🖩 Basic Calculator
A clean, fast basic calculator for everyday math. Add, subtract, multiply, divide, use percentages and toggle signs — all running locally in your browser.
What is this tool?
A basic calculator is a tool for performing the four fundamental arithmetic operations — addition, subtraction, multiplication and division — along with a few everyday helpers such as percentages and sign toggling. It is the kind of calculator most people reach for when splitting a bill, working out a discount, or double-checking a quick sum, and it is far faster to open in a browser tab than to hunt for a physical device. This calculator mimics the simple, button-driven layout popularised by phone and desktop calculators. You enter numbers and operators with on-screen buttons (or your keyboard), see the running expression as you type, and press equals to evaluate the result. A percentage key converts a value into its percentage form on the fly, and a plus/minus key flips the sign of the current entry without retyping it. A backspace key lets you correct mistakes one digit at a time instead of clearing everything. Because every calculation happens entirely in your browser using JavaScript, nothing is sent to a server and your numbers never leave your device. That makes this tool suitable for sensitive figures such as salary estimates, loan down payments, or expense totals. There is no history stored between visits, so each session starts fresh and private.How it works
The calculator evaluates arithmetic expressions using a safe, local algorithm rather than the risky eval() function. Internally it builds a small list of numbers and operators as you press buttons, then walks through the list in two passes: first it resolves all multiplication and division (which have higher precedence), then it resolves addition and subtraction left to right. This guarantees that an expression like 2 + 3 × 4 returns 14, not 20, exactly as standard math rules require. The percentage key multiplies the current value by 0.01 so that pressing 50 % turns 50 into 0.5, letting you compute things like 200 × 15 % × the original amount in a natural way. The sign toggle simply multiplies the current entry by -1. The backspace key trims the last character of the current entry. Only digits, a single decimal point, and the four operators are ever accepted as input, so malformed expressions are prevented before they can cause an error.How to use
- Tap the number buttons (or use your keyboard) to enter the first value.
- Press an operator button such as +, −, ×, or ÷.
- Enter the second value; chain as many operations as you need.
- Use % to convert a value to a percentage, or +/− to flip its sign.
- Press = to see the result; press C to clear and start a new calculation.
Frequently Asked Questions
Frequently Asked Questions
Does this calculator follow the correct order of operations?
Yes. Multiplication and division are always evaluated before addition and subtraction, so 2 + 3 × 4 equals 14. This matches standard mathematical precedence and the behaviour of most phone and scientific calculators.
Can I use my keyboard instead of the buttons?
Yes. Number keys, the four operators, the decimal point, Enter (equals) and Backspace all work. Typing is often faster than clicking, and both input methods stay perfectly in sync.
Is my calculation history saved?
No. The calculator keeps no persistent history, so nothing is stored after you close or refresh the page. Every visit starts with a clean screen, which also protects the privacy of any sensitive numbers you enter.
What does the percentage button actually do?
The % key converts the current entry into its decimal percentage form by multiplying it by 0.01, so 15 becomes 0.15. This lets you naturally compute a portion of an amount, for example 200 × 15 % to find 15 percent of 200.
Tips & Advice
For multi-step problems, chain your operations without pressing equals after every step — the calculator holds the running total and applies operator precedence correctly, so 10 + 5 × 2 gives 20 rather than 30. Use the percentage key as a multiplier: to add 8 percent tax to 50, type 50 + 50 × 8 % and press equals. The backspace key is your friend for correcting a single mistyped digit without starting over. If a result looks unexpectedly large or small, check that you have not accidentally toggled a sign with the +/− key. Because everything runs locally, you can safely use this calculator for private figures such as salary or budget numbers — nothing is ever transmitted or stored.