Formula Calculator

A multi-line, reactive formula calculator for engineers, students, and developers. Write calculations like code: define variables, evaluate expressions, and watch every dependent line update instantly. It runs entirely in your browser — no installation, no server, your formulas never leave your device.

Assign a variable with name = value, then reuse it on later lines:

price = 199 count = 3 tax = 0.08 total = price * count * (1 + tax)

A line without an = sign is treated as a bare expression and its result is shown on the right. Variables accumulate as you go down, so each line can reference anything defined above it.

• Comments: start a line with // or append // … at the end of a line. • SI prefixes: append a prefix to a number — 10k, 4.7u, 100n, 2.2M, 5p — and it expands automatically. When a line uses an SI prefix, its result is also shown with a prefix. • Implicit multiplication: a number directly followed by a name becomes multiplication — 2PI becomes 2*PI, and 10kOhm becomes 10*1000*Ohm. • Spaces inside a line are ignored, so you can format freely.

All common math functions are available: sin, cos, tan, asin, acos, atan, atan2, sinh, cosh, tanh, sqrt, cbrt, pow, exp, log, log2, log10, abs, round, floor, ceil, sign, trunc, gcd, lcm, factorial, max, min, and more. Constants include pi, e, phi, and tau (uppercase PI and E are also accepted). Click any chip in the Functions panel to insert it at the cursor.

• Real-time evaluation — results update on every keystroke. • Per-line results panel aligned with your code. • Syntax highlighting with matched-bracket highlighting. • Live variable snapshot you can copy as JSON. • Automatic save to your browser — reload and keep working. • Works offline once the page is loaded.

1. Quick engineering math with units (resistors, capacitors, RC time constants). 2. Breaking a long calculation into readable, reusable steps. 3. Exploring formulas interactively by tweaking variables. 4. Checking homework or verifying spreadsheet logic.