📖 Overview
Use this tool to estimate electricity bills for appliances and plan your monthly energy budget.
🧪 Example Scenarios
Use these default and higher-pressure example inputs to explore how sensitive this calculator is before using your real numbers.
| Input | Base Case | Higher Pressure Case |
|---|---|---|
| Power (Watts) | 1,000 | 1,150 |
| Hours Per Day | 4 | 4.8 |
| Days Per Month | 30 | 36 |
| Rate ($/kWh) | 0.13 | 0.16 |
⚙️ How It Works
Converts device wattage to kilowatt-hours (kWh) of consumption, then multiplies by usage days and electricity tariff rate to estimate monthly and annual cost.
The Formula
Monthly Cost = (Watts ÷ 1000) × Hours/Day × Days/Month × Rate ($/kWh)
| Watts | Device power rating in watts (found on label or manual) |
| ÷ 1000 | Converts watts to kilowatts (1 kW = 1000 W) |
| Hours/Day | Daily usage hours |
| Days/Month | Days used per month (default 30) |
| Rate ($/kWh) | Your electricity tariff per kilowatt-hour |
💡The average US electricity rate in 2024 is around $0.13/kWh, but it varies from $0.09 (Louisiana) to $0.34 (Hawaii). Check your utility bill for your exact rate.
Quick Reference
| Appliance | Typical wattage | Monthly cost* ($/kWh = 0.13) |
|---|---|---|
| Refrigerator | 150 W | ~$7.02 (24h) |
| Washing machine | 500 W | ~$3.90 (6h use) |
| Gaming PC | 300 W | ~$11.70 (10h) |
| LED bulb | 10 W | ~$0.39 (10h) |
| Air conditioner | 1500 W | ~$58.50 (10h) |
| Electric oven | 2400 W | ~$9.36 (1h) |
When To Use This
- Use this tool when you need a fast decision during active planning or execution.
- Use this before committing money, time, or tradeoffs that are hard to reverse.
- Use this to compare options using the same assumptions across scenarios.
Edge Cases To Watch
- Results can be misleading if key inputs are missing, stale, or unrealistic.
- Very small or very large values may amplify rounding effects and interpretation risk.
- If assumptions change mid-decision, recalculate before acting.
Practical Tips
💡 Always check the device label for actual wattage — manufacturer specs can vary.
💡 Use smart plugs with energy monitoring for accurate real-world consumption data.
💡 Air conditioners and electric heaters dominate household bills — focus here for big savings.
Frequently Asked Questions
❓ Where do I find my electricity rate?
It is listed on your monthly utility bill, usually as cents per kWh.
❓ What is a kilowatt-hour?
A 1000-watt device running for 1 hour uses exactly 1 kWh.
❓ Why is my bill higher than estimated?
Standby power, fluctuating usage, and taxes/fees add to the base energy cost.