In short

What is this page?

The Calc Solver Formulas Reference collects essential equations for algebra, geometry, statistics, and finance in one place — each explained in plain language, with a link to the calculator that solves it.

Every formula names what each variable means

Each formula links directly to a calculator that applies it

No account needed to view or use any formula

Finance

Finance formulas

I = P × r × t

Simple Interest

Interest earned on the original amount only, P principal, r rate, t time.

A = P(1 + r/n)ⁿₜ

Compound Interest

Interest earned on principal plus previously earned interest.

((new − old) / old) × 100

Percentage Change

The percent increase or decrease between two values.

Statistics

Statistics formulas

x̄ = Σx / n

Mean (Average)

Adds all values and divides by how many there are.

σ = √(Σ(x−x̄)² / n)

Standard Deviation

Measures how spread out a data set is from its mean.

P(A) = favorable / total

Probability

The chance of an event, as favorable outcomes over total outcomes.

Geometry

Geometry formulas

A = πr²

Area of a Circle

Finds the space inside a circle, where r is the radius.

a² + b² = c²

Pythagorean Theorem

Finds a missing side of a right triangle, where c is the hypotenuse.

V = (4/3)πr³

Volume of a Sphere

Finds the space inside a sphere, where r is the radius.

Algebra

Algebra formulas

x = (−b ± √(b²−4ac)) / 2a

Quadratic Formula

Solves any quadratic equation of the form ax² + bx + c = 0.

m = (y₂ − y₁) / (x₂ − x₁)

Slope Formula

Finds the slope, or steepness, of a line between two points.

a² − b² = (a+b)(a−b)

Difference of Squares

Factors an expression that is one square subtracted from another.

FAQ

Questions about this reference, answered

The questions people actually ask before using a formula.

Is this formula reference free to use?

Yes. Every formula and its explanation is free, with no account required.

Can I calculate these formulas directly on calc solver?

Yes. Each formula links to the calculator that applies it, so you can plug in your own numbers instead of solving by hand.

Are more formulas added over time?

Yes. New formulas are added as new calculator categories and tools are released.

Do the formulas include worked examples?

The related blog articles and calculators show worked examples. This page focuses on the formula itself and what each variable means.

How are the formulas organized?

Formulas are grouped by category, matching the site's calculator categories, so you can jump straight to the topic you need.

Reference

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