Wattwise
What every appliance really costs, before the bill jumps a slab.
Wattwise works out what any appliance costs to run, in your currency, at your tariff, and warns you before this month's bill jumps into the next slab. Pick from 98 presets, move the hours slider, and the daily, monthly and yearly cost updates as you drag. Then the Savings tools show where the money goes. Free with ads, and one small payment removes them.
Designed, built and supported by DevMarDe. Not resold, not white-labelled, and not handed to anyone else after launch. The people who wrote it take the support calls.
- appliance presets across 12 categories
- 98
- appliance presets across 12 categories
- countries with a tariff and voltage already set
- 47
- countries with a tariff and voltage already set
- currencies, shown with their ISO codes
- 40
- currencies, shown with their ISO codes
- languages, two of them right to left
- 11
- languages, two of them right to left
- countries with real peak sun-hour data
- 39
- countries with real peak sun-hour data
- accounts or sign-ins
- 0
- accounts or sign-ins
The cost card is live. Drag the hours slider and daily, monthly and yearly figures move with your thumb, with the kWh beside them. You feel the difference an hour makes.
Enter your tariff slabs once and Wattwise projects this month's units, shows how close you are to the next slab and what crossing it will cost, before the bill arrives.
Read your meter once and Wattwise shows the range it should be in on any day after. Hold the real meter up against it to catch a missing appliance, something left on, leakage or a fast meter.
Type in the units and amount from your real bill. Wattwise shows how much of it your appliances explain, and which big ones are probably missing from your list.
Single rate or slabs, with taxes and fees, and both ways utilities charge slabs: each block at its own rate, or every unit at the rate of the slab reached. Forty-seven countries start with a preset you can edit.
An appliance is charged at its running wattage for the hours it runs and its standby wattage for the rest of the day, adjusted by a duty cycle. That is why a 150 W fridge does not cost 150 W times 24.
Enter the price you were quoted and see the monthly saving, payback years and 25-year total, sized with standard 330 to 700 W panels against real peak sun hours for 39 countries.
What a warmer thermostat or an inverter AC would save each month, and how long your battery keeps the fans, lights and router running through a power cut.
English, Urdu, Arabic, Spanish, Latin American Spanish, Portuguese, German, French, Hindi, Indonesian and Japanese. Arabic and Urdu lay the whole app out right to left.
One payment, priced by where you live
Wattwise is free and stays free. The only thing there is to buy removes the ads, and Google Play charges for it at the tier set for your market rather than converting a single dollar figure, so it is a small amount in Karachi and a small amount in Kansas.
United States, United Kingdom, Canada, Australia, Germany, France, Japan, South Korea, Singapore, Switzerland, Norway, Sweden, Denmark, Netherlands, UAE
Brazil, Mexico, Türkiye, South Africa, Poland, Malaysia, Thailand, Indonesia, Philippines, Colombia, Chile, Portugal, Greece, Saudi Arabia
Pakistan, India, Bangladesh, Nigeria, Egypt and the rest
Paid once, not monthly. Nothing else sits behind it: every preset, country tariff, currency, language and the PDF report are all in the free app.
What Wattwise actually returns
Wattwise's product is its numbers. This table runs the app's own formula over the app's own data. Install it, type the same numbers in, and you get the same answer.
| Preset | Per day | Pakistan₨40/kWh |
|---|---|---|
| Split AC 1.5 TonCooling | 6.39 kWh | ₨7,668per month |
| Inverter AC 1.5 TonCooling | 4.90 kWh | ₨5,885per month |
| Electric Water Heater (Geyser)Bathroom | 3.00 kWh | ₨3,600per month |
| Instant Water HeaterBathroom | 1.82 kWh | ₨2,188per month |
| Refrigerator (Double Door)Kitchen | 1.44 kWh | ₨1,728per month |
| Deep FreezerKitchen | 2.16 kWh | ₨2,592per month |
| Microwave OvenKitchen | 0.40 kWh | ₨481per month |
| Washing MachineLaundry | 0.55 kWh | ₨655per month |
| Clothes IronLaundry | 0.36 kWh | ₨432per month |
| Ceiling FanCooling | 0.75 kWh | ₨900per month |
| Laptop Charger 65WWork | 0.40 kWh | ₨479per month |
| LED Bulb 10WLighting | 0.06 kWh | ₨72per month |
Twelve of the 98 presets, at three of the 47 country rates. The sum is (watts × hours × duty cycle + standby × the rest of the day) × your rate. That is why the refrigerator (double door) costs 1.44 kWh a day and not the 3.60 kWh you get from multiplying the label by 24. Its compressor only runs 40% of the time. Miss that and the number you show someone is frightening and wrong.
