kWh = watts ÷ 1000 × hours
cost = kWh × rate per kWh
1500 ÷ 1000 × 8 = 12.000 kWh/day
12.000 × 0.16 = $1.92/day| Period | Energy | Cost |
|---|---|---|
| Per hour | 1.500 kWh | $0.24 |
| Per day | 12.00 kWh | $1.92 |
| Per month (30 days) | 360.0 kWh | $57.60 |
Source: ProEnergySaver, calculated at $0.16/kWh (US average). Rates cross-checked against EnergyStar, DOE and Ofgem published figures.
Pick the appliances you use and estimate your daily and monthly bill.
UK and many EU/North American suppliers add a fixed daily supply (standing) charge on top of the per-kWh rate.
This tool estimates with an average unit price. Your real bill may differ because of tiered tariffs, seasonal adjustments and surcharges from your utility.
Browser-only
Every calculation runs on your own device. Nothing about your home or your bill is uploaded.
37-52 copyable scenarios
Each guide ships comparison tables and 3 FAQs, cross-checked against Energy Star, the US DOE and Ofgem.
5-region rates
US, UK, Hong Kong, Taiwan and Japan rates are built in, and every figure is editable from your own bill.
This calculator was built for the people who actually get surprised by an electricity bill: renters in the United States and the United Kingdom who pay for power but cannot change the building's wiring, families running an air conditioner through a heatwave or a space heater through a cold snap, and households that added an electric vehicle and suddenly saw their monthly kilowatt-hours jump. It is also built for gamers and remote workers whose desktop, monitors and network gear stay powered for ten or twelve hours a day, and for anyone splitting a shared flat who needs a fair, defensible number instead of an argument. You do not need to know anything about tariffs to use it. Pick the appliances you own, set roughly how many hours a day each one runs, confirm the price per kilowatt-hour printed on your last bill, and you get a daily, monthly and yearly figure you can copy straight into a spreadsheet, a group chat or a note to your landlord.
The tool is private by design. All arithmetic happens in your browser with JavaScript that ships with the page: there is no account, no upload, no server-side record of the appliances you selected, the wattages you typed or the rate you entered. Your region choice is kept in your own browser storage so the page remembers it next visit, and you can clear it at any time by clearing site data. The only measurement we collect is anonymized Google Analytics 4 traffic data, which tells us which pages are read and nothing about individual visitors or their usage inputs. Five regions ship with default residential rates and daily standing charges — the US, the UK, Hong Kong, Taiwan and Japan — and every one of those numbers is editable, because your supplier, tariff and season matter more than any national average. How we source, review and update those figures is documented in our editorial standards, and exactly what is stored is documented in our privacy policy.
ProEnergySaver is written and maintained by Y.W. Fung, an independent energy researcher based in Hong Kong who has spent years reconciling appliance nameplate ratings against real metered household consumption across three very different electricity markets. That background shapes the whole site: wattage defaults are chosen to reflect the equipment people actually own rather than best-case laboratory figures, cost examples are always shown with the rate that produced them, and every guide states its assumptions so you can disagree with them and re-run the numbers yourself. You can read more about the methodology, the data sources and how corrections are handled on our about page.
ProEnergySaver uses the standard energy formula to convert each appliance's wattage and daily hours into kilowatt-hours (kWh), then multiplies by your local rate.
Energy consumption formula
Example: a 1,000 W hair dryer used for 0.5 hours consumes 1,000 × 0.5 ÷ 1000 = 0.5 kWh per day.
