电费计算器
Calculate how much an appliance costs to run
Calculate exactly how much any appliance, device, or system costs to run per hour, day, month, or year. Enter the wattage, hours of use, and your electricity rate to see the cost instantly. Compare appliances, estimate your electric bill, and find the biggest energy hogs in your home.
A 1,000-watt space heater running 8 hours a day at the US average rate of $0.16/kWh costs $1.28/day, $38.40/month, and $467.20/year. Formula: (Watts × Hours ÷ 1,000) × Rate = Cost.
| Appliance | Watts | Monthly* |
|---|---|---|
| LED Light Bulb | 10W | $0.38 |
| Laptop | 65W | $2.50 |
| Desktop PC | 300W | $11.52 |
| TV (55") | 100W | $3.84 |
| Refrigerator | 150W | $5.76 |
| Washing Machine | 500W | $19.20 |
| Dryer | 3000W | $115.20 |
| Space Heater | 1500W | $57.60 |
How to Calculate Electricity Cost
How to Use This Calculator
- Enter the wattage — Find the wattage on the appliance label, in the manual, or on the manufacturer's website. Common examples: light bulb (60W), laptop (50W), space heater (1,500W), refrigerator (150W average).
- Enter hours of use per day — Estimate how many hours the device runs daily. A refrigerator runs ~8 hours of active compressor time per day. A TV might run 4–6 hours.
- Enter your electricity rate — Find this on your utility bill, listed as $/kWh (dollars per kilowatt-hour). The US national average in 2026 is approximately $0.16/kWh, but rates vary widely by state.
- Read the results — See the cost per hour, per day, per month, and per year, plus total kWh consumed.
Example: A 60W LED-equivalent light bulb (actually 9W LED) running 10 hours/day at $0.16/kWh: (9 × 10 / 1,000) × $0.16 = $0.014/day = $0.44/month.
The Formula Explained
The electricity cost formula has three components:
Daily Cost = (Watts × Hours per Day ÷ 1,000) × Electricity Rate ($/kWh)
Dividing by 1,000 converts watts to kilowatts, since electricity is billed in kilowatt-hours (kWh). One kWh = running a 1,000-watt device for 1 hour.
Worked example: A window AC unit rated at 1,200 watts runs 10 hours per day. Your rate is $0.18/kWh.
- Daily kWh = 1,200 × 10 / 1,000 = 12 kWh
- Daily cost = 12 × $0.18 = $2.16/day
- Monthly cost = $2.16 × 30 = $64.80/month
- Annual cost = $2.16 × 365 = $788.40/year
Common Scenarios — Pre-Calculated Reference
Common Appliance Running Costs (at $0.16/kWh)
| Appliance | Typical Wattage | Daily Hours | Monthly Cost | Annual Cost |
|---|---|---|---|---|
| LED light bulb (60W equivalent) | 9 W | 8 | $0.35 | $4.21 |
| Incandescent light bulb | 60 W | 8 | $2.30 | $28.03 |
| Laptop computer | 50 W | 8 | $1.92 | $23.36 |
| Desktop computer + monitor | 300 W | 8 | $11.52 | $140.16 |
| LED TV (55") | 80 W | 5 | $1.92 | $23.36 |
| Refrigerator | 150 W (avg) | 8 (compressor) | $5.76 | $70.08 |
| Window AC unit | 1,200 W | 8 | $46.08 | $560.64 |
| Central AC (3-ton) | 3,500 W | 8 | $134.40 | $1,635.20 |
| Space heater | 1,500 W | 8 | $57.60 | $700.80 |
| Electric water heater | 4,500 W | 3 | $64.80 | $788.40 |
| Clothes dryer | 5,000 W | 1 | $24.00 | $292.00 |
| Washing machine | 500 W | 1 | $2.40 | $29.20 |
| Dishwasher | 1,800 W | 1 | $8.64 | $105.12 |
| Electric oven | 2,500 W | 1 | $12.00 | $146.00 |
| Hair dryer | 1,875 W | 0.25 | $2.25 | $27.39 |
| Phone charger | 5 W | 3 | $0.07 | $0.88 |
| WiFi router | 12 W | 24 | $1.38 | $16.82 |
| Gaming PC | 500 W | 4 | $9.60 | $116.80 |
| Pool pump | 1,500 W | 8 | $57.60 | $700.80 |
| EV charger (Level 2) | 7,200 W | 4 | $138.24 | $1,681.92 |
Average Electricity Rates by State (2026 Estimates, $/kWh)
| State | Rate | State | Rate |
|---|---|---|---|
| Hawaii | $0.43 | Texas | $0.14 |
| Connecticut | $0.29 | Florida | $0.15 |
| Massachusetts | $0.28 | Ohio | $0.13 |
| California | $0.27 | Illinois | $0.14 |
| New York | $0.24 | Washington | $0.11 |
| New Jersey | $0.20 | Idaho | $0.10 |
| US Average | $0.16 | Louisiana | $0.11 |
Pro Tips
- Use a Kill A Watt meter for accurate readings. Plug-in power meters ($20–$30) measure actual wattage, which can differ significantly from the label. Refrigerators cycle on and off, so measure over 24 hours for an accurate average.
- LED bulbs save $100+ per bulb over their lifetime. Replacing a 60W incandescent with a 9W LED saves 51W. Over 25,000 hours of bulb life at $0.16/kWh, that is $204 in electricity savings from a $2 bulb.
- Standby power ("phantom load") adds up. Devices like TVs, game consoles, and chargers draw 1–15W even when "off." A home with 20 devices averaging 5W standby draws 100W continuously = 876 kWh/year = $140/year wasted.
