Rex says
Everyday utility math — the kind you'd otherwise pull up four browser tabs for. I keep it to one clean answer.
Try a scenario
Click to load — tweak from there.Inputs
Result
Monthly cost
$24.48
Daily cost
$0.82
Annual cost
$294
Monthly kWh
144.0
Annual kWh
1,728
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter device wattage (W).
- 2Enter hours used per day.
- 3Enter days used per month.
- 4Enter electricity rate ($/kWh).
- 5Read your monthly cost on the right — it updates as you type.
- 6Hit Share to keep the scenario or send it to someone.
About this calculator
Multiply watts by hours to get watt-hours, divide by 1,000 for kWh, then multiply by your rate. Always-on devices are the sneaky ones — a 60 W device left running all year costs more than a 1,500 W heater used occasionally.
Worked example
Using the values the calculator loads with:
Inputs
- Device wattage: 1200 W
- Hours used per day: 4
- Days used per month: 30
- Electricity rate: 0.17 $/kWh
Results
- Monthly cost: $24.48
- Daily cost: $0.82
- Annual cost: $293.76
- Monthly kWh: 144
- Annual kWh: 1,728
What each field means
Inputs
- Device wattage (W)
- The device wattage used in the calculation, measured in W. Starts at 1200 W so you have a working example on load.
- Hours used per day
- The hours used per day used in the calculation. Starts at 4 so you have a working example on load. Accepted range: 0–24.
- Days used per month
- The days used per month used in the calculation. Starts at 30 so you have a working example on load. Accepted range: 0–31.
- Electricity rate ($/kWh)
- The electricity rate used in the calculation, measured in $/kWh. Starts at 0.17 $/kWh so you have a working example on load.
Results
- Monthly cost
- Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Daily cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Annual cost
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Monthly kWh
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Annual kWh
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How does the electricity cost calculator work?
Multiply watts by hours to get watt-hours, divide by 1,000 for kWh, then multiply by your rate. Always-on devices are the sneaky ones — a 60 W device left running all year costs more than a 1,500 W heater used occasionally. The underlying maths is: Cost = Watts ÷ 1000 × Hours × Rate.
What do I need to enter?
4 values: device wattage, hours used per day, days used per month, and electricity rate. Each field starts with a sensible default, so you can change one number at a time and watch the result move.
What does the monthly cost result mean?
It is returned as a money amount in US dollars and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds.
Is this calculator free, and do I need an account?
Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser.
How accurate is the result?
It applies the standard formula exactly, so the arithmetic is precise. Estimates assume standard, average conditions — local rules, pricing, and materials vary.
Who is this tool for?
It's built for anyone doing everyday planning maths — a quick estimate that would otherwise need four browser tabs and a calculator app.
Accuracy and limitations
- Estimates assume standard, average conditions — local rules, pricing, and materials vary.
- Results are rounded for readability; add a buffer before ordering, booking, or committing.
- Double-check anything with a real cost attached against a local quote.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Electricity Cost Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/electricity-cost
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/electricity-cost" target="_blank" rel="noopener">Electricity Cost Calculator — RevenueLab</a> (2026).</p>
Source: [Electricity Cost Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/electricity-cost) (2026).