doomath Calculator
Ratio & Proportion Calculator
Solve and scale ratios interactively.
InputsChange a value to recalculate instantly
ResultUpdates as you type
FORMULA & STEPSRatio & Proportion Calculator — Mathematical Derivation & Steps
2 StepsSequential Calculation Breakdown
1
Set up proportion
The fourth value is solved by cross multiplication.
2
Solve X
Divide the cross product by A.
λ DooMathWork with this calculation
Local · deterministic · optionalQuick mathNatural-language-style shortcuts for deterministic arithmetic.
Calculator guide
How to use the Ratio & Proportion Calculator
Solve and scale ratios interactively.
01Set inputsChoose values, units and assumptions.
02Apply the modelUse the stated mathematical relationship.
03Read the resultCheck the output against the assumptions before using it.
What this calculator does
Solve and scale ratios interactively.
Formula & method
The result is calculated from the inputs and assumptions shown in the calculator.
Assumptions & notes
Review the inputs, units and assumptions before using the result for a real decision.