- Time-of-use rates can cut costs 30–50%. Many utilities offer lower rates during off-peak hours (typically 9 PM–7 AM). Run dishwashers, laundry, and EV chargers overnight to pay the lowest rate.
- Your AC is almost certainly your biggest expense. Central AC can consume 3,000–5,000W. Raising your thermostat by just 2°F can reduce cooling costs by 5–10%.
- Compare annual costs when appliance shopping. The EnergyGuide yellow label on appliances shows estimated annual operating cost. A $500 fridge that costs $50/year to run is cheaper over 10 years than a $400 fridge that costs $75/year.
- Solar payback calculation. If your annual electricity cost is $2,000 and a solar system costs $15,000 after incentives, the payback period is roughly 7.5 years. Use this calculator to estimate your current annual cost first.
Real-World Applications
- Budgeting and bill estimation: Add up the monthly costs of all your major appliances to estimate your electricity bill before it arrives. This helps identify months when costs will spike (summer AC, winter heating).
- Appliance comparison shopping: An energy-efficient refrigerator might cost $100 more upfront but save $25/year in electricity. Over a 15-year lifespan, that is $375 in savings — a clear win.
- Cryptocurrency mining profitability: A mining rig drawing 1,200W 24/7 costs $1,382/year at $0.16/kWh. If it mines $1,000/year in crypto, it operates at a $382/year loss on electricity alone.
- EV charging costs: A Tesla Model 3 with a 60 kWh battery charging from 20% to 80% needs 36 kWh. At $0.16/kWh, that is $5.76 per charge — roughly equivalent to driving 200 miles for under $6.
- Landlord/tenant billing: When electricity is included in rent, landlords use these calculations to estimate utility allowances. A space heater in every room can add $200+/month to electricity costs.
- Off-grid and solar sizing: To size a solar+battery system, first calculate your total daily kWh consumption. A home using 30 kWh/day needs at least a 7.5 kW solar array (assuming 4 peak sun hours).
Common Mistakes to Avoid
- Using the maximum wattage for variable-load appliances. A refrigerator is rated at 600W but only draws that when the compressor kicks on. Average consumption is 100–200W. Use a power meter to get the actual average.
- Forgetting about 240V appliances. Electric dryers, water heaters, ovens, and EV chargers use 240V circuits and draw much more power than 120V devices. A 240V/30A circuit can deliver 7,200W.
- Ignoring demand charges (commercial customers). Businesses often pay both per-kWh and per-peak-kW charges. Running all heavy equipment simultaneously creates a demand spike that increases the bill even if total kWh is the same.
- Not accounting for seasonal variation. AC usage in summer and heating in winter create dramatic swings. A $100/month spring bill can become $300+ in August. Average your annual cost for realistic budgeting.
- Assuming all kWh cost the same. Tiered rate structures charge more as usage increases. The first 500 kWh might cost $0.12/kWh, but usage above 1,000 kWh might cost $0.22/kWh. Check your utility's rate tiers.
Sources
- U.S. Energy Information Administration (EIA) — Average retail electricity prices by state, 2026
- ENERGY STAR — Appliance wattage estimates and annual energy consumption data
- Department of Energy (DOE) — Estimating Appliance and Home Electronic Energy Use
- Lawrence Berkeley National Laboratory — Standby power consumption database
Related Calculators
- Unit Converter — Convert between watts, kilowatts, BTU, and other energy units
- Percentage Calculator — Calculate percentage savings from efficiency upgrades
- Percentage Change Calculator — Compare electricity bills month to month
- ROI Calculator — Calculate return on investment for solar panels and energy upgrades
- Break-Even Calculator — Find when an energy-efficient appliance pays for itself
常见问题
Multiply the wattage by hours of use to get watt-hours, divide by 1,000 to convert to kilowatt-hours (kWh), then multiply by your electricity rate. Formula: Cost = (Watts x Hours x Days) / 1000 x Rate Per kWh. Example: A 1,500W heater running 8 hours at $0.16/kWh costs (1500 x 8) / 1000 x 0.16 = $1.92 per day.
The national average residential electricity rate in 2026 is approximately $0.16 per kWh. Rates vary significantly by state: Hawaii is highest at about $0.43/kWh, while Washington state is lowest at about $0.11/kWh. Check your utility bill for your exact rate — it may include tiered pricing where the rate increases with usage.
A typical 1,500-watt space heater running 24 hours at the national average rate of $0.16/kWh costs $5.76 per day, $172.80 per month, or $2,102.40 per year. Running it only 8 hours per day costs $1.92/day or $57.60/month. This makes space heaters one of the most expensive appliances to operate.
The biggest electricity consumers are: HVAC (heating/cooling) at 40-50% of the bill, water heater at 12-15%, washer/dryer at 8-10%, lighting at 8-10%, and refrigerator at 5-8%. A central AC unit uses about 3,500W, an electric water heater 4,500W, and a clothes dryer 3,000W. Reducing HVAC usage has the biggest impact.
The average U.S. household uses approximately 886 kWh per month (about 29.5 kWh per day), according to EIA data. This translates to an average monthly bill of about $142 at $0.16/kWh. Usage varies by region — southern states use more for cooling, northern states use more for heating.
A kilowatt-hour is a unit of energy equal to using 1,000 watts for one hour. It is how utility companies measure and bill electricity usage. For example, a 100-watt light bulb running for 10 hours uses 1 kWh (100W x 10 hours = 1,000 Wh = 1 kWh). At $0.16/kWh, that costs $0.16.
Yes, most electronics draw "phantom" or "standby" power when plugged in but not actively in use. A typical home wastes 5-10% of electricity on phantom loads, costing $100-$200 per year. Worst offenders include cable boxes (15-30W), game consoles (5-25W), and phone chargers (0.2-5W). Use smart power strips to eliminate phantom loads.
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