Electricity Cost Calculator
Quick explanation
Estimate appliance running cost using wattage, daily runtime, billing days, and utility rate. This calculator combines energy and price in one flow: Cost = ((W × h × days) / 1000) × rate. For more context on the math, read the how to calculate appliance running cost guide.
Estimated energy cost: $21.6
Estimated usage: 135 kWh
How to estimate appliance electricity cost
Most utility bills charge by kilowatt-hour (kWh). To estimate cost, first calculate kWh used over your billing period, then multiply by your utility rate.
This page is useful for comparing appliance choices and usage habits, such as reducing runtime or shifting to lower-power devices.
It is also a practical way to sanity-check whether a high-draw device is likely driving a noticeable increase in monthly spend.
How to convert
Cost formula from watts
Convert power and time into kWh, then apply your rate.
Cost = ((W × h × days) / 1000) × rate
kWh = (W × h × days) / 1000
Alternative form
If you already know total kWh for the period, multiply directly by the rate.
Cost = kWh × rate
Worked examples
Question: What does a 1500W heater cost at 3 h/day, 30 days, and $0.16/kWh?
Solution: kWh = (1500 × 3 × 30) / 1000 = 135; Cost = 135 × 0.16 = $21.60
Question: What does a 100W fan cost at 10 h/day, 30 days, and $0.18/kWh?
Solution: kWh = (100 × 10 × 30) / 1000 = 30; Cost = 30 × 0.18 = $5.40
Question: What does a 12W LED bulb cost at 6 h/day, 30 days, and $0.20/kWh?
Solution: kWh = (12 × 6 × 30) / 1000 = 2.16; Cost = 2.16 × 0.20 = $0.432
Common mistakes and notes
- Use realistic daily runtime, not just maximum runtime.
- Tiered and time-of-use billing can produce higher or lower actual costs.
- Round utility rates carefully; small rate differences can change monthly totals.
Assumptions
- Uses a fixed average utility rate and steady power draw.
- Tiered rates, demand charges, taxes, and fixed service fees are excluded.
- Use this as a planning estimate before final budget decisions.
Worked example
Example: 1500W used 3 hours/day for 30 days at $0.16/kWh costs about $21.60.
FAQ
How do you calculate electricity cost?
Compute total kWh, then multiply by your rate: cost = kWh × ($/kWh).
What rate should I use?
Use the all-in energy rate from your utility bill when possible.
Why can my bill be higher than this estimate?
Bills often include fixed charges, tiered pricing, and taxes not included here.
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⚠️ Sanity Check Only
This tool provides informational estimates only. It is not professional engineering advice. Electrical work is dangerous and governed by strict local codes.
Before you start:
- Verify these results with a licensed electrician.
- Cross-reference with the latest Electrical Code (NEC/CEC).
- Never work on live circuits.