Basic Calculator
A full-screen calculator for everyday addition, subtraction, multiplication, and division.
About this calculator
How This Calculator Works
A straightforward calculator for everyday arithmetic — addition, subtraction, multiplication, and division — with a scientific mode toggle for trigonometry, logarithms, powers, and more, right in your browser with no ads in the way.
Standard Mode Keys
The percent key converts the current number to a hundredth of itself (useful mid-calculation for tip or discount math). The plus/minus key flips the sign of the current number. The backspace key deletes the last digit you typed, so a typo doesn't force you to clear the whole entry and start over — and holding it down deletes repeatedly.
Scientific Mode
Switching on Scientific mode adds trigonometric functions (sine, cosine, tangent, with a degrees/radians toggle), logarithms (base-10 and natural log), powers and roots, a reciprocal function, the constants π and e, and factorial. Like the standard keypad, operations are applied sequentially in the order you press them, the same way a physical calculator works, rather than following full algebraic order of operations.
Worked example
Like a physical calculator, operations chain left to right as you enter them rather than following algebraic order of operations: 6 + 4 = 10, then pressing × 3 multiplies that running total, giving 30 — not the 18 you'd get by calculating 4 × 3 first.
Frequently asked questions
Does this follow order of operations (PEMDAS)?
No — like most physical calculators, it evaluates left to right as you press keys. Entering 2 + 3 × 4 gives (2+3)×4 = 20, not the algebraic 14.
What does the % key do?
It divides the current display value by 100 in place, so you can chain it into a running calculation — useful for quick percentage math like tips or discounts.
Why does dividing by zero show an error?
Division by zero is undefined, so the calculator shows an error state instead of a number rather than silently returning something misleading.
Can I use my keyboard instead of clicking?
Yes — number keys, +, -, *, /, Enter (=), and Backspace all work directly, matching the on-screen buttons.