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Back to OverviewAbout Energy Chart
Free Online Tool
Home Energy Usage Chart
Enter the daily hours of use for your AC, Heater, Fridge, Lights, PC, and Washer — get an instant breakdown of energy consumption, cost estimate, and which appliance is draining your bill the most.
How to Use This Tool (30 Seconds)
- 1Enter Daily Usage Hours: For each appliance — AC, Heater, Fridge, Lights, PC, and Washer — enter the average number of hours it runs per day. Fridge runs 24 hours; most others vary by routine.
- 2Confirm or Adjust Wattage: Each appliance has a pre-filled typical wattage based on industry averages. Override any value with your appliance's actual wattage from its label or manual for a more precise result.
- 3Set Your Electricity Rate: Enter your cost per kilowatt-hour (kWh) from your electricity bill. The default is $0.13/kWh — the US national average — but rates vary significantly by region and provider.
- 4View the Energy Chart: Hit 'Calculate.' The chart renders each appliance's daily and monthly kWh consumption side by side, with a cost breakdown showing each appliance's share of your total bill.
- 5Identify Your Biggest Drain: Read the summary to see which appliance consumes the most energy and how much you could save by reducing its daily usage by just one hour.
The Formula Behind Energy and Cost Calculation
Every result in the chart is derived from the standard kilowatt-hour (kWh) consumption formula used by utility companies worldwide to calculate electricity bills:
// Daily energy consumption per appliance
dailyKWh = (wattage × hoursPerDay) ÷ 1,000
// Monthly consumption (30-day estimate)
monthlyKWh = dailyKWh × 30
// Monthly cost per appliance
monthlyCost = monthlyKWh × ratePerKWh
// Example: AC at 1,500W running 8 hrs/day at $0.13/kWh
dailyKWh = (1,500 × 8) ÷ 1,000 = 12 kWh
monthlyKWh = 12 × 30 = 360 kWh
monthlyCost = 360 × $0.13 = $46.80/month
// Each appliance's share of total bill
share (%) = (applianceKWh ÷ totalKWh) × 100
The kWh unit is what your meter measures and what your bill charges for — not watts. 1 kWh = 1,000 watts running for 1 hour. A 100W light bulb running for 10 hours consumes exactly 1 kWh. This formula is mathematically identical to what your utility provider uses to generate your monthly statement, making the chart's output directly comparable to your actual bill.
Appliance Power Reference — Typical Wattage & Monthly Cost
| Appliance | Typical Wattage | Avg Daily Hours | Monthly kWh | Est. Monthly Cost |
|---|---|---|---|---|
| AC | 900–1,500 W | 8 hrs | 216–360 kWh | $28–$47 |
| Heater | 1,000–1,500 W | 6 hrs | 180–270 kWh | $23–$35 |
| Fridge | 100–400 W | 24 hrs | 72–288 kWh | $9–$37 |
| Lights | 10–60 W | 6 hrs | 1.8–10.8 kWh | $0.23–$1.40 |
| PC | 150–400 W | 8 hrs | 36–96 kWh | $4.68–$12.48 |
| Washer | 500–1,000 W | 1 hr | 15–30 kWh | $1.95–$3.90 |
Cost estimates based on US national average electricity rate of $0.13/kWh (EIA 2024). Actual wattage varies by appliance age, brand, and efficiency rating. Check the label on your appliance for the exact wattage figure.
⚡ Pro Tip
Your fridge is the only appliance in this list that runs 24 hours a day, 365 days a year — making its wattage rating far more impactful than it appears. A 15-year-old fridge consuming 400W costs roughly $37/month to run. A modern Energy Star-certified fridge at 100W costs under $9/month — a $28 monthly saving, or $336 annually, from a single appliance swap. Before adjusting AC or heater usage to reduce your bill, check your fridge's label wattage first. If it is above 200W, replacing it delivers more sustained savings than behavioral changes to any other appliance on the list.
Disclaimer: Cost estimates are for informational purposes only and are based on average wattage and the US national average electricity rate. Actual consumption and costs vary based on appliance efficiency ratings, local utility tariffs, usage patterns, and regional climate. For precise billing data, refer to your utility provider's statement or use a smart plug with energy monitoring.
Frequently Asked Questions
Q: Where do I find the wattage of my appliance?
Check the label on the back or underside of the appliance — it lists voltage (V), amperage (A), and wattage (W) or the information to calculate it. If only voltage and amperage are listed, use: Watts = Volts × Amps. The appliance manual and manufacturer's website also list rated wattage under specifications.
Q: How do I find my electricity rate per kWh?
Your electricity rate is printed on your monthly utility bill — look for a line showing cents or dollars per kWh. In the US, rates range from $0.09/kWh (Louisiana) to $0.29/kWh (Hawaii). In the UK the standard rate is approximately £0.24/kWh. Enter your exact rate for accurate cost results.
Q: Why does the fridge show such high monthly kWh despite low wattage?
The fridge runs continuously — 24 hours a day, 7 days a week. Even at 150W, that is 3.6 kWh daily and 108 kWh monthly. Most other appliances run 1–8 hours daily, making their daily kWh much lower despite higher wattage ratings. Total consumption is always wattage multiplied by hours — never wattage alone.
Q: Does the washer cost include the water heating energy?
The wattage entered for the washer covers the motor and drum only. If your washer is connected to a separate water heater, the heating energy is not included in this chart. For a hot-wash cycle, add 1,500–3,000W for the duration of the heating phase to get the true per-cycle cost.
Q: How much can I save by reducing AC usage by one hour per day?
Using the standard formula: reducing a 1,200W AC by 1 hour per day saves 1.2 kWh daily, 36 kWh monthly, and approximately $4.68 at $0.13/kWh. Over a 5-month cooling season that is $23.40 saved from a single hour reduction — without any equipment change or upfront cost.
Q: Is a desktop PC or laptop more expensive to run?
A desktop PC with monitor typically draws 150–400W. A laptop draws 20–60W — roughly 5–8 times less power for equivalent usage hours. Running a laptop instead of a desktop for 8 hours daily saves approximately 2.4–2.7 kWh per day, or $9–$10.50 per month at the US average rate.
Q: Can this chart account for appliances on standby power?
Standby power — the electricity drawn when an appliance is plugged in but not actively running — is not included in this chart's calculation. Standby typically adds 1–5W per device continuously. For a full household energy audit including standby loads, a smart plug with energy monitoring provides the most accurate per-appliance baseline.