The villain on your power bill is not who you think
Ask anyone which appliance dominates the power bill and the answer comes fast: the electric shower — it has the highest wattage in the house, after all. But power is not consumption, and that confusion has people saving in the wrong place all year long.
1. Shower or air conditioner?
A 5,500 W electric shower used 8 minutes a day against a 1,000 W air conditioner running 8 hours a day. The shower draws five and a half times more power. Which one costs more over the month?
2. Work out any appliance
The formula is kWh = watts × hours ÷ 1000, multiplied by the days in the month. Move the controls and watch the cost — and notice how time switched on dominates the result.
3. The real ranking in your home
At a rate of R$0.85 per kWh, this is how appliances actually stack up over a month:
Notice the pattern: the winners are not the highest-wattage devices, but the ones combining moderate power with many hours switched on. Fridges and air conditioners beat the shower on time, not on strength.
Following the power × time logic, the highest-yield actions are: switching the electric shower to its summer setting (it cuts almost half the wattage and is the biggest effect for the least effort); running air conditioning at 23–24 °C, since every degree lower costs real money and inverter units save a lot over long runs; keeping the fridge sealed properly and away from the wall, because it runs 24 hours a day so any inefficiency is constant; and switching bulbs to LED, which cuts that point's consumption by about 85%. Chasing standby power, by contrast, yields little — it adds up to cents, not currency. To find what you pay per kWh, divide the total bill by the month's consumption: that figure already includes taxes and distribution charges.
Run your own appliances
Power, hours of use and rate — with the result in kWh and in money.
Open the Energy Cost Calculator →See also: Energy converter · Lesson: speeding saves less than you think