โ Math
Proportion Calculator
A proportion states that two ratios are equal. Given three of the four values, cross multiplication gives the fourth โ a calculation used constantly in scaling recipes, drawings and unit rates.
How it works
A
B
C
Missing value D
A รท B
C รท D
Frequently asked questions
How do I use the Proportion Calculator?
Fill in the fields above โ the result recalculates instantly as you type. Everything runs in your browser, so the values you enter are never collected or stored.
Is this calculator free?
Yes. It is completely free, requires no account, and works on phones, tablets and desktops.