Online Calculator

Decimal places:10

Last updated October 20, 2018

Basic and scientific calculator with history, memory, and keyboard support

Whether you need to add up a grocery bill, check a percentage tip, or work through a trigonometric equation, our free online calculator has you covered. Available instantly in any web browser with no download, no sign-up, and no ads cluttering the interface, it is designed to be the last calculator tool you will ever need to search for. The calculator offers two modes. Basic mode gives you a clean, touch-friendly interface with the standard keys you expect: digits 0 through 9, the four arithmetic operators, plus-minus sign toggle, percentage, memory (MC, MR, M+, M−), backspace, and all-clear. Everything responds instantly to mouse clicks, touch taps, or keyboard input — including the number pad on a full keyboard. Scientific mode expands the keypad with trigonometric functions (sin, cos, tan and their inverses), logarithms (log base 10 and natural log), exponential functions (eˣ, 10ˣ), square root, cube root, general power (xʸ), factorial, absolute value, and the mathematical constants π and e. An Inverse (INV) toggle flips sin/cos/tan into their arc-function counterparts and swaps log with 10ˣ and ln with eˣ for maximum efficiency without screen clutter. Angle mode switching between degrees (DEG) and radians (RAD) ensures that trigonometric calculations produce the correct result for your context. Students working in degrees for geometry class and engineers computing in radians for signal processing both get accurate output without needing to do unit conversion by hand. Calculation history is automatically recorded as you compute. The last ten expressions and their results appear in a scrollable sidebar, each with a one-click Use button that loads the historic result back into the display for chaining into further calculations. The Answer (Ans) key in scientific mode serves the same purpose for the most recent result. You can clear the history at any time with the Reset button. Memory functions provide a running scratch-pad. Press M+ to add the displayed value to memory, M− to subtract it, MR to recall whatever is stored, and MC to clear it. An M indicator lights up on the display bar whenever memory holds a non-zero value. This is indispensable for multi-step calculations where you need to keep a subtotal or an intermediate result separate from the current working value. A precision slider lets you control how many decimal places appear in results — from 0 (integer rounding) up to 10. Set it to 2 for currency calculations, leave it at the default of 10 for scientific work, or dial it to 0 for quick integer estimates. Results that would overflow standard notation are automatically displayed in scientific exponential format (e.g., 1.23e+15) so very large and very small numbers remain readable. Copying a result to the clipboard takes a single click on the Copy icon next to the display. The icon briefly changes to a checkmark to confirm the action. This makes it easy to paste calculated values into spreadsheets, emails, or other applications without retyping. Keyboard users are fully supported. Type digits directly, use + − * / for operators, press Enter or = to evaluate, Backspace to delete the last digit, and Escape to clear everything. The calculator captures keystrokes at the window level, so you do not need to click inside it first — just start typing. All expression evaluation uses a custom Shunting-Yard parser that respects standard mathematical operator precedence (PEMDAS/BODMAS). Multiplication and division are resolved before addition and subtraction, and power operations are right-associative. Division by zero, square root of a negative number, logarithm of a non-positive number, and factorial of a non-integer all produce descriptive error messages rather than silent NaN values, making it easy to spot and correct input mistakes. The layout uses a two-column design on larger screens so the calculator keypad and the result history panel are visible side by side without scrolling. On mobile, both panels stack naturally. The design adapts to light and dark themes automatically, following your device or browser preference.

Understanding the Online Calculator

What Is an Online Calculator?

An online calculator is a software application running in a web browser that replicates the functionality of a physical handheld or desktop calculator. Unlike device-specific apps, a browser-based calculator requires no installation and works identically across Windows, macOS, Linux, iOS, and Android. Basic online calculators handle the four arithmetic operations and common helper functions like percentage and square root. Scientific online calculators extend this to include full trigonometric functions, logarithms, exponential functions, factorial, and mathematical constants such as π and Euler's number e. Our calculator includes both modes in a single tool, switchable with one click.

How Does the Calculator Work?

The calculator uses a Shunting-Yard algorithm — a well-established computer science technique invented by Edsger Dijkstra — to parse and evaluate mathematical expressions safely without relying on JavaScript's eval() function. Inputs are tokenized into numbers, operators, and function names, then re-ordered into Reverse Polish Notation (RPN) according to operator precedence rules. The RPN stack is then evaluated left-to-right to produce the final result. Trigonometric functions internally convert between degrees and radians based on the active angle mode. Results are rounded to the user-configured precision before display using JavaScript's toFixed() method, and numbers exceeding 10^12 are automatically formatted in scientific exponential notation.

