Quirkulator

Percentage Calculators

20 calculators covering percentages, change and reverse percentages, each with its formula and worked examples.

Percentage Calculators brings together 20 calculators for percentages, change and reverse percentages, including Decimal to Fraction Calculator, Golden Ratio Calculator, Percentage Difference Calculator and Proportion Solver.

These are separate pages rather than one tool with a mode switch because the inputs differ, the interpretation differs, and the question behind each one is different. Each page opens with the formula it uses, defines every variable, and walks the calculation through real numbers before you type anything.

All 20 pages compute in your browser: nothing you type is sent anywhere, and results update as you edit. Each one carries worked examples, interpretation bands where a score needs context, and a FAQ answering what people actually ask about that calculation.

The collection is part of Math & Statistics, and every page links to the neighbouring calculations you usually need next.

20 pages in this collection

Decimal to Fraction CalculatorTurn a decimal into its simplest exact fraction using continued fractions.Dilution Ratio CalculatorWork out how much concentrate and water a given dilution ratio requires.Fraction to Decimal CalculatorDivide a numerator by a denominator and see whether the decimal terminates or recurs.Fraction to Percent CalculatorConvert a fraction straight to a percentage, with the decimal and the complement.Golden Ratio CalculatorSplit a length in the golden proportion, or extend one into a golden rectangle.Percent Change Between Two NumbersMeasure the change from an old value to a new one as a signed percentage.Percentage CalculatorFind any percentage of any number, with the remainder and the one-percent unit.Percentage Decrease CalculatorTake a percentage off a value and see what remains, plus the rise needed to undo it.Percentage Difference CalculatorCompare two values symmetrically, using their average as the base.Percentage Error CalculatorCompare a measured value with the accepted one and size the error in relative terms.Percentage Increase CalculatorAdd a percentage to a starting value and see the new total and the amount added.Percentage Points CalculatorSeparate the percentage-point gap between two rates from the relative change.Proportion SolverSolve a : b = c : x for the missing fourth term by cross multiplication.Ratio Simplifier CalculatorReduce a two-part ratio to its lowest whole-number terms.Ratio to Fraction CalculatorConvert a part-to-part ratio into part-to-whole fractions and percentages.Ratio to Percentage CalculatorTurn a two-part ratio into each side's percentage share of the whole.Reverse Percentage CalculatorRecover the original value from a figure that has already been changed.Scale Factor CalculatorConvert between model and real dimensions, including area and volume scaling.Three Way Ratio Split CalculatorDivide any amount between three parties in a given ratio.What Percent Is X of Y CalculatorExpress one number as a percentage of another, with the ratio and the shortfall.

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