Basic Calculator
A free, fast basic calculator for everyday arithmetic — add, subtract, multiply, divide and percentages.
About this calculator
The basic calculator is the everyday, no-frills tool for quick arithmetic. Tap the buttons or use your keyboard to add, subtract, multiply and divide, work out percentages, or flip a number’s sign — it works instantly on any device with no sign-up. This is the plain four-function calculator most people reach for day to day. For trigonometry, logarithms, powers and roots, use the scientific calculator; for a mortgage or budget, see the finance calculators instead.
It behaves like a classic pocket calculator: you enter a number, choose an operator, enter the next number, and it evaluates left to right as you go, showing a running total on the display. The equals key finishes the current calculation, the percent key turns the current entry into a percentage of that running total, the sign key flips positive to negative, and the clear key resets everything. Everything responds to the keyboard too, so you can type as fast as you think.
For a worked example, keying 200 + 10 % gives 220, because the percent key reads 10 % as 10% of 200 (that is 20) and adds it on; keying 50 × 3 − 20 = returns 130. Reach for it to split a bill, add up a shopping list, work out a discount or tip, or do any of the quick sums that come up through the day without opening a spreadsheet.
Frequently asked questions
How does this calculator work?
Enter numbers and operators with the on-screen buttons or your keyboard. It calculates left to right as you go, like a standard pocket calculator, and shows the running total. Press = for the final result and C to clear.
Can I use my keyboard?
Yes. The number keys, + − * / for operators, Enter or = to calculate, Backspace to delete, and Escape to clear all work.
What is the % key for?
The percent key converts the current number to a percentage of the running total — for example 200 + 10 % gives 220 (10% of 200 added on).
How do I calculate a tip or a discount?
For a 15% tip on 40, key 40 + 15 % to get 46. For a 20% discount, key 50 − 20 % to get 40. The percent key treats the entry as a percentage of the running total.
Why does 2 + 3 × 4 give 20 on this basic calculator?
Because it evaluates left to right as each key is pressed, so 2 + 3 makes 5 and then × 4 makes 20, rather than doing the multiplication first. For strict order-of-operations precedence use the scientific calculator, which parses the whole expression at once.
How do I clear the calculator or fix a mistake?
Press C (or Escape on the keyboard) to clear everything and start over, and Backspace to delete the last digit you entered without wiping the whole sum.
What does the ± sign key do?
It flips the sign of the number on the display, turning a positive value negative or a negative value positive — handy for subtracting or entering a negative amount.
Results are estimates for general guidance only, not financial, medical or tax advice.