Ratio Calculator

Ratio calculator to simplify ratios and scale A:B into real numbers

A ratio compares two quantities by showing how much of one thing there is relative to another. You see ratios everywhere: mixing concentrate with water, splitting a bill, blending ingredients, scaling a recipe, allocating a budget across departments, or converting “parts” into actual measurements. This ratio calculator helps you do three practical jobs quickly: simplify a ratio (reduce it to the smallest clean form), convert a ratio into percentages, and scale a ratio into real values when you know one side or the total.

Start by entering the two ratio parts, A and B. For example, if a mix is 3 parts water to 2 parts syrup, you would enter A = 3 and B = 2. The calculator will show the split as a percentage (A as a share of the total, and B as the remainder). It will also show a normalized version of the ratio, where the smaller side becomes 1. This is useful when the ratio is not a neat pair of integers or when you are comparing ratios that use different numbers but represent the same relationship.

If you want actual numbers rather than “parts,” pick what you know: the real value of A, the real value of B, or the total (A + B). For example, if the ratio is 3:2 and you know A is 150, then the calculator scales B to match the same relationship. If you know the total is 1,000, it will split that total into A and B according to the ratio. This makes ratios directly usable for planning, purchasing, and portioning.

Assumptions and how to use this calculator

• Both ratio parts must be greater than 0. A ratio like 0:5 is not meaningful for proportional scaling.
• Ratio parts can be decimals, but “simple” reduced ratios only apply cleanly when both parts are whole numbers.
• If you enter a known value for A, B, or total, it is treated as a positive real-world quantity in the same unit (money, grams, liters, minutes, etc.).
• Percentages are based on A + B as the total. The calculator assumes A and B are the only two parts being compared.
• Results are rounded to 2 decimals for readability. Small rounding differences can occur, especially when totals must split into repeating decimals.

Common questions

What does it mean to “simplify” a ratio?

Simplifying a ratio means reducing both sides by the same factor so the relationship stays the same but the numbers get smaller. For example, 10:15 simplifies to 2:3. This is easiest when both numbers are whole numbers. If you enter decimals, the calculator will still show a normalized ratio (smallest side becomes 1), which is often the more practical way to compare relationships.

How do I scale a ratio if I only know the total amount?

Choose “I know the total (A + B)” and enter the total. The calculator splits the total into two parts based on each side’s share of A + B. For example, with 3:2 and a total of 1,000, A is 3/5 of the total and B is 2/5 of the total. This is the quickest way to allocate a total budget or mixture amount across two components.

Can I use this for recipe scaling and mixing liquids?

Yes. Ratios are unit-agnostic. If your ratio is 1:4 and you know you want 250 ml of the first ingredient, choose “I know the real value of A” and enter 250. The output for B will be the matching amount in the same unit. The same logic works for grams, liters, cups, or any consistent unit.

What if my ratio parts are not whole numbers?

That can still be valid, especially for measured systems or converted data. In those cases, the “reduced ratio” may not be a neat pair of integers, but the normalized ratio and the percentage split remain accurate. If you want a cleaner ratio, consider multiplying both sides by a common factor to eliminate decimals before using the calculator.

Why do the results sometimes not add up perfectly to the total?

When totals split into repeating decimals, rounding to 2 decimals can cause a small difference (for example, 333.33 + 666.67 equals 1,000.00, but other splits might produce 999.99 or 1,000.01 after rounding). If you need exact accounting, use the unrounded values conceptually and apply rounding rules consistently in your own context.