Scientific Calculator

Scientific calculator

Type any maths expression and get the answer instantly. It supports trigonometry, logarithms, square roots, powers, factorials, parentheses, and the constants pi and e — a full replacement for a handheld scientific calculator, right in the browser.

A parser, not an eval

You type a complete expression rather than pressing one button at a time. The input is read by a safe custom parser that respects standard operator precedence (powers before multiplication and division, those before addition and subtraction) and parentheses. It never uses JavaScript eval, so a typo can only produce an error, never run code. A degrees/radians toggle controls how the trig functions interpret their inputs.

Supported tokens:

Example expressions

With the degrees toggle on, entering (3 + 4) * sqrt(16) - log(100) evaluates as 7 × 4 − 2 = 26. Switch to radians and sin(pi / 2) returns 1.

Here are more worked examples — all of these parse correctly in the calculator:

Practical tips

Degrees vs radians. Switch the toggle before entering trig expressions — this is the single most common source of wrong answers. In degrees, sin(90) is 1; in radians, sin(90) is approximately 0.894 (because 90 radians is not a right angle).

Order of operations. The parser follows standard BODMAS/PEMDAS. Powers are evaluated first, then multiplication and division, then addition and subtraction. Use parentheses liberally when in doubt: 2 + 3 * 4 is 14, while (2 + 3) * 4 is 20.

Factorial limits. Very large factorials like 50! produce numbers with many digits that may display in scientific notation or overflow standard floating-point precision. Results up to around 20! (about 2.4 × 10^18) are exact; beyond that, expect floating-point rounding.

Chaining functions. You can nest functions freely: sqrt(abs(-16)) is valid and returns 4. The parser handles any depth of nesting as long as brackets are balanced.

Degrees and radians: the conversion in your head

The two units measure the same angles on different scales: a full circle is 360° or 2π radians, so 1 radian ≈ 57.2958° and radians = degrees × π/180. The anchor values worth memorising:

Mathematics, physics and programming libraries default to radians (JavaScript’s own Math.sin takes radians only); surveying, navigation and everyday problems use degrees. If an answer looks wildly wrong, the toggle is the first thing to check.

Why some results show a tiny error

Like virtually every computer and handheld calculator, this tool computes with IEEE 754 double-precision floating point — the binary number format documented in MDN’s Number reference. Doubles — specified by the IEEE 754 standard — carry about 15–17 significant decimal digits, and some decimal values (famously 0.1) have no exact binary representation, which is why 0.1 + 0.2 computes internally to 0.30000000000000004. Consequences you may notice:

• Results are trustworthy to ~15 significant digits; digits beyond that are noise.
• sin(pi) in radians returns a value like 1.2e-16 rather than exactly 0 — that is zero to machine precision.
• Integers are exact up to 2⁵³ (about 9 × 10¹⁵); factorials beyond 18! cross that line and round.

None of this is a bug in any particular calculator — it is the arithmetic all mainstream hardware uses, and knowing the ~15-digit limit tells you exactly how far to trust any digital calculation.

Typing expressions faster

A few input habits that save time: multiplication accepts both * and ×, and division accepts / and ÷, so you can type entirely from the keyboard. Constants compose naturally with operators — 2*pi*6371 gives Earth’s circumference in kilometres from its radius. Inverse trig results respect the degrees toggle, so atan(1) reads 45 in degrees mode and 0.7853… (π/4) in radians. And because the whole expression is visible at once, you can edit any part of it and re-evaluate instantly — the main workflow advantage over a button-at-a-time handheld.

Everything runs locally in your browser, so nothing you type is uploaded.