Electricity Cost Calculator: How to Calculate Your kWh Bill and Reduce It
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What Is a Kilowatt-Hour (kWh) and Why It Is the Only Number That Matters
Your electricity bill is measured in kilowatt-hours (kWh). One kWh = 1,000 watts of power used for 1 hour. That is a 100-watt light bulb running for 10 hours, a 1,000-watt microwave running for 1 hour, or a 2,000-watt heater running for 30 minutes — all equal 1 kWh.
To calculate what anything costs to run:
Cost = (Watts ÷ 1,000) × Hours used × Price per kWh
Find your price per kWh on your electricity bill (it varies by country, supplier, and tariff). Average rates in 2026: US ~$0.16/kWh, UK ~£0.25/kWh, Australia ~AUD $0.30/kWh, India ~₹6–9/kWh.
Calculate the Running Cost of Any Appliance
Use the formula above with these typical wattages:
| Appliance | Typical Wattage | Cost per Hour (at $0.16/kWh) | Cost per Day (typical use) |
|---|---|---|---|
| LED light bulb | 8–12W | $0.0016 | $0.001 (6 hrs) |
| Laptop | 45–65W | $0.009 | $0.06 (8 hrs) |
| Desktop computer + monitor | 200–350W | $0.045 | $0.27 (8 hrs) |
| Refrigerator (modern) | 100–200W (cycling) | $0.016 avg | $0.38 (24 hrs) |
| Washing machine | 500–1,500W | $0.16 | $0.32 (2 cycles) |
| Tumble dryer | 2,000–5,000W | $0.48 avg | $0.96 (2 loads) |
| Electric oven | 2,000–5,000W | $0.50 | $0.50 (1 hr) |
| Air conditioning (room unit) | 900–2,500W | $0.27 | $1.62 (6 hrs) |
| Air conditioning (central) | 3,000–5,000W | $0.64 | $3.84 (6 hrs) |
| Electric water heater | 3,000–4,500W | $0.60 | $1.20 (2 hrs) |
| EV charging (Level 2, 7.2kW) | 7,200W | $1.15 | $11.52 (10 hrs) |
Calculate Your Monthly Electricity Bill
Step 1: List all appliances in your home, their wattage (on the label or spec sheet), and daily hours of use.
Step 2: For each: (Watts × Daily hours) ÷ 1,000 = daily kWh
Step 3: Sum all daily kWh values = total daily kWh
Step 4: Daily kWh × 30 = monthly kWh
Step 5: Monthly kWh × price per kWh = monthly electricity cost
Use our Electricity Cost Calculator to do this instantly for any number of appliances.
Worked Example: A Typical 3-Bedroom Home (US)
| Appliance | Watts | Daily Hours | Daily kWh |
|---|---|---|---|
| Refrigerator | 150 | 24 (cycling) | 0.9 |
| Lighting (10 LED bulbs) | 100 | 5 | 0.5 |
| TV (55") | 130 | 4 | 0.52 |
| Laptop × 2 | 110 | 6 | 0.66 |
| Washing machine | 1,000 | 0.5 (avg) | 0.5 |
| Dryer | 3,000 | 0.5 (avg) | 1.5 |
| Water heater | 3,500 | 1.5 | 5.25 |
| HVAC | 3,500 | 3 | 10.5 |
| Total daily kWh | 20.33 |
Monthly: 20.33 × 30 = 610 kWh. At $0.16/kWh: $97.60/month. This is close to the US average of $115/month (EIA 2025), with HVAC being the dominant cost.
The 5 Biggest Electricity Savings in Any Home
Based on typical household energy breakdowns, these changes deliver the highest return:
- HVAC efficiency: Responsible for 40–50% of electricity use in many homes. Setting the thermostat 1°C (2°F) lower in winter or higher in summer saves 3–5% on heating/cooling costs.
- Water heater: Setting water heater to 49°C (120°F) instead of 60°C (140°F) can reduce water heating costs by 6–10%.
- Dryer → line drying: Eliminating tumble dryer use saves $150–$200/year for the average household.
- Switch to LED: LED bulbs use 75–80% less energy than incandescent. Full home switch saves $75–$200/year.
- Standby power ("vampire loads"): Electronics on standby use 5–10% of total home electricity. Power strips with switches eliminate this for entertainment centers and home offices.
Understanding Your Electricity Bill: Key Terms
- Unit rate / energy rate: The per-kWh price you pay for electricity consumed
- Standing charge / daily service charge: A fixed daily fee regardless of usage (US: $0.10–$0.50/day; UK: ~£0.60/day)
- Time-of-use tariff: Different rates for peak (e.g. 4–9pm) vs. off-peak hours — can save 20–40% if you shift usage to off-peak
- Demand charge (commercial): Based on peak power draw in a billing period — very different from residential billing
Related Calculators
- Electricity Cost Calculator — Calculate cost for any appliance or room
- Home Energy Cost Calculator — Full home energy breakdown
- Fuel Cost Calculator — Compare electricity vs. gas heating costs
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In-Depth Guides
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Frequently Asked Questions
Our Methodology
All tools content on CalculatorApp.me is reviewed by subject-matter experts, cross-referenced with official sources, and updated regularly for accuracy. Our formulas and data are verified against industry standards and government publications.
Jordan Hayes
Verified AuthorLead Content Editor & Personal Finance Specialist
Jordan Hayes is a personal finance content strategist with 9+ years building educational finance and health resources. He has written and fact-checked over 200 personal finance guides covering mortgage amortization, retirement planning, tax strategy, and budgeting. His work applies IRS publications, Federal Reserve data, and peer-reviewed research to make complex calculations accessible.
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