Proportion Calculator
This calculator helps you solve proportions of the form a : b = c : x and find the unknown value.
Understanding Proportions
A proportion states that two ratios are equal:
a : b = c : x
To find the unknown value x, use the formula:
x = (b × c) / a
Example: If 3 : 4 = 6 : x → x = (4 × 6) / 3 = 8
How the Calculator Works
The calculator automatically:
Step 1: Takes input values: a, b, c
Step 2: Checks that a is not zero
Step 3: Applies the formula x = (b × c) / a
Step 4: Displays the result instantly
Examples
1. 3 : 4 = 6 : x → x = (4×6)/3 = 8
2. 5 : 8 = 10 : x → x = (8×10)/5 = 16
3. 7 : 2 = 21 : x → x = (2×21)/7 = 6
4. 9 : 12 = 15 : x → x = (12×15)/9 = 20
Why Proportions Matter
Proportions are widely used in real life for recipes, scaling, map reading, finance, and problem-solving in mathematics.
Common Mistakes to Avoid
- Swapping a and b incorrectly
- Forgetting to multiply before dividing
- Using inconsistent units
Important: Keep the order consistent: a corresponds to c, b corresponds to x.
Correct: x = (b × c) / a, not (a × c) / b.
Frequently Asked Questions
Can values be decimals?
Yes. a, b, and c can be decimals.
What if a = 0?
a cannot be zero, as division by zero is undefined.
Can this work for fractions?
Yes. Simply enter fractional values as decimals or simplified numbers.
Conclusion
This proportion calculator is a simple tool to quickly find unknown values in proportional relationships, making it easier for students, teachers, and professionals to solve ratio and proportion problems efficiently.