Ratio Calculator
Use this tool to simplify a ratio, view percentage comparisons, generate an equivalent ratio, and optionally split a total amount using the same ratio.
What is a ratio?
A ratio compares two quantities. If you write 2:3, you are saying the first amount has 2 parts while the second has 3 parts. Ratios are everywhere: recipes, finance, maps, classroom data, construction plans, and business metrics.
A good “calculator of ratio” helps you do four core things quickly:
- Simplify values to their cleanest form (like 12:18 to 2:3).
- Scale to create equivalent ratios (2:3 to 4:6, 20:30, and so on).
- Compare one side as a percentage of the other.
- Distribute totals fairly based on ratio parts.
How this ratio calculator works
1) Simplifying the ratio
The calculator converts your two numbers into whole-number parts and divides both by their greatest common divisor (GCD). That produces the simplest form without changing the relationship.
Example: for 45 and 60, the GCD is 15. Divide both sides by 15 and you get 3:4.
2) Equivalent ratio using a scale factor
If you enter a scale factor, the calculator multiplies both simplified parts by the same number. This keeps the proportion unchanged.
Example: simplified ratio 3:4 with scale factor 5 becomes 15:20.
3) Percentage relationships
The tool also shows how A compares to B and how B compares to A in percentage terms. This is useful in budgeting, growth analysis, and score comparisons.
4) Splitting a total amount by ratio
If you provide a total, the calculator divides that total according to your ratio parts. For ratio A:B and total T:
- A share = T × A / (A + B)
- B share = T × B / (A + B)
Practical use cases
Budget planning
Suppose you want to split income between savings and expenses in a 3:7 ratio. The calculator instantly gives exact amounts for any paycheck size.
Recipe scaling
If ingredients are in a ratio (for example flour:water = 5:3), you can maintain taste and texture while increasing or decreasing batch size.
Workload balancing
Need to assign tasks to two teams based on capacity? Use a ratio like 4:5 and split the total number of tasks fairly.
Data and analytics
Ratios help compare conversion rates, user segments, ad spend allocation, and many other business metrics. Simplified ratios are also easier to communicate to stakeholders.
Common mistakes to avoid
- Using different units before comparing (e.g., meters vs. centimeters). Convert first.
- Forgetting to simplify, which can hide clear patterns.
- Changing only one side when scaling an equivalent ratio.
- Ignoring zero constraints (a ratio of 0:0 is undefined and invalid).
Quick examples
Example 1: Simplify
Input A = 24, B = 36 → simplified ratio is 2:3.
Example 2: Equivalent ratio
Input A = 8, B = 12, scale factor = 2.5 → simplified 2:3, equivalent 5:7.5.
Example 3: Split total
Input A = 3, B = 2, total = 500 → A gets 300, B gets 200.
Final thoughts
A reliable ratio calculator saves time and prevents arithmetic errors. Whether you are working on finance, education, nutrition, engineering, or productivity planning, ratio fluency is a small skill with a big payoff. Use the calculator above, then sanity-check your result by asking one question: Did both sides change proportionally?