Ratio Calculator
Everything ratios: Solve for X, simplify to lowest terms, or scale up/down for recipes and screens.
Ready to Calculate
Enter your values on the left to specific ratio calculations instantly.
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Mastering the Art of Ratios
A ratio is simply a relationship between two numbers indicating how many times the first number contains the second. Whether you are cooking a meal, mixing concrete, or designing a website, getting the ratio right is the key to balance and harmony. This tool handles the math so you can focus on the result.
3 Ways to Use This Tool
1. Solve (Find X)
The "Rule of Three". If you know 3 numbers, you can find the 4th. "If 1 cup of rice needs 2 cups of water, how much water for 5 cups of rice?"
2. Simplify
Turn big, unwieldy numbers into clean ratios. Convert 1920:1080 into the classic 16:9 automatically.
3. Scale
Resize an entire project. Double a recipe, shrink an image, or expand a floor plan while keeping the proportions identical.
The Magic Number: 1.618 (Phi)
The Golden Ratio (φ) is famous for appearing everywhere in nature, from the spirals of galaxies to the center of sunflowers. It is mathematically unique and visually balanced.
Ratios in the Real World
Cooking
Vinaigrette is a classic 3:1 ratio of oil to vinegar. Perfect rice is usually 2:1 water to rice.
Photography
Cameras shoot in 3:2 (DSLR) or 4:3 (iPhone). Movies are often ultra-wide 2.35:1.
Construction
Concrete mix is often remembered as 1:2:3 (Cement : Sand : Aggregate).
Frequently Asked Questions
How do you solve a ratio for X?
To solve A:B = C:X, you use the 'Cross-Multiplication' method. Multiply the two known diagonal numbers (B × C) and divide by the remaining number (A). Formula: X = (B × C) / A.
What is the Golden Ratio?
The Golden Ratio (represented by the Greek letter Phi, φ) is approximately 1.618. It is a mathematical ratio found in nature (shells, flowers) and art that is considered aesthetically perfect. Our calculator can help you scale designs to this ratio.
How do I simplify a ratio?
To simplify a ratio like 10:20, find the Greatest Common Divisor (GCD) of both numbers. The GCD of 10 and 20 is 10. Divide both sides by 10 to get the simplified ratio of 1:2.
What is an Aspect Ratio?
An aspect ratio describes the relationship between the width and height of an image or screen. Common ratios are 16:9 (Widescreen TV) and 4:3 (Old monitors). If you know the width, you can use a ratio calculator to find the matching height.
Can ratios have decimals?
Yes, but they are usually converted to whole numbers for clarity. For example, 1.5 : 3 is mathematically valid, but we typically multiply both sides by 2 to write it as the cleaner whole-number ratio of 3 : 6 (or 1 : 2 simplified).
How do I scale recipes?
Use the 'Scale' mode. If a recipe calls for 2 cups of flour for every 3 eggs (2:3), and you want to use 9 eggs, enter 2:3 on one side and put '9' in the egg slot on the other side. The calculator will tell you to use 6 cups of flour.
What is the differences between Part-to-Part and Part-to-Whole?
In a class of 10 boys and 20 girls: The 'Part-to-Part' ratio of boys to girls is 10:20 (1:2). The 'Part-to-Whole' ratio of boys to students is 10:30 (1:3).
Is a ratio the same as a fraction?
Almost. A ratio compares two quantities (apples to oranges), while a fraction compares a part to a whole (apples to total fruit). However, mathematically, a ratio a:b can often be written as the fraction a/b.