What is an Online Calculator?
An online calculator is a web-based tool that lets you perform mathematical calculations directly in your browser without installing any software. This calculator supports two modes: a simple mode for everyday arithmetic (addition, subtraction, multiplication, division) and a scientific mode for advanced operations including trigonometry, logarithms, exponents, factorials, and more.
Unlike desktop calculator apps, this tool runs entirely in your browser using JavaScript. No data is sent to any server, making it fast, private, and available anywhere you have internet access. It uses a safe expression parser instead ofeval(), ensuring security while supporting complex mathematical expressions.
Calculator Modes
| Mode | Operations | Best For |
|---|---|---|
| Simple | +, -, ×, ÷, % | Everyday math, quick calculations |
| Scientific | sin, cos, tan, log, ln, √, x², x^y, n!, |x| | STEM, engineering, advanced math |
Keyboard Shortcuts
You can use your keyboard for faster input. The calculator responds to the following keys:
| Key | Action |
|---|---|
| 0-9 | Enter digits |
| . (period) | Decimal point |
| + - * / | Arithmetic operators |
| ^ (caret) | Exponentiation |
| ( ) | Parentheses |
| Enter or = | Evaluate expression |
| Backspace | Delete last character |
| Escape | Clear all |
| % | Convert to percentage |
Common Formulas Reference
| Formula | Expression | Description |
|---|---|---|
| Pythagorean theorem | sqrt(a^2 + b^2) | Length of hypotenuse |
| Circle area | π * r^2 | Area of a circle with radius r |
| Compound interest | P * (1 + r)^n | Future value of investment |
| Quadratic formula | (-b ± sqrt(b^2 - 4*a*c)) / (2*a) | Roots of ax² + bx + c = 0 |
| Distance formula | sqrt((x2-x1)^2 + (y2-y1)^2) | Distance between two points |
| Euler's identity | e^(π*i) + 1 = 0 | Fundamental mathematical identity |
Frequently Asked Questions
Yes. This calculator runs 100% in your browser using JavaScript. No data is sent to any server. The expression parser is built from scratch using a shunting-yard algorithm — it does not use JavaScript's eval() function, which means there is no risk of code injection.
Simple mode provides basic arithmetic operations: addition, subtraction, multiplication, division, and percentage. Scientific mode adds advanced functions including trigonometric functions (sin, cos, tan), logarithms (ln, log), square root, exponentiation, factorial, absolute value, modulo, and mathematical constants (π and e).
The trigonometric functions (sin, cos, tan) use radians, which is the standard unit in mathematics and programming. To convert degrees to radians, multiply by π/180. For example, sin(90°) would be entered as sin(π/2) or sin(1.5708).
Yes. You can use parentheses to control the order of operations. For example, (2+3)*4 equals 20, while 2+3*4 equals 14. In scientific mode, parentheses buttons are available on the keypad. You can also type them directly using your keyboard.
The calculator uses JavaScript's native number type, which can represent values up to approximately 1.8 × 10^308. For factorial calculations, the maximum input is 170! — beyond that the result exceeds the representable range and returns Infinity.
Yes. You can type numbers (0-9), operators (+, -, *, /), decimal points, parentheses, and the caret (^) for exponentiation. Press Enter or = to evaluate, Backspace to delete the last character, and Escape to clear the entire expression.
Every time you press = to evaluate an expression, the calculation is added to the history displayed above the current result. The history shows your last 10 calculations. History is stored in memory and will be cleared when you refresh the page.
An 'Error' result typically means the expression is mathematically invalid. Common causes include division by zero, taking the square root of a negative number, factorial of a negative or non-integer number, logarithm of a non-positive number, or mismatched parentheses. Check your expression and try again.
Yes. The calculator is fully responsive and works on mobile devices. The button layout is optimized for touch input with appropriately sized tap targets. You can use it in portrait or landscape orientation on any modern smartphone or tablet.