Typical wattage and daily runtime for the appliances people ask about most, priced at the United States residential average of $ 0.16 per kWh. Change the rate above and every row is recalculated with your own tariff.
| Appliance | Typical power | Hours / day | kWh / month | Cost / month |
|---|---|---|---|---|
| Inverter air conditioner (large room) | 1,500 W | 8 | 360.0 | $ 57.60 |
| Central AC / heat pump | 3,500 W | 8 | 840.0 | $ 134.40 |
| Window AC unit | 1,000 W | 8 | 240.0 | $ 38.40 |
| Space heater (1500W) | 1,500 W | 6 | 270.0 | $ 43.20 |
| Refrigerator | 160 W | 24 | 115.2 | $ 18.43 |
| Water heater / electric boiler | 4,000 W | 1 | 120.0 | $ 19.20 |
| Tumble dryer (240V) | 3,000 W | 1 | 90.0 | $ 14.40 |
| Washing machine (front loader) | 500 W | 0.8 | 12.0 | $ 1.92 |
| Dishwasher | 1,400 W | 1 | 42.0 | $ 6.72 |
| 65" 4K TV | 150 W | 5 | 22.5 | $ 3.60 |
| Gaming desktop PC | 450 W | 5 | 67.5 | $ 10.80 |
| EV Level 2 charger (240V) | 7,600 W | 3 | 684.0 | $ 109.44 |
| Pool pump | 1,800 W | 6 | 324.0 | $ 51.84 |
| WiFi router | 12 W | 24 | 8.6 | $ 1.38 |
Monthly figures assume 30 days at the usage hours shown. Cycling appliances such as refrigerators and heat pumps draw their rated power only part of the time, so their real monthly total is usually lower than the nameplate figure suggests.
Each one uses the same transparent formula as the calculator above, with pre-run scenarios for the wattages and usage patterns people ask about most. Typical monthly figures are shown at the US average rate of $0.16/kWh.
See what an hour of 1500W heat really adds to a winter bill.
e.g. 42 copyable scenarios$58/mo
Read the full guide →Compare window, portable and split units by BTU and runtime.
e.g. 48 copyable scenarios$46/mo
Read the full guide →Cool one room or the whole house — priced side by side.
e.g. 37 copyable scenarios$150/mo
Read the full guide →Cost per mile and per full charge, Level 1 against Level 2.
e.g. 44 copyable scenarios$55/mo
Read the full guide →Duty-cycle based, so old and new fridges compare fairly.
e.g. 39 copyable scenarios$18/mo
Read the full guide →Vented, condenser and heat pump dryers per load and per year.
e.g. 41 copyable scenarios$22/mo
Read the full guide →Shows why water temperature, not the motor, drives the cost.
e.g. 38 copyable scenarios$9/mo
Read the full guide →Eco cycle against normal cycle, including heated drying.
e.g. 37 copyable scenarios$11/mo
Read the full guide →Idle, browsing and full-load draw for real GPU tiers.
e.g. 45 copyable scenarios$10.80/mo
Read the full guide →Watts and cost by screen size for LED, QLED and OLED.
e.g. 52 copyable scenarios$4/mo
Read the full guide →Tank versus tankless, priced per shower and per month.
e.g. 43 copyable scenarios$44/mo
Read the full guide →Single-speed against variable-speed running hours.
e.g. 40 copyable scenarios$60/mo
Read the full guide →Every figure states the wattage, the hours and the rate per kilowatt-hour that produced it. If you disagree with an assumption you can change it in the calculator and get a number that fits your home instead of a national average.
Each guide carries dozens of pre-run scenarios and a comparison table, so you can grab the line that matches your appliance and usage without doing arithmetic — useful for landlord disputes, flatmate splits and buying decisions.
Wattages are reconciled with Energy Star and US Department of Energy figures, and rates follow EIA and Ofgem publications, with UK standing charges handled separately so fixed costs never get buried inside a per-hour number.
Y.W. Fung is an independent energy researcher based in Hong Kong and the author and maintainer of ProEnergySaver. He has spent years comparing appliance nameplate ratings with metered household consumption across the US, UK and Asian electricity markets, and writes every guide on this site, reviews the regional rate defaults after each regulator update, and answers correction emails personally at hello@proenergysaver.app.
Read more about the author and methodology →HVAC, kitchen, cleaning, tech and high-power categories, plus fully custom appliances.
Built-in residential rates for Hong Kong, Taiwan, the US, the UK and Japan, all editable.
Estimates what you would save each month by shifting heavy loads to off-peak hours.
