Online Tool Store
Electricity Cost Calculator
Enter a device's wattage, your electricity rate, and how often you use it to estimate daily, monthly, and yearly running costs. Runs entirely in your browser.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Per day
$0.00
Per month
$0.00
Per year
$0.00
How it works
- Enter the device's power rating in watts.
- Enter your electricity rate, hours of daily use, and days per month.
- Daily, monthly, and yearly costs update instantly.
The formula
Power in watts is converted to kilowatt-hours, then multiplied by your rate:
Cost = (watts ÷ 1000) × hours used × rate per kWh
Example: a 1500W heater run 4 hours a day at $0.16/kWh costs (1500 ÷ 1000) × 4 × 0.16 = $0.96/day.
FAQ
Where do I find my device's wattage?
Check the label on the device or its power adapter — it's usually printed as watts (W) directly, or as volts × amps, which multiply to watts.
Where do I find my electricity rate?
Your utility bill lists a per-kWh rate, often called the "energy charge" — use that number, or check your provider's rate schedule.
Does this account for tiered or time-of-use rates?
No — it uses a single flat rate. If your plan has different rates by time of day or usage tier, treat the result as an estimate using your average rate.
Is my data uploaded anywhere?
No — every calculation happens locally in your browser.
How we compare
| Feature | Online Tool Store | Manual math | Smart plug apps |
|---|---|---|---|
| No smart plug or hardware needed | ✓ | ✓ | ✗ |
| Instant daily/monthly/yearly breakdown | ✓ | ✗ | ✓ |
A smart plug can measure exact usage, but you need to buy and install it first. Electricity Cost Calculator gives you a solid estimate immediately, from numbers you already have.