The electricity bill arrives, the amount is shocking, and the same question always arises: who spent all that money? The answer is rarely found in what you remember using. It's in three or four appliances that operate silently, some of them running twenty-four hours a day.
The good news is that you don't need to guess. There's a simple calculation that tells you, in reais (Brazilian currency), how much each appliance in your home costs per month. This guide shows the calculation, applies it to each appliance, and concludes with what you can do today.
The account that resolves the discussion.
Every appliance has a power rating in watts, indicated on its label or in its manual. The formula is as follows:
(Power in watts × hours of use per day × 30) ÷ 1,000 = monthly consumption in kWh
Then simply multiply the result by the price per kWh. And here's the most important detail from the guide: Use the price that is in your account., This is not an average internet rate. The rate varies by provider, state, and the tariff flag for the month.
To give a sense of scale, the average residential tariff in the country is around R$ 0.85 per kWh, but the difference between the most expensive and the cheapest distributor exceeds twenty cents per kWh, and there are states with averages well above that. The regulatory agency projected an average increase of around 8% for tariffs in 2026.
In the examples below, I use R$ 0.85 per kWh. Redo it with your own number.
Electric shower: the most powerful tool in the house.
No household appliance comes close: the shower works between 4,000 and 8,000 watts, depending on the resistance and position of the key.
A family of four, taking 15-minute showers a day, consumes approximately 120 kWh per month In the shower alone — something around R$ 100 in the example tariff. In many homes, this represents between 20% and 30% of the entire bill.
What works: using the warm setting instead of hot drastically reduces consumption because the heating element operates at a lower power. And cutting your shower from 15 to 10 minutes saves about 30% of shower energy, without any detriment to hygiene.
Air conditioning: the champion of summer.
A typical window device pulls between 1,000 and 1,500 watts in operation. Eight hours a day in the summer means something between 240 and 360 kWh per month — from R$ 200 to R$ 300 in the example tariff, only in that example.
Older models consume significantly more fuel than current models with good efficiency ratings, and the difference appears on the bill as a separate charge.
The setting that yields the best return is temperature: Raising the temperature by two degrees reduces consumption by approximately 10%.. Cleaning the filter regularly is also important, because a dirty filter forces the compressor to work harder for the same result.
Refrigerator: low power, high consumption.
This is the perfect example of why wattage alone is deceiving. The refrigerator uses somewhere between 400 and 800 watts, much less than the shower—but it stays on. all year round, without stopping.
A typical refrigerator consumes... 100 to 200 kWh per month. Older models exceed 300 kWh due to less efficient motors and worn seals.
What really reduces costs: keeping the sealing rubber in good condition, not placing the appliance against the wall, keeping it away from the stove and direct sunlight, and not opening the door unnecessarily. Just the placement, in a cooler corner of the kitchen, can save close to 15%.
It is also the appliance where upgrading to an energy-efficient model usually pays for itself the fastest, precisely because consumption is continuous.
Washing machine
Consume between 2,000 and 3,500 watts during the cycle. With three to four washes per week, it gives something between 30 and 50 kWh per month.
What matters here isn't so much the machine itself, but the habit: accumulating full loads instead of washing small amounts of laundry several times reduces the number of cycles, which is what really counts. An economy cycle for lightly soiled clothes and washing with cold water complete the savings.
Television and on-demand consumption
A 50-inch TV uses between 80 and 150 watts when switched on. Five hours a day adds up to approximately... 15 kWh per month — very little, compared to the rest.
What often goes unnoticed is standby mode. Even when switched off via the remote, the device continues to consume power: a cable TV receiver can draw 15 to 20 watts continuously, the equivalent of an LED light bulb being on day and night.
In a house with several appliances plugged in — TV, receiver, stereo, microwave with clock, chargers plugged into the wall — the total usually ranges between 50 and 100 kWh per month. It's not the biggest culprit, but it's the easiest to eliminate: a power strip with a switch solves the problem.
Iron, electric oven and hairdryer
They are all high-powered and short-lived. Irons range from 1,000 to 2,000 watts; hair dryers, between 1,500 and 2,000; electric ovens can exceed 2,000 watts.
Since usage is intermittent, the total monthly cost is usually modest—unless the frequency is high. Ironing clothes all at once, with the iron already hot, is more efficient than turning it on and off several times a week.
How to find your villain in ten minutes.
- Take the bill and note the total monthly consumption in kWh and the price per kWh.
- List the high-power devices. Home appliances: shower, air conditioning, refrigerator, washing machine, oven.
- Estimate usage hours Give honestly to each person each day.
- Apply the formula in each one.
- Some. If the total was close to the bill's consumption, you found the culprits. If it was much lower, there was hidden consumption—usually waiting, an old refrigerator, or an appliance left on.
What changes the bill later this month?
- Shower switch to the warm position. whenever the temperature allows.
- Air conditioning two degrees higher than what you usually use.
- A shower five minutes shorter.
- Power strip with switch for the TV set, switched off at night.
- Keep the refrigerator away from the stove. and with the seal provided.
- Washing clothes with a full load and in cold water.
- Replacing an old light bulb with an LED., If there are any left.
Common questions
Which appliance consumes more energy: a shower or a refrigerator?
The shower has much higher power, but it only stays on for a few minutes. The refrigerator has low power and never turns off. In typical calculations, the two compete for the top spot, and the result depends on the size of the family and the age of the refrigerator.
Leaving a charger plugged into a dead outlet?
It consumes very little energy, almost irrelevant in isolation. The habit is more valuable for safety and the lifespan of the charger than for saving money.
Does the tariff flag change much?
Change. The flag is an additional charge per kWh that varies according to the generation conditions in the month. With a red flag, the same household pays more for the same consumption.
Is it worth replacing an old refrigerator?
It's usually worth it when the appliance is quite old, because the difference in consumption is large and recurring. Compare the estimated monthly consumption of the new model with what you spend now and see how many months it takes for the difference to cover the price.
Does the efficiency label really matter?
It matters, and the return is greater the more the appliance is used. For refrigerators and air conditioners, this is the most relevant information at the time of purchase.
Does the energy consumption measurement app work?
An app that only estimates using a formula does what you can do yourself. A real measurement requires a wall-mounted meter, which is inexpensive and resolves the question of needing a specific device.
Summary
Take your electricity bill, check the price per kWh, and calculate the consumption for the four most powerful appliances in your house. In ten minutes, you'll go from feeling it to seeing the numbers—and discover that, in most Brazilian homes, the battle for first place is between the shower and the refrigerator.
