Math problems break down into a manageable set of patterns: ratios, percentages, geometric formulas, statistical measures, equations to solve. Once you can identify which pattern a problem fits, the calculation itself is mechanical — but doing the mechanics by hand is slow and error-prone, especially when the formulas involve powers, roots, or many variables.
These math calculators handle the mechanics so you can focus on setting up the problem correctly. Convert between fractions, decimals, and percentages; calculate area, circumference, or volume from one or two measurements; solve quadratic equations; find mean, median, and standard deviation across a dataset; and work out percentage change over time. Each tool shows the formula used and the worked steps where they help — so the calculator teaches the method, not just the answer.
Numbers
- Scientific Calculator
Advanced calculator with math functions.
- Decimal to Percent Calculator
Easily convert decimals into percentages.
- Fraction to Percent Calculator
Easily convert fractions into percentages.
- Percent Change Calculator
Calculate change between two numbers.
- Rate of Change Calculator
Calculate the average rate of change for two numbers.
- Aspect Ratio Calculator
Find the simplified aspect ratio of any width and height.
- Slope Calculator
Find slope, y-intercept and line equation from two points.
- GCF & LCM Calculator
Greatest common factor and least common multiple.
- Ratio Calculator
Solve, simplify and scale ratios.
- Quadratic Equation Calculator
Solve ax² + bx + c = 0 with the quadratic formula.
- Mean, Median & Mode Calculator
Find the mean, median, mode, and range of a list of numbers.
- Standard Deviation Calculator
Calculate population or sample standard deviation and variance.
Geometry
- Area of a Circle Calculator
Calculate the area of a circle.
- Circumference Calculator
Calculate the circumference of a circle.
- Radius of a Circle Calculator
Calculate the radius of a circle.
- Square Footage Calculator
Find the area of a room or lot in sq ft, sq m, sq yd or sq in.
- Volume Calculator
Calculate the volume of a shape.
- Pythagorean Theorem Calculator
Find any side of a right triangle using a² + b² = c².
FAQs
Divide by 100. 25% becomes 0.25; 7.5% becomes 0.075; 200% becomes 2.0. To go the other direction (decimal to percentage), multiply by 100 and add the % sign.
Mean is the average (sum divided by count). Median is the middle value when the dataset is sorted. Mode is the most frequent value. They differ most when data is skewed — for income or house prices, the median is usually more representative than the mean, because a few very large values pull the mean upward.
Subtract the old value from the new, divide by the old value, then multiply by 100. So going from 80 to 100 is a (100-80)/80 × 100 = 25% increase. Going from 100 to 80 is a 20% decrease — note that a 25% gain followed by a 20% loss returns you to the original, even though the percentages aren't equal.
Area equals π (pi, approximately 3.14159) times the radius squared, written as A = πr². If you have the diameter instead, the radius is half the diameter. For circumference, the formula is C = 2πr, or equivalently π times the diameter.
For any right-angled triangle, the square of the hypotenuse (the longest side, opposite the right angle) equals the sum of the squares of the other two sides — written a² + b² = c². It's used to find an unknown side when the other two are known, and shows up in distance problems, construction, and 2D geometry.