Scientific & Programmable Calculator

How to Create Custom Formulas

Open the "🧩 Formulas" tab and tap "+ New Formula" to build a reusable expression out of variables, constants, and functions — like Ohm's Law, V = I × R. Save it under a name, then run it again and again with different inputs by typing that name into the display and pressing =. Variables you store are shared everywhere on this calculator, so a value you calculate on the keypad can feed straight into a formula. 19 ready-made formulas — covering geometry, physics, finance, and everyday conversions — are already loaded in the Formulas panel the first time you open this calculator; see the worked examples below for exactly how each one runs.

Step 1: Create a Variable

A variable is just a name paired with a number, and it's the building block every formula is made of. Tap the "📦 Variables" tab, then the "+" button. Type a name — letters, numbers, and underscores only, and it has to start with a letter, so rate1 works but 1rate doesn't — and confirm it. The display then asks for the variable's value: type a number (or any expression, like 5+3), and press "=" to store it. From that point on, typing that name anywhere on the keypad, or referencing it inside a formula, pulls in whatever value is currently saved. Re-saving a variable with the same name overwrites its old value everywhere it's used.

Step 2: Create a Formula

Tap the "🧩 Formulas" tab, then "+". Name the formula the same way as a variable (letters/numbers/underscore, starting with a letter), then the display switches into formula-building mode. Type the expression using the keypad's operators and function buttons (sin, cos, ln, √, ^, and so on) plus any variable names the formula needs as bare words — you don't have to create those variables ahead of time, since running the formula later will simply ask for each one's value if it isn't already saved. When the expression is complete, tap "Save." The calculator checks the syntax immediately and refuses to save anything invalid, so a formula in the list is always guaranteed to run.

Step 3: Run a Formula

There are two ways to run a saved formula. The quickest is from the Formulas list itself: tap the "⋮" menu next to any formula and choose "Run" — the calculator walks through every variable the formula needs, one prompt at a time ("Enter a value for 'radius':"), and shows the result the moment the last one is confirmed. The second way is to tap the formula in the list to insert its reference into the display (it appears as fm{Name}), then press "=" — useful when you want to combine a formula with other math in the same expression, like doubling its result or adding it to another value. Either way, if a variable the formula needs already has a saved value, the calculator uses it automatically instead of asking again (toggle "Use stored variable values" in the Variables panel to turn this behavior off if you'd rather be prompted every time).

19 Ready-Made Formulas to Get You Started

These are pre-loaded in the Formulas panel the first time you open this calculator in a browser, so there's nothing to build before running them — they're also a good reference for the exact syntax the parser expects. Turn "Use default formulas" off (next to the search box) to hide all 19 and see only your own.

Deleting any (or all 19) of these is permanent for that browser — they were a one-time starting point, not something that keeps re-appearing after you've cleared them.

Composing Formulas — Building on Other Formulas

Formulas can reference other saved formulas by name, so you can build small pieces and combine them into larger ones without repeating the math. Saving blocks any reference that would create a circular dependency, so a formula can never depend on itself.

How to Use an Online Scientific Calculator

Click the buttons or type directly with your keyboard to build an expression, then press = (or Enter) to evaluate it. Function buttons like sin, log, and √ automatically open a parenthesis — type your number and close it yourself, or just keep typing and the calculator will guide you. Every result you calculate is saved to the History panel automatically; click any of them to reuse it.

Trigonometric Functions Explained — Sin, Cos, Tan

Sine, cosine, and tangent describe the ratios between a right triangle's sides relative to one of its angles. Sin(angle) is the ratio of the opposite side to the hypotenuse, cos(angle) is the adjacent side to the hypotenuse, and tan(angle) is the opposite side to the adjacent side. Their inverses — sin⁻¹, cos⁻¹, tan⁻¹ — work backward: given a ratio, they tell you the angle that produced it.

Logarithms — Natural vs. Common

A logarithm answers "what power do I need to raise this base to, to get this number?" The common logarithm (log) uses base 10: $\log_{10}(1000) = 3$, because $10^3 = 1000$. The natural logarithm (ln) uses base $e$ (≈2.71828), which appears naturally in continuous growth and decay processes, calculus, and compound interest formulas.

Calculating Factorials

$$n! = n \times (n-1) \times (n-2) \times \cdots \times 1$$

For example, $5! = 5 \times 4 \times 3 \times 2 \times 1 = 120$. Type the number and press the n! button, or type ! directly after a number.

Degrees vs. Radians — When to Use Each

Degrees split a full circle into 360 equal parts and are the everyday unit most people learn first. Radians measure angles by arc length relative to the radius, making a full circle equal to 2π radians (~6.283) — this is the unit calculus and most programming languages use internally because it simplifies derivative and integral formulas. Use the DEG/RAD toggle above to match whatever unit your problem is given in.

A Brief History of the Scientific Calculator

Before electronic calculators, scientists and engineers relied on slide rules and printed logarithm tables to compute trigonometric functions, logarithms, and roots by hand — a slide rule remained standard engineering equipment well into the 1970s. The first pocket-sized scientific calculator, the HP-35, was released by Hewlett-Packard in 1972, and it was revolutionary specifically because it brought trigonometric and logarithmic functions — previously the domain of slide rules and bulky desktop machines — into something that fit in a shirt pocket. Texas Instruments followed shortly after with its own scientific calculator lines, and by the late 1970s, affordable scientific calculators had largely displaced the slide rule in classrooms and engineering offices worldwide, marking one of the fastest technology transitions of the era.

Common Scientific Calculator Mistakes

Leaving the calculator in the wrong angle mode is by far the most common error — computing sin(30) in radians instead of degrees gives a completely different (and usually nonsensical-looking) result, since 30 radians is many full rotations around the circle. Confusing log and ln is another frequent mix-up, particularly since many science and engineering formulas specifically call for the natural logarithm, not the base-10 common logarithm. Forgetting order of operations when typing a long expression directly — especially around exponents and nested functions — can also silently produce a wrong answer that looks plausible at a glance.

Scientific Calculator Terms You Should Know

Radian — the standard unit of angle measurement in mathematics, defined so that a full circle equals 2π radians.

Logarithm — the inverse operation of exponentiation, answering "what power gives this result."

Euler's Number (e) — an irrational constant, approximately 2.71828, that arises naturally in continuous growth, decay, and compound interest, and is the base of the natural logarithm.

Factorial — the product of a whole number and every positive whole number below it, used heavily in probability and combinatorics.