Math & Statistics Calculators
Arithmetic, algebra, geometry, statistics and probability, with exact arithmetic where it matters and the method shown.
Arithmetic & Algebra
Calculators, percentages, fractions, ratios, powers and logs, quadratics and linear systems.
- Basic Calculator
Arithmetic with keyboard input, exact decimals and clear operator precedence.
- Scientific Calculator
Trig, logs, powers and roots in degrees or radians with visible precedence.
- Percentage Calculator
Percent of a number, reverse percentages and percentage change.
- Fraction Calculator
Exact fraction arithmetic with simplification and mixed numbers.
- Ratio and Proportion Calculator
Simplify ratios, solve proportions for a missing value and scale ratios.
- Exponent, Root and Logarithm Calculator
Powers, nth roots and logarithms in any base with domain checks.
- Quadratic Equation Solver
Real, repeated or complex roots of ax² + bx + c = 0, with the discriminant and vertex.
- System of Linear Equations Solver
Solve 2×2 and 3×3 systems and detect singular or inconsistent systems.
Geometry
Triangles, circles, plane shapes, solids and coordinate geometry.
- Triangle Calculator
Solve a triangle from SSS, SAS, ASA, AAS or SSA, including the ambiguous case.
- Circle Calculator
Radius, diameter, circumference and area from any one of them.
- Area and Perimeter Calculator
Rectangle, square, parallelogram, trapezoid and ellipse area and perimeter.
- Volume and Surface Area Calculator
Cube, cuboid, cylinder, sphere, cone and pyramid volume and surface area.
- Slope, Distance and Midpoint Calculator
Slope, line equation, distance and midpoint between two points.
Statistics & Probability
Summary statistics, spread, weighted averages, counting, probability and distributions.
- Mean, Median and Mode Calculator
Mean, median, mode, range and quartiles for a data list, with the quartile method stated.
- Standard Deviation Calculator
Sample or population variance and standard deviation, step by step.
- Weighted Average Calculator
Average of values with weights, such as grades or blended rates.
- Permutation and Combination Calculator
Exact counts of arrangements and selections, with or without repetition.
- Probability Calculator
And, or, not and conditional probability for independent or dependent events.
- Binomial Distribution Calculator
Exact and cumulative binomial probabilities with the full distribution table.
- Normal Distribution and Z-Score Calculator
Normal probabilities, z-scores and percentiles, with accuracy limits stated.
Related guides
- Common percentage mistakes and how to avoid them
Six percentage slips that produce confident wrong answers, from percentage points to negative starting values, each worked with example numbers you can check.
- Mean, median or mode? How to choose a summary statistic
How to pick the center and spread that describe your data fairly, with worked numbers and a side-by-side of the quartile rules that different tools use.
- How to measure a room for square footage and volume
Measure, convert inches to decimal feet, split odd shapes into rectangles, then multiply and convert with a squared or cubed factor. Worked with an L-shaped room, a concrete pad and a water tank.
- Solving triangles: which rule to use, and the SSA ambiguous case
A table for choosing the law of sines or the law of cosines, a worked SSA example with two valid answers, and the step-order and rounding traps that make hand-solved triangles go wrong.
- Unit conversion pitfalls: gallons, tons, cups, GB vs. GiB
Nine unit traps with the numbers worked out: US vs. imperial gallons and pints, fluid ounces vs. ounces, three kinds of ton, cups of flour in grams, cup and tablespoon sizes, GB vs. GiB, bits vs. bytes, temperature changes and UK vs. US mpg.
- How much extra flooring, tile, paint and concrete to buy
Published rules of thumb for overage by material and layout, what each one covers, and worked examples that apply the allowance first and round up to whole boxes, cans and bags last.