Math Calculators
Percentages, ratios, fractions, probability and statistics. Every page prints the formula it used and names the mistake people actually make with it.
- Percentage CalculatorEnter a percentage and a number to see the amount, plus the totals with it added and removed.
- Percentage Change CalculatorEnter the starting value and the new value to see how much it changed, in percent.
- Percentage Difference CalculatorEnter two values to compare them without either one being treated as the starting point.
- Fraction to Decimal CalculatorEnter a numerator and a denominator to see the decimal, the percentage and the simplest form.
- Ratio CalculatorEnter two quantities to see the ratio reduced, split as percentages and expressed as 1 to n.
- Rule of Three CalculatorIf A corresponds to B, what corresponds to C? Both proportions are solved at once.
- Reverse Percentage CalculatorYou have the number after the change. This finds the one before it.
- Circle CalculatorEnter a radius. Everything else about the circle follows from it.
- Triangle Area CalculatorTwo ways to the same answer, depending on which measurements you actually have.
- Probability CalculatorEnter the probability of each event to see how they combine.
- Bayes Theorem CalculatorEnter how common the condition is and how the test performs to see what a positive result really implies.
- Combination CalculatorEnter how many items there are and how many you take to see the combinations and permutations.
- Z-Score CalculatorEnter a value with the mean and standard deviation of its distribution.
- Confidence Interval CalculatorEnter your sample mean, standard deviation and size to see the interval around it.
- Sample Size CalculatorEnter the margin of error you want and the size of the group you are studying.
- Average CalculatorPaste or type your numbers, separated by spaces, commas or line breaks.