Ratio Calculator

Ratio Calculator Hub

This page is your all-in-one ratio hub. Enter any two values and get instant outputs for:

• simplified ratio
• decimal ratio
• percentage split
• proportional scaling for width/height

If you only need one specific ratio task, these focused tools are faster:

• Simplify ratio calculator
• Ratio to percentage calculator
• Aspect ratio calculator
• Display ratio calculator
• Proportion calculator (solve equal ratios and missing values)
• Fraction calculator
• Ratio to fraction calculator
• Percentage calculator
• Percentage difference calculator

How to simplify a ratio

To simplify a:b, divide both numbers by their greatest common divisor (GCD).

Example:

• 12:18
• GCD is 6
• simplified ratio is 2:3

Formula:

simplified = (a / gcd(a,b)) : (b / gcd(a,b))

Ratio to decimal and percentage

Given ratio a:b:

• Decimal value of the ratio is a / b
• Percentage split is:
  • first part: a / (a + b) * 100
  • second part: b / (a + b) * 100

Example for 3:2:

• Decimal: 1.5
• Percentage split: 60% / 40%

Scale ratio to new size

When you keep a proportion, one side controls the other.

• New height: newWidth * originalHeight / originalWidth
• New width: newHeight * originalWidth / originalHeight

That is useful for:

• image resizing
• video dimensions
• print/layout scaling
• UI and design work

Common ratio examples

• 16:9 (widescreen video)
• 4:3 (legacy display/photo)
• 3:2 (many camera sensors)
• 1:1 (square social format)

Real-world uses

Ratios show up whenever two or more quantities need to stay in balance. The calculator above handles the numbers; the sections below describe where people search for this idea beyond screen sizes.

Cooking and recipes

Recipes often list ingredients as a ratio—flour to liquid, sugar to butter, spice blends, or dough hydration. If a cake serves four and you need eight, you scale every ingredient by the same factor. If you think in ratios (for example doubling a 2:3 mix of flour to butter), you avoid guessing which ingredients should move together. The same idea applies when you only have half the main ingredient and want to keep flavour balance.

Mixing and construction

Tradespeople work with ratios constantly: concrete mixes quoted as cement : sand : aggregate (such as 1:2:3 by volume), paint tinting (parts of colour to base), two-stroke fuel (oil to petrol), or adhesive hardener ratios. Getting the proportion wrong wastes material or weakens the result, so people search for calculators that make the relationship obvious before they mix.

Maps and scale models

A map scale of 1:50,000 means one unit on the map represents fifty thousand of the same units on the ground. Architectural models use scales like 1:100 or 1:50 so a measurement on the model predicts the built size. Ratios here answer “how long is this in real life?” without confusing units.

Finance (context, not tax advice)

Analysts describe relationships with ratios: debt-to-income compares monthly debt payments to income; price-to-earnings compares share price to earnings per share; the current ratio compares short-term assets to short-term liabilities. These are not “simplify 12:18” problems, but they are the same mental model—one number relative to another—so people land on ratio pages when learning the vocabulary.

Photography and printing

Print sizes (5×7, A-series), sensor crops, and “effective focal length” all rely on comparing dimensions. Designers match artboard ratios to ad specs; photographers keep crop boxes at 4:3 or 3:2 for consistent deliverables. Scaling without skew uses the same multiply- or divide-both-sides logic this tool implements.

FAQ

What is a ratio calculator?

A ratio calculator helps you write two quantities as a simplified ratio, turn them into a decimal or percentage split, and scale both sides to new sizes while keeping the same relationship.

How do I calculate a ratio between two numbers?

Write the two numbers as a:b (or a/b). For example, 10 and 25 become 10:25, which simplifies to 2:5 by dividing both sides by their greatest common divisor.

How do you simplify a ratio?

Find the greatest common divisor of both values, then divide each side by that number until the two sides share no common divisor except 1.

How do I simplify a ratio with large numbers?

Use the same rule as small numbers: divide both sides by their GCD. For very large values, keep dividing by common factors or use a calculator GCD step to avoid manual trial and error.

How do I convert ratio to percentage?

For ratio a:b, the first part is a/(a+b)×100% and the second part is b/(a+b)×100%. Those two percentages add up to 100%.

What is a 3:1 ratio as a percentage?

For 3:1, the total parts are 3+1=4. The first value is 3/4=75% and the second is 1/4=25%.

What is the difference between ratio and proportion?

A ratio compares two quantities in one statement (like 2:3). A proportion states that two ratios are equal (like 2:3 = 4:6). Solving proportions finds a missing value when the relationship stays the same.

What is a ratio in maths?

In maths, a ratio is a multiplicative comparison between two or more numbers. It shows relative size, not necessarily the total—useful for fractions, scaling, similar figures, and rates.

How do I calculate a ratio with 3 numbers?

Write them in order as a:b:c. You can simplify all three by dividing by their greatest common divisor if they share one. For mixing (like concrete), the order matches the recipe columns (cement:sand:aggregate).

Does order matter in a ratio?

Yes. 2:3 is not the same as 3:2—the first number refers to the first quantity and the second to the second.

Can I use decimals in a ratio?

Yes. This calculator accepts decimals and still returns simplified and converted outputs.

Can I copy the result?

Yes. Use the copy controls in the result cards to quickly paste into docs, design specs, or code.