Everyday Calculators
Quick everyday math, solved instantly: EV versus gas costs, what an appliance adds to the power bill, percentages and more. Simple tools on the surface, with verified reference data underneath.
EV vs Gas Cost Calculator
Most "EV vs gas" comparisons online are built on fuel prices from two or three years ago, which makes the answer wrong in both directions. This calculator uses figures verified on September 10, 2026: the AAA national average of $4.151 per gallon of regular gasoline, and the U.S. Energy Information Administration residential electricity average of 18.44 cents per kWh (Electric Power Monthly, May 2026 data). Enter your own mileage, fuel economy and utility rate to see what each car actually costs you per mile — and how much of that gap survives if you charge on public fast chargers instead of at home.
Appliance Electricity Cost Calculator
A space heater feels free because it plugs into a wall. It is not. This calculator turns any appliance into a dollar figure using one simple formula, and it starts from a rate that is actually current: 18.44 cents per kWh, the U.S. residential average published by the Energy Information Administration in its Electric Power Monthly (May 2026 data, verified September 10, 2026, and up about 6% from a year earlier). Pick an appliance, tell it how long the thing runs, and adjust the rate to match your own utility bill.
Ethanol vs Gasoline Calculator (Brazil’s 70% Rule)
Almost every car sold in Brazil is flex-fuel, so drivers face a decision at every fill-up: ethanol or gasoline? Enter both pump prices and this calculator applies the classic 70% rule, showing the break-even ethanol price and how much you save per equivalent liter. Defaults are the ANP national averages for the week of August 2–8, 2026.
Brazil Road Trip Cost Calculator
Planning a drive across Brazil? Enter the round-trip distance, your car’s fuel economy, the pump price and the tolls, and this calculator returns the liters you will burn, the total out-of-pocket cost, the cost per person when the group splits the bill, and the cost per kilometer. The default fuel price is the ANP national average for regular gasoline in the week of August 30 – September 5, 2026.
Percentage Calculator
Four calculations cover almost every percentage question: what X% of Y is, what share one number represents of another, the percentage change between two values, and the reverse question — finding the whole when you only know a part. Pick a mode, type the two numbers and read the answer, along with the related figures that usually come next, such as the discounted price or the multiplier behind a percentage change.
Rule of Three Calculator
The rule of three finds the fourth value of a proportion when you already know the other three. If 3 oranges cost 12, what do 5 cost? If a trip takes 3 hours at 80 km/h, how long does it take at 120? Pick the type — direct, inverse or compound — fill in the fields, and the calculator returns X along with the proportion written out so you can check the reasoning, not just the number.
Brazilian BBQ (Churrasco) Calculator
A churrasco is not a hamburger cookout. Brazilians grill big cuts of beef, chicken and sausage over live charcoal for four to six hours, and the shopping list is built in kilograms, not patties. Enter how many adults, children and beer drinkers you expect, and this calculator tells you exactly how much beef, chicken, sausage, garlic bread, charcoal, beer, soda and ice to buy.
Sleep Cycle Calculator
Waking up groggy is often less about how long you slept and more about when the alarm went off. Sleep runs in cycles of roughly 90 minutes, and being pulled out of deep sleep mid-cycle produces the heavy fog known as sleep inertia. This calculator works backward or forward from your reference time, adds the minutes you take to fall asleep, and returns the wake-up or bedtime options that land at the end of 4, 5 or 6 full cycles. The number beside each option is the total hours of sleep.
Also available in Portuguese: Calculadoras de Utilidades