Calculator
Generated Table and Exports
Submit the form to create a live proportion table for export.
Plotly Graph
Example Data Table
| Example | Units | Cost | Ratio |
|---|---|---|---|
| Notebook packs | 2 | 10 | 5 per unit |
| Notebook packs | 4 | 20 | 5 per unit |
| Notebook packs | 6 | 30 | 5 per unit |
| Notebook packs | 8 | 40 | 5 per unit |
This example shows a constant direct proportion where cost rises at the same rate as quantity.
Formula Used
In direct proportion, both variables move together at a fixed rate. If one value doubles, the other also doubles. The calculator first finds the constant k, then uses it to solve the missing value, produce a table, and draw the line.
How to Use This Calculator
- Choose whether you want to solve Y, solve X, or find the constant.
- Enter one known proportional pair using X₁ and Y₁.
- Add the target X₂ or target Y₂ based on your selected mode.
- Set graph range, point count, labels, and decimal precision.
- Press Calculate to show the result above the form.
- Review the table, chart, and equation for verification.
- Use the export buttons to save the generated table as CSV or PDF.
Frequently Asked Questions
1. What is direct proportion?
Direct proportion means two variables change together at a constant ratio. When one value increases by a factor, the other increases by the same factor.
2. How do I know whether a relationship is directly proportional?
Check whether y divided by x stays constant for all valid pairs. If the ratio changes, the relationship is not a direct proportion.
3. What does the constant k represent?
The constant k is the rate linking both variables in the equation y = kx. It tells how much Y changes per one unit of X.
4. Can this calculator solve for either variable?
Yes. You can solve for a missing Y using a target X, solve for a missing X using a target Y, or only calculate k.
5. Why does the graph form a straight line?
A direct proportion follows the equation y = kx. That equation always produces a straight line passing through the origin when plotted.
6. What happens if X₁ equals zero?
The calculator blocks that case because k = y/x would be undefined. You need a nonzero known X value to establish the ratio safely.
7. Can I use decimals and negative numbers?
Yes. The calculator accepts decimal and negative values as long as the known X value is not zero and the proportion remains meaningful.
8. What do the CSV and PDF downloads include?
They export the generated table based on your current calculation settings. This makes it easier to review, share, or store proportion results.