Number Electricity Cost Calculator
Every appliance has a price per hour — it is just printed in watts instead of dollars. Pick a preset or type any wattage, add how long it runs and your electricity rate, and see what it really costs per day, month and year.
The US average residential rate is roughly $0.17/kWh; your bill’s exact figure is total cost ÷ kWh used. Fridge wattage is an average — it cycles on and off through the day.
How it works
Energy is power × time: watts ÷ 1,000 gives kilowatts, times hours gives kilowatt-hours (kWh) — the unit on your bill. Multiply kWh by your rate for cost. A month uses 30 days and a year 365, so a small daily number gets honest fast: a 1,500 W air conditioner at 6 hours a day is 9 kWh daily, and at $0.17/kWh that is $1.53 a day, $45.90 a month, and $550.80 over a year at that pace.
Formula & worked example
Formula: Kilowatt-hours per day = watts ÷ 1,000 × hours used. Cost = kWh × your rate per kWh. A month is counted as 30 days and a year as 365.
Worked example: A 1,500 W window air conditioner running 6 hours a day uses 9 kWh daily — 270 kWh a month. At $0.17 per kWh that is $1.53 a day, $45.90 a month and $550.80 over a year at the same pace.
When to use this
- A bill jumped and you are hunting which appliance did it, one device at a time.
- You are deciding whether an old appliance is worth replacing by pricing what it costs to keep running for a year.
- A space heater, mining rig or home server is about to run for long hours and you want its cost before, not after.
- You are comparing two homes or tariffs and want a single appliance's cost at a different rate per kWh.
How to use it, step by step
- Pick an appliance preset, or choose custom and type the wattage from the label on your own device.
- Set the hours used per day — honestly, including the hours it sits working while nobody is in the room.
- Enter your electricity rate per kWh from a recent bill: total charges divided by kWh used.
- Read the cost per day, per month (30 days) and per year (365 days), and the matching kWh figures.
- Re-run at the hours you could realistically cut to; the gap between the two runs is the saving on offer.
What the inputs mean
| Input | What it is | Typical values |
|---|---|---|
| Power draw (watts) | How much power the appliance draws while running | LED bulb 10 W; fridge about 150 W average; heater or AC 1,500 W; dryer 3,000 W |
| Hours used per day | Daily running time the cost is based on | Fridge 24 (it cycles); washer about 1; gaming PC 4–8 |
| Electricity rate ($ per kWh) | Your all-in price per kilowatt-hour | US residential average roughly $0.17; real range about $0.11 to over $0.40 by state |
Another worked example
A refrigerator entered at 150 W average draw, running 24 hours a day at a $0.20 per kWh rate: it uses 3.60 kWh a day, costing $0.72 a day, $21.60 a month and $262.80 a year (1,314.00 kWh over the year). The fridge is never the biggest line on a bill, but unlike almost everything else in the house it never gets a day off, which is why its yearly figure surprises people.
Frequently asked questions
How much does it cost to run an air conditioner?
A 1,500 W window unit running 6 hours a day uses 270 kWh a month — about $45.90 at $0.17/kWh, or roughly $550 a year at that pace. A 3,500 W central system at 8 hours a day is 840 kWh a month, around $142.80. Your runtime is the lever: every hour less per day saves about 11%.
How do I find my electricity rate?
Divide a recent bill’s total charges by the kWh used — that blends supply, delivery and fees into the true rate. US residential averages sit near $0.17/kWh, but the real range runs from about $0.11 to over $0.40 depending on state.
What uses the most electricity in a home?
Anything that makes heat or cold: space heating, water heating, AC, dryers and ovens draw 1,500–5,000 W. Lighting used to matter; a 10 W LED costs about $3 a year at 5 hours a day. The preset list above is roughly ranked by typical annual damage.
Is a higher-watt appliance always more expensive?
No — time is the other half. A 3,000 W dryer for 1 hour (3 kWh) costs less than a 500 W gaming PC left on 8 hours (4 kWh). That is why this calculator asks for hours, not just watts.
🎯 Found a monthly leak?
The Savings Goal Calculator turns a found $46 a month into a target date for whatever you would rather buy.
The label on my appliance shows amps, not watts — what do I enter?
Multiply amps by volts to get watts. On a standard US household circuit that is amps times about 120, so a device marked 12 A draws roughly 1,440 W. Use the running amps if the label lists both a start-up and a running figure, because start-up draw lasts only seconds.
Why is my real bill higher than adding up these estimates suggests?
The calculator prices energy only, at one flat rate. Real bills add fixed customer charges and taxes, many utilities charge more per kWh in higher usage tiers or at peak times of day, and cycling appliances are estimated here at a steady draw. Treat the per-appliance figures as a ranking of what to tackle first, not a reconstruction of the bill.