How to use the online calculator
Type the calculation on your keyboard or tap the buttons. The expression appears on the display and, as you type, the partial result is shown right below it. When you press = (or Enter) the calculation is evaluated and saved to the history.
- C clears everything; CE deletes only the last number typed; ⌫ deletes one character.
- After calculating, you can keep going from the result by typing another operator.
- Accepts a comma or a dot as the decimal separator.
- Parentheses left open are closed automatically when you calculate.
For specific calculations, also use the compound interest calculator, the SAC and Price financing simulator and the 13th-month salary calculator.
Available operations
Addition
Use +. Example: 1250,50 + 349,90 = 1600,4.
Subtraction
Use −. Negative numbers work too: 5 − 12 = −7.
Multiplication
Use × or the * key. Multiplication is solved before addition, as in math: 8 + 4 × 3 = 20.
Division
Use ÷ or the / key. Dividing by zero has no result, and the calculator shows a warning instead of an invalid value.
Percentage
The % works like on a pocket calculator: 200 × 15% gives 30, and adding or subtracting a percentage applies it to the first value, so 250 − 15% gives 212,5.
Powers and square roots
The xʸ button raises a number to a power (12 ^ 2 = 144) and √ calculates the square root (√144 = 12). The root of a negative number does not exist among the real numbers and returns a warning.
Practical examples
- Discount on a purchase: a product of R$ 250 with a 15% discount. Type
250 − 15%and the result is R$ 212,50. - Rent increase: rent of R$ 1.800 with an 8% raise. Type
1800 + 8%and the result is R$ 1.944. - What is 15% of 200? Type
200 × 15%and the result is 30. - Splitting a bill: R$ 487,60 among 4 people. Type
487,6 ÷ 4and the result is R$ 121,90 per person. - Order of operations:
(8 + 4) × 3 = 36, while8 + 4 × 3 = 20. Use parentheses to control the order. - Side of a square: an area of 81 m². Type
√81and the side measures 9 m.
How to calculate percentages and discounts
Three formulas solve almost everything:
- X% of a value:
value × X ÷ 100. 15% of 200 is200 × 15 ÷ 100 = 30. - Discounted price:
price × (1 − discount ÷ 100). A product of R$ 250 with a 15% discount costs250 × 0,85 = R$ 212,50. - Percentage change:
(new − old) ÷ old × 100. From 80 to 92, the change is(92 − 80) ÷ 80 × 100 = 15%.
To find the original price, divide the final price by (1 − discount): if you paid R$ 85 with a 15% discount, the full price was 85 ÷ 0,85 = R$ 100. Successive discounts do not add up: 10% and then 5% equal 100 × 0,90 × 0,95 = 85,50, that is, 14,5% in total discount, not 15%.
How to calculate simple interest
With simple interest, the return always accrues on the initial amount: J = C × i × t and M = C + J, where C is the principal, i the rate per period and t the number of periods.
Example: R$ 2.000 at 1,5% per month for 6 months. J = 2000 × 0,015 × 6 = R$ 180 and the final amount is R$ 2.180. With compound interest, the same case reaches R$ 2.186,89, because each month earns on the already adjusted balance. To simulate long terms and monthly deposits, use the compound interest calculator.
How to calculate the 13th-month salary by hand
The 13th-month salary (a yearly payment required by Brazilian labor law) equals 1/12 of the salary for each month worked in the year: 13th = salary ÷ 12 × months worked. Someone earning R$ 3.000 who worked 7 months is entitled to 3000 ÷ 12 × 7 = R$ 1.750 gross. A month with 15 days or more of work counts in full.
The 1st installment (50%, with no deductions) is due by November 30 and the 2nd by December 20, already with INSS (the Brazilian social security contribution) and income tax (Imposto de Renda) deducted. To include the deductions for your case, use the 13th-month salary calculator.
How to calculate a financing payment
In the Price table the installments are fixed: PMT = P × i ÷ (1 − (1 + i)^−n). For R$ 100.000 at 1% per month in 12 installments, the payment is R$ 8.884,88 and the total interest is R$ 6.618,55.
In SAC the amortization is constant (P ÷ n) and the interest falls each month: the 1st installment is R$ 9.333,33, the last is R$ 8.416,67 and the total interest is R$ 6.500,00. To see the month-by-month table and compare the two systems, use the SAC and Price financing simulator.
Order of operations
| Priority | Operation | Example |
|---|---|---|
| 1 | Parentheses | (8 + 4) × 3 = 36 |
| 2 | Power and root | 2 + 3 ^ 2 = 11 |
| 3 | Multiplication and division | 8 + 4 × 3 = 20 |
| 4 | Addition and subtraction, from left to right | 10 − 4 + 2 = 8 |
Frequently asked questions
Is the calculator free?
Yes. There is no sign-up and nothing to install, and it works right in the browser, on a computer, tablet or phone.
Are my calculations sent to any server?
No. The calculations are done in your own browser. The history is kept only in your device’s local storage and can be erased at any time with the “Clear history” button.
How do I calculate a percentage?
For “X% of a value”, multiply: value × X%. To apply a discount or a markup, use value − X% or value + X%.
Why does 0,1 + 0,2 show 0,3?
Computers store decimals in binary, which creates tiny differences (such as 0,30000000000000004). The calculator rounds the result to 12 significant digits to display the expected value.
Can I use my computer keyboard?
Yes: numbers, +, -, *, /, (, ), %, ^, comma or dot, Enter to calculate, Backspace to delete and Esc to clear.
How do I calculate the discount on a purchase?
Multiply the price by (1 − discount ÷ 100). For a product of R$ 250 with a 15% discount, the calculation is 250 × 0,85 = R$ 212,50. In the calculator, type 250 − 15% and the result is the same.
What is the difference between simple and compound interest?
With simple interest, interest accrues only on the initial amount. With compound interest, it also accrues on the interest already accumulated. R$ 2.000 at 1,5% per month for 6 months earns R$ 180 in simple interest and R$ 186,89 in compound interest.