Electricity Cost Calculator
Enter your appliance wattage, daily usage hours, and electricity rate — get instant daily, monthly, and yearly cost estimates. Use Simple mode for one device, or Multi mode for a full household inventory.
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Common Uses for an Electricity Cost Calculator
- ⚡ Find out how much your fridge, AC, or space heater costs per month
- 💡 Compare energy use of LED bulbs vs. old incandescent lights
- 🖥️ Estimate your home office electricity bill (PC, monitor, router)
- 🏠 Build a full household device inventory with standby power costs
- 📊 Decide if upgrading to an energy-efficient appliance pays off
- 🌙 Calculate savings from shifting usage to off-peak (day/night tariff)
How We Calculate Electricity Costs
Electricity is measured in kilowatt-hours (kWh). Here's how we calculate:
Energy consumption
- Daily consumption = (Power × Active hours + Standby × Standby hours) ÷ 1000
- Monthly consumption = Daily consumption × Days per month
Energy cost
- Single tariff: Cost = Consumption [kWh] × Price [$/kWh]
- Day/night tariff: Cost = (Day kWh × Day price) + (Night kWh × Night price)
Fixed fee and tax
- The fixed fee (service charge, distribution) is added as-is — we assume you enter the final amount from your bill.
- Tax is added only to energy cost, and only if you enable "Include tax" (when entering pre-tax prices).
Day/night tariff — important note
The "Night share" parameter is an estimate for your whole household. We assume the given percentage of your usage occurs during night hours and distribute it proportionally across all devices.
Examples
Refrigerator 150W for 24h/day, 30 days, price $0.15/kWh:
Consumption = 0.15 × 24 × 30 = 108 kWh/mo
Cost = 108 × 0.15 = $16.20/mo
Gaming PC 400W for 6h/day, 30 days, price $0.15/kWh:
Consumption = 0.4 × 6 × 30 = 72 kWh/mo
Cost = 72 × 0.15 = $10.80/mo
Air conditioner 1500W for 8h/day, 30 days, price $0.15/kWh:
Consumption = 1.5 × 8 × 30 = 360 kWh/mo
Cost = 360 × 0.15 = $54.00/mo
How to Calculate Electricity Cost from kWh
The core formula is simple: Cost = Power (W) ÷ 1000 × Hours × Price per kWh. The division by 1000 converts watts to kilowatts — your utility bill measures energy in kilowatt-hours (kWh), not watt-hours. For example, a 1,500W space heater running for 2 hours uses 3 kWh. At the US average rate of $0.16/kWh, that's $0.48 per session — or about $14/month if you run it 3 hours daily.
To find your monthly electric bill estimate, add up the monthly kWh for every major appliance and multiply the total by your electricity rate. Don't forget to include fixed charges (service fee, distribution) that appear on your bill regardless of usage — typically $10–20/month in the US.
Practical Examples
- Air conditioner (1,500W, 8h/day, 30 days): 1.5 × 8 × 30 = 360 kWh → $57.60/month at $0.16/kWh. Using a programmable thermostat and raising the set point by 2°C (4°F) can cut this by 10–15%.
- Space heater (1,500W, 3h/day, 30 days): 1.5 × 3 × 30 = 135 kWh → $21.60/month. Running two space heaters doubles the cost — central heating is usually cheaper for whole-home warmth.
- Gaming PC (400W, 6h/day, 30 days): 0.4 × 6 × 30 = 72 kWh → $11.52/month. Add a 27" monitor (50W) and the total rises to about $13/month — still less than most people expect.
For a solar comparison: if your household uses 900 kWh/month and pays $0.16/kWh, your annual electricity spend is ~$1,728. A 6 kW solar system producing 750 kWh/month would offset ~83% of that — use our Solar Panel ROI Calculator to estimate the payback period for your location.
Common Uses: Appliance Energy Costs at a Glance
Knowing the appliance energy cost for everyday devices helps you spot the biggest opportunities to reduce your bill. The table below uses $0.16/kWh — enter your own rate above for a precise figure.
| Appliance | Typical Power | Typical Daily Use | Monthly kWh | Monthly Cost* |
|---|---|---|---|---|
| Refrigerator | 150 W | 24 h | 108 kWh | $17.28 |
| Air Conditioner | 1,500 W | 8 h | 360 kWh | $57.60 |
| Space Heater | 1,500 W | 4 h | 180 kWh | $28.80 |
| Gaming PC | 400 W | 6 h | 72 kWh | $11.52 |
| Washing Machine | 500 W | 1 h (daily) | 15 kWh | $2.40 |
| Tumble Dryer | 3,000 W | 1 h (daily) | 90 kWh | $14.40 |
| Dishwasher | 1,200 W | 1 h (daily) | 36 kWh | $5.76 |
| LED TV (55") | 70 W | 5 h | 10.5 kWh | $1.68 |
| Laptop | 45 W | 8 h | 10.8 kWh | $1.73 |
| LED Bulb | 10 W | 5 h | 1.5 kWh | $0.24 |
| Phone Charger | 5 W | 2 h | 0.3 kWh | $0.05 |
| Standby (10 devices) | 30 W total | 20 h | 18 kWh | $2.88 |
*At $0.16/kWh — the 2024 US residential average. Source: U.S. EIA.
