Proportion Calculator
Solve a/b = c/d for any missing term.
Amortization schedule
| # | Payment | Principal | Interest | Balance |
|---|---|---|---|---|
Showing first 12 of months.
Growth over time
| Year | Invested | Value |
|---|---|---|
Introduction
Proportion Calculator — Solve a/b = c/d for any missing term. Enter A (leave blank if unknown), B (leave blank if unknown), C (leave blank if unknown), D (leave blank if unknown) to get an instant, accurate result.
Formula
Solves a/b = c/d for whichever single value is left blank, by cross-multiplication.
Step-by-step
- Enter the A (leave blank if unknown).
- Enter the B (leave blank if unknown).
- Enter the C (leave blank if unknown).
- Enter the D (leave blank if unknown).
- Click Calculate to see your result instantly.
Real-world example
Example: With A (leave blank if unknown) = 2, B (leave blank if unknown) = 4, C (leave blank if unknown) = 6, the Proportion Calculator gives Missing: d, Value: 12.
Frequently Asked Questions
How many values do I need to know?
Exactly three — leave the one you want solved for blank.
What is cross-multiplication?
For a/b = c/d, cross-multiplying gives a×d = b×c, which is rearranged to solve for the missing value.
What inputs does the Proportion Calculator need?
You'll need to provide: A (leave blank if unknown), B (leave blank if unknown), C (leave blank if unknown), D (leave blank if unknown). All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Proportion Calculator?
The Proportion Calculator applies the formula exactly as calculated — Solves a/b = c/d for whichever single value is left blank, by cross-multiplication. — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Proportion Calculator free to use?
Yes, the Proportion Calculator is completely free, requires no signup, and runs instantly in your browser.
About the Proportion Calculator
The Proportion Calculator uses a real, verifiable formula — Solves a/b = c/d for whichever single value is left blank, by cross-multiplication. — so results are accurate every time, not an approximation.