How to Lower Your Electricity Bill and Find the Appliance That Consumes the Most Energy
Put Rodrigo Pereira
The bill is higher than last month's, and nobody at home has changed anything. Except the new air fryer arrived. The air conditioner is now left on all night. The video game console sleeps with the red light on.
One of these devices is driving up your bill. A simple multiplication test points to the suspect, and a smart plug connected to your phone confirms the number. Here's the complete breakdown: the formula, the devices that usually top the list, the app that shows the usage of each one, and five cost cuts that will take effect on your next bill.
A simple calculation: watts × hours ÷ 1,000
Every electricity bill is calculated in kilowatt-hours, or kWh. To arrive at this number, you only need two pieces of information: the power in watts, printed on the appliance's nameplate or in the manual, and the time it is switched on.
The formula is: Power (W) × hours of use ÷ 1,000 = kWh.
Does the nameplate show wattages? If it shows volts and amps, multiply the two. A 220V, 5A appliance is close to 1100W. See the bill for common appliances in a 30-day month:
- Air conditioner with 1,000 W, 8 hours per night: 1,000 × 8 ÷ 1,000 = 8 kWh per day. Up to 240 kWh per month.
- 2,500 W clothes dryer, 1-hour cycles, 12 times a month: 2.5 kWh per cycle, 30 kWh per month.
- 1500W air fryer, 20 minutes a day: 20 minutes is one-third of an hour, so 1500 ÷ 3 = 500 Wh, or 0.5 kWh per day. In a month, that's 15 kWh.
- 200W video game, 3 hours a day: 0.6 kWh per day, 18 kWh per month.
- 10W router, plugged in 24 hours a day: 0.24 kWh per day, 7.2 kWh per month.
Now for the money. Each distributor charges a price per kWh, and it appears on the bill. Just as an example: if the kWh costs 1.00 in your currency, the air conditioner above could cost up to 240.00 per month, and the router would cost 7.20. Replace the 1.00 with your exchange rate, and the calculation is valid in any country.
The usual suspects
The calculation reveals a clear pattern. The heaviest devices fall into three groups:
- Those that heat up or cool down: Electric shower, heater, air conditioner, oven, dryer, iron, and electric kettle. They have the highest power ratings in the house, so half an hour already leaves its mark.
- Those who never switch off: Refrigerator, freezer, and router. Low or medium power, but 24 hours a day, all year round.
- Those who pretend to have turned it off: TV, set-top box, video game console, and speaker system in standby mode. A set-top box that draws 8W in standby mode for 20 hours a day adds up to 4.8 kWh per month. On its own, that's not much. But when added to the others, it becomes significant.
Refrigerators and air conditioners have a catch: the compressor turns on and off automatically throughout the day. The power rating on the label shows the maximum consumption, not the actual usage. For these two, you'll have to measure them.
SmartLife: the expense meter that fits in your pocket
SmartLife is a smart home hub for products sold by many different brands: outlets, light bulbs, sensors. It has a 4.8 rating on Google Play, over 1.3 million reviews, and more than 50 million downloads. On the Brazilian App Store, it has a 4.7 rating. It's a free download.
One point needs to be clear: the app alone doesn't measure anything. It's a system that does the measuring. Smart plug with energy consumption metering, compatible with SmartLife.. It sits between the wall and the device, and the numbers reach the cell phone through the home network.
- Energy on screen: The app tracks the energy consumption of devices plugged into these outlets and helps you see where your bill is increasing.
- Remote control: Turn devices on and off via your cell phone, from anywhere with internet access.
- Automation: Establish rules for devices to turn themselves on and off automatically.
- Voice command: You can ask instead of touching.
Before buying, read the packaging looking for three pieces of information: the Smart Life app seal or mention, the words "energy measurement" (or "energy monitoring"), and the maximum current in amperes. This must be greater than the current drawn by the plugged-in device.
Step by step: your household spending ranking on SmartLife
- Install SmartLife using the button at the top of this page, on Google Play, or in the App Store, and register.
- Plug the smart plug into a regular power outlet near the device you want to investigate.
- In the app, tap "add device" and follow the pairing process with your home Wi-Fi.
- Plug the first suspect into the smart plug: the video game console, the TV, the computer.
- Use the appliance as usual. A full day is enough for most people. Refrigerators and air conditioners require a week.
- Tap the card on the outlet and look for the accumulated consumption in kWh. The name and design of this screen vary from one manufacturer to another.
- Multiply the kWh by the tariff and write the value down on a piece of paper or in your phone's notes app.
- Move the plug to the next appliance and repeat. In a week or two, the list from most expensive to least expensive will be ready.
Electric showers, built-in ovens, and tankless water heaters are usually connected directly to the electrical panel, without any outlets in between. For these, use the formula from the beginning.
TP-Link Tapo: Estimated cost in money
Tapo is the app for TP-Link's smart plugs and cameras. It has a 4.8 rating on Google Play, over 10 million downloads, and a 4.7 rating on the Brazilian App Store. Its key differentiator is the pricing: with a Tapo plug that measures energy, like the P110, you register the kWh price and the app estimates how much the plugged-in device adds to your bill. The same plug accepts scheduled times, countdown timers, and automatic shut-off after a period of use.
Xiaomi Home: for those who have a Xiaomi plug
Xiaomi Home controls Xiaomi's smart home line. It has a 4.8 rating on Google Play and has over 50 million downloads. With the Xiaomi Smart Plug 2, the app shows real-time consumption and detailed usage statistics, and alerts you when the outlet detects overcurrent or overheating.
Five cuts that bring down the bill.
- Two fewer hours of air conditioning per night: With a 1,000 W appliance, that's up to 2 kWh per day and 60 kWh per month. A timer that switches off overnight does this for you.
- Clothesline instead of a dryer: Each cycle avoided in the 2,500 W dryer saves 2.5 kWh. Eight fewer cycles per month saves 20 kWh.
- Air fryer instead of oven for small portions: A 2,000 W oven running for 45 minutes consumes 1.5 kWh. A 1,500 W air fryer running for 20 minutes consumes 0.5 kWh.
- Standby mode disabled at night: A power strip with a button, or an automation system in a smart outlet, can turn off the TV, video game console, and set-top box all at once.
- Label read before purchase: Many countries require an energy efficiency label that indicates the estimated energy consumption of the appliance in kWh. Compare two models in the store and the difference will be reflected in all bills for years to come.
Which app to choose?
| Application | Best for | Note on Google Play | Downloads |
|---|---|---|---|
| SmartLife | View the power consumption of each appliance, using different brands of plugs. | 4,8 | 50 mi+ |
| TP-Link Tapo | View the estimated cost with your registered rate. | 4,8 | 10 mi+ |
| Xiaomi Home | Xiaomi smart plugs | 4,8 | 50 mi+ |
| Watts x Hours | Shower, built-in oven, and anything that doesn't fit through an electrical outlet. | – | – |
To find out who's smuggling your electricity bill this week, try SmartLife: it's a free download, available for Android and iPhone, and compatible with different manufacturers' outlets. Install it using the button at the top of this page, plug the most suspicious appliance into a metered outlet, and see how many kWh it consumes in 24 hours.