Share your top energy hogs on social media or embed the calculator on your blog.
Open the page and start; no account, no personal data required.
All calculations are local — your usage data never leaves your device.
US, UK, Hong Kong, Taiwan and Japan rates built in, or type your own.
Responsive layout with large tap targets for quick estimates on the go.
Identify the appliance that started running longer this month.
Compare old vs new wattage and estimate the payback period.
Split the bill fairly based on real usage hours per room.
See how much overnight charging saves compared with peak hours.
It uses watts × hours ÷ 1000 × your rate per kWh, the same formula utilities use to bill energy, so the result is accurate to within a few percent when your wattage and hours are realistic. Real bills also include tiered or block pricing, seasonal rates, taxes and levies, standby draw and duty cycling on thermostat-controlled appliances, so treat the output as a close estimate rather than a billing statement.
No. Every calculation runs in your browser and nothing you type — appliances, wattages, hours or your rate — is sent to a server or stored in any account. Only your region preference is saved locally in your own browser, and site traffic is measured with anonymized Google Analytics 4 that cannot see your inputs.
A standing charge is a fixed daily fee for being connected to the grid, charged in the UK and in several other markets regardless of how much power you use. Tick the standing charge option and enter the pence or cents per day from your bill: the calculator then shows the energy cost and the fixed cost separately, which matters because the fixed part does not fall when you use less electricity.
Yes, and you should. Enter the price per kWh printed on your latest statement at the top of the calculator and every figure updates instantly. The built-in defaults for the US, UK, Hong Kong, Taiwan and Japan are national or capped averages and can differ a lot from your specific tariff.
On time-of-use tariffs, overnight electricity is often 30-50% cheaper than the afternoon peak. Shifting a tumble dryer, dishwasher or EV charge into that window typically saves 10% or more of those appliances' running cost without changing how much energy you use.
A modern refrigerator draws roughly 100-200 watts while the compressor runs, but it cycles on and off, so real consumption is about 1-2 kWh per day, or 30-60 kWh per month — roughly $6-$9 a month at the US average rate. A pre-2000 model can use two to three times that.
Hong Kong, Taiwan, the US, the UK and Japan have built-in residential rates, standing charges and currency symbols. Anywhere else works perfectly well: select the closest region and type your own local rate, since the maths is identical in every market.
Divide watts by 1,000 to get kilowatts, multiply by hours used per day for daily kWh, then multiply by your rate per kWh for daily cost. Multiply by 30 for a month and 365 for a year, then add any daily standing charge separately.
No. This tool is for education only, not utility advice. For informational purposes only — always check your own bill, supplier tariff and meter readings before making a spending, tariff-switching or appliance-replacement decision.
Add a few appliances and see your monthly cost and saving potential in under 30 seconds.
Reference residential rates for Hong Kong, Taiwan, the United States, the United Kingdom and Japan. Real tariffs vary by usage tier, season and supplier, so you can override the rate at the top of the calculator.
| Region | Currency | Rate per kWh |
|---|---|---|
| Hong Kong | HK$ | HK$ 1.4 |
| Taiwan | NT$ | NT$ 3.52 |
| United States | $ | $ 0.16 |
| United Kingdom | £ | £ 0.2565 |
| Japan | ¥ | ¥ 31 |
Air conditioning, electric water heaters, tumble dryers and EV chargers often account for more than half of a household bill. The rank card in this tool shows your top three consumers instantly.
Many regions offer time-of-use tariffs with much cheaper overnight rates. Shifting laundry, dishwashing and EV charging to off-peak hours can cut another 10% or more off your bill.
Set-top boxes, consoles, routers and chargers draw power around the clock. Use switchable power strips and cut them off when you leave home.
Results are estimates for guidance only; your utility bill is the authoritative figure.
See what each appliance really costs per hour, per day and per month — and how to cut it.
Winter heating
Summer cooling
EV ownership
Cooling
Kitchen
Laundry
Laundry
Kitchen
Water heating
Home office & gaming
Entertainment
Kitchen