Electricity Cost
Calculates the electricity cost of a device list from power, daily use and tariff.
We never assume a default — find yours on your electricity bill, usually next to "Energy" or "Consumption", as a unit value in R$/kWh.
Enter the extra R$/kWh for the flag in effect this month (yellow, red 1 or red 2) to include it in the simulation. See "What is the tariff flag system" in the content below.
Estimated cost
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What this tool does
Builds a list of devices — picked from a ready-made list with reference power, or typed from scratch — and calculates the estimated energy cost of each one and of the total, across three horizons: per day, per month and per year. No data leaves the browser: the whole calculation is a simple formula (power × usage time ÷ 1000 × tariff), with no network call.
The list's power is a reference, not your specific device's value
A device's real power varies by model, brand and, for electric showers, even by voltage and season — a shower ranges from ~3,200W to ~9,000W depending on model and setting. The pre-filled values come from real sources (manufacturer manual, official INMETRO/PBE table) documented in detail in the product's repository, but they represent a common reference, not your specific device. Whenever you know the real power (printed on the label or product manual), type it into the "Power (W)" field instead of the pre-filled value — the result gets more accurate.
Hours per day accepts fractional values
Few devices run a whole number of hours a day — a shower usually lasts 10 to 20 minutes (0.17 to 0.33 hour), ironing rarely goes past 30 minutes (0.5 hour). Type the corresponding fraction using a comma or a period ("0,25", "0.25") — the field accepts both.
What the tariff flag system is, and why it isn't automatic here
Brazil's ANEEL tariff flag system signals, every month and nationwide, whether the cost of generating electricity is higher than normal (for example, when hydroelectric reservoirs run low and pricier thermal plants must be turned on) — the green flag charges nothing extra, while yellow and the two red flags add a surcharge per kWh consumed, published by ANEEL every month. This tool doesn't automatically look up which flag is in effect: that would require maintaining a live value that changes every month, in the same class of ongoing maintenance the Nexinon reserves for dedicated live-data features. Instead, the "Tariff flag surcharge" field accepts the R$/kWh value directly, which you can find on ANEEL's website or on your own electricity bill.
Why the refrigerator already comes with "24 hours a day" filled in
Unlike the other devices in the list, a refrigerator doesn't turn on and off by choice — it stays plugged in all day, and the compressor cycles on and off by itself to keep the temperature. The official INMETRO label never states an instantaneous power in Watts for refrigerators, only the average monthly consumption in kWh/month; the pre-filled value in the list is that official monthly consumption converted into an average continuous power (kWh/month ÷ 30 days ÷ 24 hours × 1000). That's why the "Hours per day" field already starts at 24 for this device — it's the only setting physically consistent with a value that already represents a full-day average; changing that number wouldn't reflect any real way a refrigerator is actually used.
Known limitations
The calculation assumes a constant tariff and flag surcharge across the whole period — it doesn't model time-of-use tariffs (different price by hour) nor extra taxes and fees on the bill (VAT-equivalent taxes, public lighting contribution, or flags some utilities already fold in differently from ANEEL). The list's reference power values are a common market range, not a measurement of your specific device — use the free power field whenever you know the real value. "Per month" uses 30 days and "per year" uses 365 days, each computed directly from the daily cost (neither one multiplies the other), so the three numbers stay consistent with each other, but won't exactly match any specific calendar month or year.
Frequently asked questions
Electric showers vary a lot — from ~3,200W to ~9,000W — depending on model, voltage (127V or 220V) and even a summer/winter setting. The pre-filled value is a common market reference, not a measurement of your device. Check the power printed on your shower's label or manual and type it into the "Power (W)" field.
Because the refrigerator's reference power is already an AVERAGE continuous value (calculated from the official monthly kWh consumption, not an instantaneous power) — it only makes mathematical sense multiplied by the full 24 hours of the day, since that's how it's always plugged in. Changing the hours to anything else would stop reflecting any real refrigerator usage.
It's a monthly signal from ANEEL about the cost of generating electricity in Brazil that month — the higher it is, the bigger the surcharge per kWh. That information changes every month and would require maintaining an always-current live value, outside this tool's scope; instead, you enter the value (found on ANEEL's website or on your own electricity bill) directly into the optional field.
On your utility's invoice, usually next to "Energy" or "Consumption", as a unit value in R$ per kWh. That number varies by utility and by state, which is why the tool never assumes a default.
A "900W" microwave refers to its cooking power (what it delivers to the food), not its actual draw from the outlet, which is always higher — the list uses the nominal (consumption) power, the same one measured on the official INMETRO label. The laptop's value is its official charger capacity, useful as a ceiling — real average usage tends to be well below it.
They're an estimate, not an exact copy of your bill: they assume a constant tariff and flag surcharge, 30 days per month and 365 per year, and don't include extra taxes/fees from the bill. Useful for comparing the relative weight of devices and simulating usage changes, not for predicting the exact amount of your next bill.
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