbs with LEDs.
- Use smart plugs or timers to avoid phantom usage.
- Run full loads in dishwashers and laundry machines.
- Set HVAC thermostats for efficiency, not extremes.
- Compare appliance energy ratings before buying new equipment.
Frequently asked questions
Is watts the same as kilowatt hours?
No. Watts are a measure of power at a moment in time. Kilowatt hours are a measure of energy used over time.
Where do I find my electricity rate?
Check your utility bill. Look for “price per kWh,” “energy charge,” or “supply rate.” If there are multiple tiers, use the one that best matches your typical usage.
Can I calculate yearly cost?
Yes. This calculator also estimates daily, monthly (30-day), and yearly (365-day) cost to help with budgeting and appliance comparisons.