Why Use an Online Calculator?

Physical calculators are easy to misplace, run out of battery, or lack the scientific functions you need on a given day. Smartphone calculator apps exist but are buried inside menus and often lack history, memory indicators, or keyboard input. Spreadsheet apps like Excel are powerful but heavy for a quick calculation. An online calculator sits at the intersection: it opens in two seconds in any browser tab, supports keyboard input for rapid entry, preserves a session history so you can retrace your steps, and handles scientific functions without requiring you to own a dedicated scientific calculator. It is the right tool for students checking homework, accountants verifying totals, engineers estimating values, and anyone who needs a quick answer with more capability than phone apps provide.

Limitations to Be Aware Of

Like all JavaScript-based calculators, results are subject to IEEE 754 double-precision floating-point arithmetic. This means some decimal results will carry small rounding artefacts — for example, 0.1 + 0.2 may display as 0.30000000000000004 at maximum precision, though setting precision to 10 or fewer decimal places hides this. The calculator does not support symbolic algebra, equation solving, calculus (derivatives or integrals), complex numbers, or matrix operations. Factorials are limited to integers up to 170 (beyond which the result exceeds JavaScript's maximum finite number). For high-stakes financial calculations, always verify results independently, as this tool is intended for everyday estimation and learning rather than certified accounting or engineering computations.

Calculator Formulas & Operations

Order of Operations (PEMDAS)

Parentheses → Exponents → Multiplication/Division → Addition/Subtraction

Mathematical expressions are evaluated following PEMDAS (or BODMAS) precedence. Parentheses are resolved first, then exponents, then multiplication and division left-to-right, and finally addition and subtraction left-to-right.

Percentage of a Number

Result = Value × (Percentage / 100)

To find a percentage of a number, multiply the value by the percentage divided by 100. For example, 15% of 200 = 200 × 0.15 = 30.

Memory Addition (M+)

Memory = Memory + DisplayValue

The M+ function adds the currently displayed value to the memory register. Use M− to subtract from memory, MR to recall the stored value, and MC to clear memory back to zero.

Scientific Notation

a × 10ⁿ (where 1 ≤ |a| < 10)

Very large or very small numbers are automatically displayed in scientific notation. For example, 123,000,000,000 is shown as 1.23e+11, meaning 1.23 × 10¹¹.

Calculator Reference Tables

Calculator Operations Reference

Complete reference of all basic, scientific, and memory operations available in the calculator.

Operation	Symbol / Key	Example	Result
Addition	+	15 + 7	22
Subtraction	−	20 − 8	12
Multiplication	×	6 × 9	54
Division	÷	45 ÷ 5	9
Percentage	%	200 × 15%	30
Square Root	√	√144	12
Power	xʸ	2^10	1024
Sine	sin	sin(30°)	0.5
Cosine	cos	cos(60°)	0.5
Natural Log	ln	ln(e)	1
Log Base 10	log	log(1000)	3
Factorial	n!	5!	120

Keyboard Shortcuts

Keyboard keys that map directly to calculator functions for faster input.

Key	Function
0–9	Enter digits
+ − * /	Arithmetic operators
Enter or =	Evaluate expression
Backspace	Delete last character
Escape	Clear all (AC)
%	Percentage
( )	Group sub-expressions
.	Decimal point

Worked Examples

Evaluate (15 + 3) × 4 − 12 ÷ 2

A multi-operation expression that requires correct order of operations (PEMDAS).

Resolve parentheses first: 15 + 3 = 18

Perform multiplication: 18 × 4 = 72

Perform division: 12 ÷ 2 = 6

Perform subtraction: 72 − 6 = 66

The final answer is 66.

Chain Percentage Calculations: 20% Tip on a $85 Bill

Calculate a 20% tip on an $85 restaurant bill, then find the total amount.

Enter 85 on the calculator display

Multiply by 20 and press %: 85 × 20% = 17

Press M+ to store the tip ($17) in memory

Enter 85 again and press + then MR then =: 85 + 17 = 102

The tip is $17.00 and the total bill is $102.00.

Compute sin(45°) and Verify with cos(45°)

Use scientific mode to compute trigonometric values in degree mode.

Switch to Scientific mode and ensure DEG is selected

Enter 45 and press sin: sin(45°) = 0.7071067812

Enter 45 and press cos: cos(45°) = 0.7071067812

Both values are equal, confirming sin(45°) = cos(45°) = √2/2

sin(45°) = cos(45°) ≈ 0.7071067812, which equals √2/2.