Key insight: The dryer and air conditioner are typically the two biggest discretionary energy loads. Switching from a gas dryer to a heat-pump dryer (800W) can cut drying costs by ~60%. Pairing your AC with a ceiling fan lets you raise the thermostat 2–3°C without loss of comfort.
Thinking about solar? Our Solar Panel ROI Calculator shows how quickly a rooftop system pays back based on your monthly usage. For heating costs, see the Heat Pump Calculator to compare heat pump vs. electric resistance heating.
FAQ
- What is a kWh (kilowatt-hour)?
- A kilowatt-hour is a unit of energy. 1 kWh = using 1000 watts for 1 hour. Your electricity bill is based on kWh consumed.
- Where do I find the wattage of my device?
- Check the label on the device (usually on the back or bottom), the manual, or the manufacturer's website. Examples: LED bulb 10W, laptop 50W, fridge 100-200W, space heater 1500-2000W, kettle 2000W.
- What is standby power and why does it matter?
- Standby power (vampire power) is energy consumed when a device is in sleep mode — indicator lights, clocks, WiFi modules. Individually it's 2-10W, but with 10+ devices over 20h daily, it adds $50-100 yearly.
- How do I estimate device usage hours?
- Fridge: 24h (runs continuously). TV: hours watched. Washing machine: cycle time × loads/week ÷ 7. Lighting: hours lights are on. Computer: work + gaming time.
- What is a time-of-use tariff?
- Time-of-use (TOU) tariffs have lower rates at night (usually 10PM-6AM) and higher during the day. Worth it if >30% of usage is at night (e.g., water heater, laundry at night, EV charging).
- Why is my bill higher than the calculation?
- Bills include: fixed fees (distribution, service charges), taxes, and other surcharges. In advanced mode, you can add fixed fees and taxes to get closer to your actual bill.
- Is my data safe?
- Yes. All data is stored only in your browser (localStorage). We don't send it to any server. You can export it as a JSON file or delete it completely with the "Clear data" button.
- How much electricity does a fridge use?
- A typical fridge uses 100-200W and runs 24 hours a day. That's about 72-144 kWh per month, costing $10-22 at $0.15/kWh. Energy-efficient models (A+++) use closer to 100W.
- How much does it cost to run a gaming PC?
- A gaming PC uses 300-500W under load. At 6 hours/day and $0.15/kWh, that's 54-90 kWh/month or $8-14/month. Add a monitor (30-50W) and peripherals for the full picture.
- How much electricity does a washing machine use?
- A washing machine uses 400-500W per cycle (about 1 hour). At 8 loads per month, that's 3.2-4 kWh/month — only $0.50-0.60. Heating water uses the most energy, so cold washes save significantly.
- How can I reduce my electricity bill?
- Top strategies: switch to LED bulbs (save 80%), unplug standby devices (save $50-100/yr), use a smart power strip, run appliances during off-peak hours if you have a TOU tariff, and upgrade to energy-efficient appliances.
- How much does air conditioning cost to run?
- A typical AC unit uses 1000-1500W. Running it 8 hours/day at $0.15/kWh costs $36-54/month. Use a programmable thermostat and set it to 24-25°C (75-77°F) for the best balance of comfort and cost.
- How much does 1 kWh of electricity cost?
- Average US residential rate: about $0.16/kWh (national average 2024). UK average: about £0.24/kWh (Ofgem price cap). Germany: ~€0.31/kWh. France: ~€0.23/kWh. Rates vary by state/region, provider, and time of year — check your latest electricity bill for your exact rate.
- How much is the average monthly electric bill?
- US average: around $117/month (EIA 2023). UK average: about £60-80/month. Varies significantly by home size, climate, and appliances. A well-insulated 3-bedroom home with efficient appliances can stay under $80/month, while homes with electric heating or AC in hot climates often exceed $150/month.
- How much electricity does a space heater use?
- A portable space heater typically uses 750W (low) or 1500W (high). Running at 1500W for 8 hours/day costs about $0.18/day or $5.40/month at $0.15/kWh. For whole-room heating, it's usually far cheaper to use central heating instead of running multiple space heaters.