Ratio Calculator
Calculate the ratio between two numbers, simplify ratios, and convert to decimal form with our free online ratio calculator.
Ratio Solver
Provide any three values to calculate the fourth in the ratio A:B = C:D.
Ratio Scaling Calculator
Scale a ratio by a factor to get new values while maintaining the same proportion.
Visual Representations of the Ratio
Convert Ratio to Fraction
A part-to-part ratio states the proportion of the parts in relation to each other. The sum of the parts makes up the whole. The ratio 1 : 2 is read as "1 to 2." This means of the whole of 3, there is a part worth 1 and another part worth 2.
To convert a part-to-part ratio to fractions:
- Add the ratio terms to get the whole. Use this as the denominator.1 : 2 => 1 + 2 = 3
- Convert the ratio into fractions. Each ratio term becomes a numerator in a fraction.1 : 2 => 1/3, 2/3
- Therefore, in the part-to-part ratio 1 : 2, 1 is 1/3 of the whole and 2 is 2/3 of the whole.
Converting Ratios to Percentages
To convert a ratio to a percentage, you first convert it to a fraction and then multiply by 100.
Example: Convert the ratio 3 : 4 to a percentage
- First, determine what part of the whole you want to express as a percentage. Let's say we want to know what percentage 3 is of the total (3+4).
- Calculate the fraction: 3 ÷ (3+4) = 3 ÷ 7 = 0.4285...
- Multiply by 100 to get the percentage: 0.4285... × 100 = 42.85%
Therefore, in the ratio 3 : 4, the first part represents approximately 42.85% of the whole.
Converting Ratios to Decimals
To convert a ratio to a decimal, divide the first number by the second number.
Example: Convert the ratio 3 : 4 to a decimal
3 ÷ 4 = 0.75
The ratio 3 : 4 as a decimal is 0.75, which means the first number is 0.75 times the second number.
Equivalent Ratios
Equivalent ratios are ratios that express the same relationship between numbers. You can find equivalent ratios by multiplying or dividing both terms of the ratio by the same number.
Example: Find equivalent ratios for 3 : 4
- Multiply both terms by 2: 3 × 2 : 4 × 2 = 6 : 8
- Multiply both terms by 5: 3 × 5 : 4 × 5 = 15 : 20
- Multiply both terms by 25: 3 × 25 : 4 × 25 = 75 : 100
All of these ratios (3:4, 6:8, 15:20, 75:100) are equivalent because they represent the same proportional relationship.
Typical Aspect Ratios and Sizes of Screens and Videos
The aspect ratio is the ratio of a geometric shape's sizes in different dimensions. In the case of a rectangle, the aspect ratio is that of its width to its height. Below is a list of typical computer screen/video resolutions and aspect ratios.
| Name | Aspect ratio | Width (pixel) | Height (pixel) |
|---|---|---|---|
| 480p | 3:2 | 720 | 480 |
| 576p | 5:4 | 720 | 576 |
| 720p | 16:9 | 1280 | 720 |
| 1080p | 16:9 | 1920 | 1080 |
| 1440p | 16:9 | 2560 | 1440 |
| 4K UHD | 16:9 | 3840 | 2160 |
| Cinema 4K | 17:9 | 4096 | 2160 |
| 8K UHD | 16:9 | 7680 | 4320 |
Common Ratio Applications
Ratios are used in many fields from photography to design, architecture, and media production. Here are some common ratio applications you might encounter.
| Name | Ratio | Description |
|---|---|---|
| Standard Photo | 3:2 | Common in DSLR photography |
| Square Photo | 1:1 | Instagram classic format |
| Widescreen TV | 16:9 | Modern television standard |
| Ultrawide Monitor | 21:9 | Cinematic computer displays |
| Classic Cinema | 4:3 | Traditional film and early TV |
| Cinemascope | 2.35:1 | Widescreen cinema format |
| Golden Ratio | 1:1.618 | Aesthetically pleasing proportion |
What is a Ratio?
A ratio is a comparison between two or more related numbers, indicating how many times one value contains or is contained within the other. It expresses the relationship between quantities and can be written in different forms such as 3:1, 3/1, or as a decimal 3.0.
How to Calculate Ratios
To calculate a ratio, follow these steps: 1) Choose two numbers you want to compare, 2) Write them with a colon between them (e.g., 3:1), 3) Simplify if possible by dividing both numbers by their greatest common divisor, 4) Convert to decimal form by dividing the first number by the second number.
Common Ratio Examples
- Recipe ingredients: 2 cups of flour to 1 cup of sugar (2:1 ratio)
- Map scale: 1 inch represents 100 miles (1:100 ratio)
- Financial planning: Spending to saving ratio of 4:1