What peak pricing does to one air conditioner
Switch peak pricing on and the 5 hours between four and nine in the evening are charged at your peak multiplier (1.35× by default) instead of being averaged into the day. The app states that it spreads usage evenly rather than pretending to know your utility’s schedule.
The sun-hour data Wattwise sizes an array against
Peak sun hours a day, averaged over the year, for twelve of the 39 countries Wattwise carries. The second figure is what six 550 W panels actually make there after that country's own losses come off. Apps that assume five sun hours everywhere promise a British roof about double what it will give you. Outside the 39, Wattwise says it is using a 4.2 hour global average instead of guessing.
98 presets, across twelve categories
Every preset carries its own running wattage, duty cycle, standby draw, voltage, power factor and a realistic run time, so picking one off the list is not the same as typing a number off a label. You can still type your own.
The app, as it ships
Captured from the release app on an Android phone emulator, offline so no ads show. Not mockups.
SetupMonthly cost per appliance, slab warnings and solar payback, set up in under a minute.
Your countryPick where you live and it sets the currency, typical tariff, mains voltage and sun hours.
Your tariffStarts from a typical rate for your country. Copy the exact one from your bill, slabs included.
CalculatorA 1.5 ton split AC at PKR 40 a unit: PKR 7,668 a month, PKR 256 a day.
My HomeEvery appliance with its share of the bill: here four appliances, PKR 12K a month at 9.99 kWh a day.
SavingsSlab Guard projects this month's units and shows what cutting back saves: 100 fewer units drops a slab and saves PKR 3,989.
Meter checkType in your meter reading and Wattwise checks it against what your appliances should have used.
SettingsLanguage, country, currency and a three-slab tariff, all changeable later.
6 modules
- 98 appliance presets across 12 categories
- Single-rate or slab tariffs, with taxes and fees
- Tariff, voltage and sun-hour presets for your country
- Slab Guard, Meter check and Bill X-ray
- Solar payback against your own region's sun hours
- A PDF energy report, saved wherever you choose
- No account; calculations work offline
- Free with ads; one payment removes them for life
- Calculator98 presets in 12 categories or your own wattage, sliders for hours, and a cost card that updates live.
- My HomeEvery appliance you own, grouped by room, with a cost breakdown chart and a total for the house.
- SavingsSlab Guard, Meter check, Bill X-ray, AC Saver, Solar payback, the UPS backup timer and a shareable energy card.
- TariffSingle rate or slabs, taxes and fees, 40 currencies, and a country preset for tariff, voltage and sun hours.
- ReportA room-by-room PDF, saved wherever you choose: Downloads, Drive or an SD card.
- SetupLanguage, country, currency and electricity price on first run. Stored on the phone, nowhere else.
“I wanted to know whether the second AC was worth it before I bought it, not after. You drag the hours and the monthly figure moves. It told me six panels would cover the fridge and the fans, and that turned out to be right.”
Questions people ask
- Is Wattwise free?
- Yes. It is free with ads, the same way most apps are, and one small payment removes the ads for life. Nothing else sits behind that payment: every preset, every tool, the solar payback and the PDF report are all in the free app.
- What does the ad-free purchase cost?
- It is priced by region through Google Play, in 173 countries: around $4.99 in higher-income markets, $1.99 in the middle tier and about $1 everywhere else, charged in your local currency. For example $4.99 in the US, £4.49 in the UK, R$9.99 in Brazil, ₹110 in India and Rs 270 in Pakistan. One payment, not a subscription.
- When can I download it?
- Now. Wattwise is on Google Play for Android, published as dev.wattwise.app, and the button on this page opens the listing.
- Can it tell me before my bill jumps a slab?
- Yes, that is what Slab Guard is for. Enter your tariff's slabs once and it projects this month's units from your appliances, shows how close you are to the next slab and what crossing it would cost.
- Does Wattwise read my meter?
- No, you do. Type in one meter reading and Meter check shows the range the meter should be in on any later day. If the real meter is well outside it, something is missing from your list, left on, leaking or the meter is fast.
- Do I need an account?
- No. There is no sign-up and no login. Your appliance list, tariff and every calculation stay on your phone, and the calculations work without an internet connection. The only thing that uses the internet is the ads.
- How accurate is the estimate?
- It is arithmetic on the numbers you give it: wattage, hours, duty cycle, standby draw, your tariff and its taxes and fees. The solar figures are annual averages for your country rather than a forecast for your roof.
- Which currencies does it support?
- Forty, shown with their ISO codes (USD, PKR, INR, EUR and so on). Switch currency and your rates convert with it.
- Is there an iPhone version?
- Not yet. Wattwise is on Android, published as dev.wattwise.app.
Guides and changelog for Wattwise
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Want Wattwise for your business?
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