Electricity Cost Calculator (kWh)
Enter your appliance usage details to estimate electricity cost per hour, day, month, and year.
Tip: If your utility bill shows cents per kWh, convert to dollars (for example, 18.5¢ = 0.185).
How this kilowatt per hour cost calculator works
This calculator helps you estimate how much an appliance costs to run based on power draw, usage time, and your local electricity rate. Most people search for a “kilowatt per hour cost calculator,” but electric bills are actually based on kilowatt-hours (kWh). A kilowatt-hour is a unit of energy: using 1,000 watts for one hour equals 1 kWh.
With a few inputs, you can quickly see cost per hour, daily cost, monthly cost, and yearly cost. This is useful when comparing appliances, deciding whether to replace old equipment, or trying to lower your utility bill.
The formula behind the calculation
Step-by-step formula
- kW = Watts ÷ 1,000
- Cost per hour = kW × Electricity rate × Quantity
- Daily kWh = kW × Hours per day × Quantity
- Monthly kWh = Daily kWh × Days per month
- Cost = Energy (kWh) × Rate ($/kWh)
The calculator also estimates annual cost using a 365-day year to give you a long-term view of spending.
Example: space heater operating cost
Suppose you run a 1,500W space heater for 4 hours per day at a utility rate of $0.18 per kWh:
- 1,500W = 1.5kW
- Per hour cost = 1.5 × 0.18 = $0.27
- Daily energy = 1.5 × 4 = 6 kWh
- Daily cost = 6 × 0.18 = $1.08
- Monthly cost (30 days) = $32.40
That one appliance can add a noticeable amount to your electric bill, especially in colder months.
Common appliance wattage ranges
Use these typical ranges if you do not know exact wattage:
- LED bulb: 8–15W
- Laptop: 45–100W
- Desktop PC + monitor: 200–500W
- Refrigerator: 100–800W (cycles on/off)
- Microwave: 700–1,200W
- Window AC unit: 500–1,500W
- Electric water heater: 3,000–4,500W
- Clothes dryer: 2,000–5,000W
For the most accurate estimate, check the appliance label or user manual and use your utility provider’s current kWh rate.
How to reduce electricity costs
1) Cut runtime first
Reducing hours of use often saves more than chasing tiny efficiency gains. Timers, smart plugs, and schedules are simple, effective tools.
2) Replace high-wattage devices
Prioritize old refrigerators, electric resistance heaters, and inefficient lighting. New ENERGY STAR products can reduce energy usage significantly.
3) Shift usage when rates are lower
If your plan includes time-of-use pricing, run dishwashers, laundry, or EV charging during off-peak windows whenever possible.
4) Track your largest loads monthly
Checking just 3–5 big appliances every month keeps your bill predictable and helps identify unexpected spikes early.
Frequently asked questions
Is “kilowatt per hour” the right term?
In everyday speech, people say “kilowatt per hour,” but utility billing uses kilowatt-hour (kWh). This page calculates the billed unit.
Why is my bill higher than the calculator estimate?
Real bills can include delivery charges, fixed fees, taxes, demand charges, and varying rates throughout the month. The calculator estimates energy-only cost.
Can I use this for solar or battery planning?
Yes. Monthly and annual kWh estimates are a good starting point for sizing solar production or battery storage needs.
Bottom line
A good electricity bill estimator gives you control. Use this kWh calculator to test different usage patterns, compare appliances, and find the biggest opportunities to save. Small daily decisions can compound into meaningful yearly savings.