Online Tool Store
· 6 min read
3 Electricity Cost Calculators, Compared Honestly
Manesh Jayawardhana
CIO & Co-founder
You bought a space heater, a mini fridge, or a gaming PC, and now you want a real number: what does it add to your electricity bill if you run it every day? That means turning wattage, hours of use, and your rate per kWh into a daily, monthly, and yearly figure — not guessing from the appliance’s sticker alone.
The trouble is most searches for this land you on results that want your ZIP code and email before they’ll show a number, or ones so packed with appliance presets and regional rate tables that entering your own device’s exact wattage takes longer than doing the math by hand.
How to judge an electricity cost calculator tool
Does it run in the browser, no install. A calculator that needs an app or account for a two-minute estimate isn’t worth the friction.
Is the free tier actually free. Some sites gate custom wattage entry or multi-appliance comparisons behind a signup wall after the first result.
Does your data leave the machine. Entering your rate and usage habits shouldn’t require sending anything to a server — this is arithmetic, not a lookup.
Can you enter your own numbers. Presets are convenient, but if a tool only lets you pick from its appliance list instead of typing the wattage off your own device’s label, the estimate is generic, not yours.
The comparison
| Tool | Best for | Free tier | Watch out |
|---|---|---|---|
| Energy Use Calculator | Broad appliance library with per-hour to per-year breakdowns | Fully free, no signup | Interface is dense with categories, takes a moment to find your exact device |
| WattDoes | Quick look-up using your state’s average electricity rate | Fully free, no signup | Built around US state rate averages, less convenient if you want to enter a specific local rate |
| Appliance Cost Calculator | Comparing several appliances side by side | Fully free, no signup | Regional rate comparisons are US-Census-division based, so non-US users still need to enter a custom rate |
Facts checked August 2026; tools change their plans. Table covers only the 3 alternatives — our tool gets its own section below instead of a 4th row.
Energy Use Calculator
This one is genuinely good at breadth — lighting, kitchen appliances, laundry, electronics, and heating/cooling are all covered with sensible default wattages, and it breaks a result into per-hour, daily, monthly, and yearly cost without extra clicks. It’s a solid pick if you’re not sure what your device draws and want a reasonable starting estimate.
It isn’t the fastest option if you already know your device’s exact wattage from its label — you’ll spend a bit of time scrolling categories to reach the plain custom-entry field.
WattDoes
WattDoes is built for a specific American use case: pick your state, pick from around 60 common appliances, and get a cost using that state’s average rate. For someone who doesn’t know their exact per-kWh rate off the top of their head, that’s a genuinely useful shortcut.
It isn’t the right fit outside the US, and if your utility’s rate differs from your state’s average — which is common — the estimate is a rough one rather than a precise personal figure.
Appliance Cost Calculator
This tool’s strength is comparison: it lets you add several appliances and see them side by side, which is handy when you’re deciding, say, whether the space heater or the window AC is the bigger line item on your bill. Its 60-appliance list and regional rate defaults are a reasonable starting point too.
It’s less useful for a single quick one-off estimate, since the comparison-first layout adds a step that a simple single-device calculator wouldn’t need.
Electricity Cost Calculator
Our tool asks for exactly three numbers — a device’s wattage, your electricity rate, and how often you use it — and returns daily, monthly, and yearly running costs. There’s no appliance list to scroll through and nothing runs on a server; it works entirely in your browser.
The limitation is the flip side of that simplicity: there’s no built-in appliance preset library or state-average rate lookup, so you need your own wattage figure (from the label or a plug-in meter) and your own rate (from a recent bill) before you start.
Which one to pick
If you already have your device’s wattage and your rate per kWh handy, use our Electricity Cost Calculator for the fastest single-device answer.
If you don’t know your device’s wattage and want to pick a common appliance from a list instead, Energy Use Calculator’s broader library is the better starting point.
If you’re in the US and don’t know your exact rate, WattDoes’ state-average shortcut gets you a workable estimate faster.
If you’re deciding between two or three appliances and want them side by side, Appliance Cost Calculator’s comparison view fits that job better than any single-device tool.
How to do it with Electricity Cost Calculator
- Find the device’s wattage, either printed on its label or from the manufacturer’s spec sheet.
- Open the Electricity Cost Calculator and enter that wattage.
- Enter your electricity rate per kWh from a recent bill, and how many hours or days a week you use the device.
- Read off the daily, monthly, and yearly cost estimate. For the full walkthrough, see how to estimate what a device costs to run. Browse more calculators in the tools directory.
You might also need
Once you know what a device costs to run, the next question in a shared household is often who owes what. Our Utility Bill Splitter takes a shared electric bill and divides it across household members, which pairs naturally with knowing what each device actually contributed to that total.
Frequently asked questions
Is there a free electricity cost calculator that doesn’t need an account?
Yes. Our Electricity Cost Calculator, Energy Use Calculator, WattDoes, and Appliance Cost Calculator are all free and require no signup to get a result.
What information do I need before using an electricity cost calculator?
You need the device’s wattage (from its label, spec sheet, or a plug-in power meter), your electricity rate per kWh (from a recent utility bill), and roughly how many hours or days a week you use the device.
How accurate are these appliance running cost estimates?
They’re as accurate as the wattage and rate you enter. Many appliances, like refrigerators and air conditioners, cycle on and off rather than drawing power constantly, so the actual figure is often lower than a “wattage × hours” estimate assuming continuous full-power draw. The U.S. Energy Information Administration publishes average residential electricity rates if you need a reference point.
Final thought
If you already have the wattage and rate in hand, reach for the calculator that asks for just those two numbers and gives you an answer immediately — anything more is solving a problem you don’t have.