Results
3:5 = x:20 or splitting 120 by 2:3.How it's calculated
- Enter a ratio such as
3:5. - Compute to simplify the ratio, solve a proportion, or show the percent relationship with steps.
For teaching use only—always check classroom examples before sharing them in assessments.
Teacher notes
- Ask students to name whether the setup is part-to-part or part-to-whole before computing.
- Keep units consistent on both sides of a proportion.
- Use share links only after the displayed steps match the classroom notation.
How to use this calculator effectively
Use this page to simplify ratios, solve proportions, and convert between ratios, fractions, and percentages with visible steps.
How it works
The calculator cross-multiplies proportions and reduces ratios with common factors. Keep all quantities in the same unit before solving so the result represents the intended comparison.
When to use
Use it for recipe scaling, map or drawing scale, mixture checks, classroom proportion problems, and quick percentage conversions.
Common mistakes to avoid
- Comparing values that use different units without converting first.
- Flipping part-to-whole and part-to-part ratios.
- Rounding a ratio before solving the proportion.
- Changing both sides of a proportion at once when debugging a setup.
Interpretation and worked example
For 3:5 = x:20, the tool cross-multiplies 5x = 60 and solves x = 12. If the answer direction feels wrong, check which side represents the same category.
See also
FAQ
How do I simplify a ratio such as 12:18?
For integer terms, divide each term by the greatest common divisor of all the terms. If any terms are decimals, first multiply every term by the same power of 10 until all terms are integers, then reduce in the same way. For example, divide both terms in 12:18 by 6 to get 2:3.
How do I solve a proportion such as 3:5 = x:20?
Cross-multiply: 3 × 20 = 5x, so 60 = 5x and x = 12.
What is the difference between a ratio and a proportion?
A ratio compares two or more quantities, such as 2:3. A proportion states that two ratios are equal, such as 2:3 = 4:6.
Do the order and units of the values matter?
Yes. A:B is generally different from B:A, so keep the same order throughout. When comparing quantities of the same kind, convert them to the same unit first.
How do teacher mode and sharing tools help classroom work?
Teacher mode keeps the worked steps visible for projection or screenshots, LaTeX export supports formal notes, and the share button copies a URL with all inputs so students can revisit exactly the same example.
- Percentage Calculator Convert parts, whole, and percentages instantly.
- Fraction Simplifier Reduce fractions and view Euclidean steps.