How to Use This Calculator

Choose Basic or Scientific Mode

Click the Basic / Scientific toggle at the top of the calculator. Basic mode shows the standard arithmetic keypad. Scientific mode adds trig functions, logarithms, exponentials, power operations, factorial, constants π and e, and additional memory controls. You can switch modes at any time without losing your current display value.

Enter Your Expression

Click the number buttons or simply type on your keyboard. Use + − * / for arithmetic, or click the operator buttons. For scientific functions like sin or log, enter the number first, then click the function button. Press the xʸ button to raise a number to a custom power — enter the base, click xʸ, then enter the exponent and press =. Use the INV toggle to access inverse trig functions (sin⁻¹, cos⁻¹, tan⁻¹) and swap log with 10ˣ.

Set Angle Mode and Precision

If you are using trigonometric functions, check whether you need degrees (DEG) or radians (RAD) and click the toggle accordingly. The default is degrees, which is correct for most everyday geometry. Adjust the decimal-places slider below the display to control how many digits appear in the result — set it to 2 for money calculations, 0 for whole-number answers, or leave it at the default 10 for scientific work.

Review History and Copy Results

Every completed calculation is logged in the History panel on the right. Click Use next to any past result to load it back into the display for further calculations — this lets you chain long multi-step problems without writing anything down. Click the Copy icon in the display bar to copy the current result to your clipboard, then paste it wherever you need it. Use the memory keys (M+, MR, MC) to hold a running subtotal across multiple separate calculations.

Frequently Asked Questions

Is this online calculator free to use?

Yes, this calculator is completely free with no sign-up required, no subscription, and no download. It runs entirely in your web browser using JavaScript, so it works on any device — desktop, laptop, tablet, or phone — without installing anything. There are no usage limits; you can perform as many calculations as you like in a single session. The calculation history stores your last ten results for the duration of your browser session, and it is cleared automatically when you close or refresh the page.

Does the calculator follow standard order of operations (PEMDAS)?

Yes. The calculator uses a Shunting-Yard algorithm to evaluate expressions according to standard mathematical operator precedence — often remembered by the acronym PEMDAS (Parentheses, Exponents, Multiplication, Division, Addition, Subtraction) or BODMAS in British English. Multiplication and division are computed before addition and subtraction, and exponentiation is right-associative (so 2^3^2 = 2^9 = 512). When you press an operator button after a previous result, the calculator chains the operations in the correct order automatically.

How do I use the memory functions (M+, MR, MC)?

Memory functions let you store a number and reuse it later without retyping it. Press M+ to add the currently displayed value to memory (the M indicator appears near the display to show memory is active). Press M− to subtract the current value from memory. Press MR to recall whatever is stored in memory and load it into the display. Press MC to clear the memory register back to zero and remove the M indicator. Memory persists across calculations for the entire session, so you can use it as a running subtotal while working through a multi-step problem.

What is the difference between DEG and RAD mode?

DEG (degrees) and RAD (radians) are two units for measuring angles, and the choice affects all trigonometric functions (sin, cos, tan, and their inverses). In degree mode, a full circle is 360°, so sin(90) = 1. In radian mode, a full circle is 2π ≈ 6.283 radians, so sin(π/2) ≈ sin(1.5708) = 1. For everyday geometry, navigation, and most school problems, degrees are the natural choice. For calculus, physics formulas, and engineering signal processing, radians are the standard. The calculator defaults to DEG — switch to RAD by clicking the angle mode toggle when working in scientific contexts.

Why does 0.1 + 0.2 not equal exactly 0.3?

This is a fundamental characteristic of binary floating-point arithmetic, the standard used by virtually all calculators, programming languages, and processors. Decimal fractions like 0.1 and 0.2 cannot be represented exactly in binary, so tiny rounding errors accumulate. Our calculator reduces this by defaulting to 10 decimal places of precision, which hides most visible floating-point noise (0.1 + 0.2 displays as 0.3 at ≤10 decimal places). If you slide precision to the maximum of 10, you may still see 0.30000000000000004 at full precision — this is normal and not a bug. For money calculations, set precision to 2 decimal places.

Can I use the calculator with my keyboard?

Yes, full keyboard input is supported. Type the digit keys 0–9 to enter numbers, use the period key for the decimal point, and press + − * / for arithmetic operators. Press Enter or the = key to evaluate the expression, Backspace to delete the last digit entered, and Escape to clear everything (equivalent to the AC button). The percent key (%) triggers the percentage function. The calculator captures keystrokes at the window level, so you can start typing immediately without clicking inside the calculator first. Number pad keys also work on full keyboards, making rapid data entry fast and comfortable.