Online Calculator
A simple and scientific calculator that replaces the one on your phone or computer: the whole calculation stays visible, the result updates as you type, and your history stays on your device.
- Standard and scientific
- Keyboard and touch
- History and memory
- Free, no sign-up
100% private — Everything is processed directly in your browser: your files, voice, and image are never sent to Chatzam's servers.
How to use the online calculator
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Choose a mode
Standard for everyday math, scientific for trigonometric functions, logarithms, powers and parentheses.
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Type your calculation
Use the on-screen keys or your computer keyboard. The full expression stays visible and a live preview of the result appears below it.
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Press "="
The result is shown large and added to your history. Keep going with an operator to chain calculations, or copy it in one click.
A full-featured calculator in your browser
Correct order of operations
Multiplication before addition, exponents before multiplication, parentheses first: 2 + 3 × 4 correctly gives 14.
Scientific mode
sin, cos, tan and their inverses in degrees or radians, ln, log, roots, powers, factorial, π and e.
History and memory
Every result is saved: one click reuses it or brings back the calculation. M+, M−, MR and MC keys, just like a desk calculator.
Clean results
0.1 + 0.2 shows 0.3, not a long tail of decimals. Very large and very small numbers switch to scientific notation.
Order of operations: how the calculator works things out
The calculator reads the whole expression before computing and applies the rules you learned in school (PEMDAS / BODMAS). Parentheses come first, then exponents, then multiplication and division from left to right, and finally addition and subtraction. So 2 + 3 × 4 = 14, while (2 + 3) × 4 = 20, and 20 − 8 ÷ 4 = 18. A minus sign in front of a power applies after it: −2² = −4, whereas (−2)² = 4. Stacked exponents are evaluated from right to left: 2^3^2 = 2^9 = 512. A number written right next to a parenthesis or π is multiplied: 3(4 + 1) = 15 and 2π ≈ 6.283. Parentheses left open at the end are closed automatically.
Using scientific mode: trigonometry, logarithms and powers
The DEG/RAD button sets the angle unit. In degrees, sin(30) = 0.5, cos(60) = 0.5 and tan(45) = 1; in radians, it's sin(π/6) that equals 0.5. The 2nd key turns sin, cos and tan into their inverse functions (sin⁻¹(0.5) = 30 in degrees) and replaces ln and log with eˣ and 10ˣ. ln is the natural logarithm (ln(e) = 1) and log is the common base-10 logarithm (log(1000) = 3). x² and x³ square and cube a number, xʸ raises it to any power (2^10 = 1024), and √ and ∛ give the square and cube roots. x! computes the factorial of a whole number: 5! = 1 × 2 × 3 × 4 × 5 = 120. 1/x gives the reciprocal and |x| the absolute value.
Percentages, memory, history and precision
The % key works just like on a phone: 200 + 10% = 220 and 200 − 10% = 180, because the percentage applies to the number before it; 50 × 10% = 5; and 10% on its own equals 0.1. The memory keys let you add up results: M+ adds the displayed value, M− subtracts it, MR inserts it back into the calculation and MC clears the memory. The history keeps your last 40 calculations: click a result to insert it, or click the expression to bring it back and edit it. As for precision, computers calculate in binary, which creates tiny rounding errors: the display is rounded to 12 significant digits, so 0.1 + 0.2 gives 0.3 and 1 ÷ 3 × 3 gives 1.
Frequently Asked Questions
How do I calculate a percentage with the calculator?
To add 20% to 150, type 150 + 20%: the result is 180. For a 30% discount on 80, type 80 − 30% = 56. To get 15% of 60, type 60 × 15% = 9.
Why doesn't sin(90) give 1?
The calculator is probably set to radians. Switch to scientific mode and tap DEG/RAD until it reads DEG: sin(90) will then give 1. In radians, a right angle is written π/2.
Can I use my computer keyboard?
Yes: digits, a period or comma for decimals, + − * / ^ ( ) %, ! for factorial, Enter or = to calculate, Backspace to delete the last character and Esc to clear everything.
Why does the calculator show "Error"?
The calculation has no result: division by zero, the square root or logarithm of a negative number, ln(0), tan(90°), sin⁻¹ of a number greater than 1, the factorial of a non-integer, or a result that's too large. A message under the word "Error" explains the cause.
Are my calculations saved anywhere?
Your history and memory are stored only in your browser, on this device, so you can find them on your next visit. Nothing is sent over the internet, and the "Clear history" button deletes them.