Math Calculators

What the math calculators cover

The math category holds seventeen calculators for the arithmetic that comes up at a desk, in a classroom, or halfway through a project: quick sums, percentages, unit conversions, triangle geometry, algebra, statistics, number-base conversions, and small utilities. They are deliberately separate rather than bundled into one overloaded tool, so each one is fast to load and obvious to use.

Everyday arithmetic

• Basic calculator — add, subtract, multiply, divide, and take percentages, with full keyboard support.
• Percentage calculator — the three distinct questions behind the word “percent”: X% of Y, X as a percent of Y, and percent change.
• Ratio calculator — simplify ratios, solve proportions, and scale one side to match another.

Geometry

• Pythagorean theorem — any side of a right triangle from the other two, with a scaled drawing and the area.

Converting between systems

• Unit converter — length, weight, volume, speed, data, and temperature across metric and imperial.
• Number base converter — binary, octal, decimal, and hexadecimal.
• Roman numeral converter — convert to and from Roman numerals, including subtractive notation.
• Scientific notation — switch between standard and scientific form, and read the exponent correctly.

Algebra, functions, and combinatorics

• Quadratic solver — roots of ax² + bx + c, using the discriminant to show whether they are real, repeated, or complex.
• Logarithm calculator — logs in any base, including the natural log and base 10.
• LCM and GCD — least common multiple and greatest common divisor for a set of numbers.
• Factorials, permutations, combinations — n!, nPr, and nCr for counting problems and probability.

Statistics

• Mean, median, mode and standard deviation — central tendency and spread from one pasted list of numbers.

Utilities

• Age calculator — exact age in years, months, and days from a date of birth.
• Random number generator — random integers in a range, unique or repeatable (0–1 gives a coin flip).

When should I use which math tool?

Start with the shape of the question. If it needs a running calculation, the basic calculator is a scratch pad. If it involves a share or a change, use the percentage calculator rather than doing it by hand — it separates the three percentage questions that people routinely mix up. If the numbers are in different units, convert first so you are comparing like with like. Geometry, algebra, and statistics each have a dedicated tool because their formulas are easy to mis-apply under time pressure.

Common mistakes

• Converting, then mixing systems again. Convert once, write the result down, and stay in one system for the rest of the calculation.
• Confusing percent change with percentage points. A move from 5% to 6% is one point but a 20% change; the percentage calculator keeps the two apart.
• Rounding mid-calculation. Round only at the end, or small errors compound into visible ones.
• Squaring before converting units. Area and volume scale by the square or cube of a length conversion, which catches people out. In the Pythagorean tool, both legs must be in the same unit before squaring.
• Using a mean on skewed data. When a data set has outliers, the median describes it better than the average.

Frequently asked questions

Do I need to install anything?

No. Every tool runs in the browser on the page itself, so there is nothing to download and no account to create. Inputs are written into the page URL so a calculation can be bookmarked or shared.

Are the formulas shown?

Most tools display the formula they applied alongside the answer, and the explainer on each page gives a worked example. That way you can check the logic rather than trusting a black box.

Which tool should I use for a word problem?

Identify the operation first: a share or change is a percentage; a comparison across units needs the converter; a right triangle is the Pythagorean tool; a spread of values is the standard deviation. Pick the operation, then the tool.

Math tools do double duty across the site. The same arithmetic behind a percentage becomes a discount in the finance calculators, a macro split in the health calculators, or a quote in the home and construction calculators.