Math calculator
Proportion Calculator
Solve proportions using cross multiplication.
How the calculation works
In a:b = c:d, solve for d using cross multiplication: d = (b × c) ÷ a.
Example: If 2:5 = 4:x, then x = 10.
Important limitations
This tool provides a mathematical estimate based only on the values entered. It does not account for regulations, taxes, lender fees, medical circumstances, structural requirements, or other project-specific factors unless explicitly stated.
Frequently asked questions
How accurate is the proportion calculator?+
The calculation follows the displayed formula and retains full numeric precision before formatting the result.
Can I use the result professionally?+
Use it as a planning estimate. Confirm regulated, medical, financial, or construction decisions with a qualified professional.