How to determine aspect ratio using just dimensions

Steps:

1. Enter your width dimension
2. Enter your height dimension
3. Click "Calculate"
4. Get your aspect ratio instantly

What You Get:

• Simplified ratio (16:9)
• Decimal form (1.78:1)
• Visual representation
• Practical information

Example:

• Input: 1920 width, 1080 height
• Result: 16:9 (or 1.78:1)
• Takes 5 seconds

Basic Formula:

Aspect Ratio = Width ÷ Height

Step 1: Get your dimensions

Example: 1920 × 1080

Step 2: Divide width by height

1920 ÷ 1080 = 1.777...

This gives you the decimal form (1.78:1 rounded)

Step 3: Find the Greatest Common Divisor (GCD)

To simplify 1920 and 1080:

• GCD of 1920 and 1080 = 120

Step 4: Divide both by the GCD

• Width: 1920 ÷ 120 = 16
• Height: 1080 ÷ 120 = 9

Step 5: Express as ratio

Result: 16:9

Example 1: Simple Dimensions

• Dimensions: 800 × 600
• Divide: 800 ÷ 600 = 1.33
• GCD: 200
• 800 ÷ 200 = 4
• 600 ÷ 200 = 3
• Result: 4:3

Example 2: Square

• Dimensions: 1000 × 1000
• Divide: 1000 ÷ 1000 = 1
• Both equal, so divide each by themselves
• Result: 1:1

Example 3: Portrait

• Dimensions: 1080 × 1350
• Divide: 1080 ÷ 1350 = 0.8
• GCD: 90
• 1080 ÷ 90 = 12
• 1350 ÷ 90 = 15
• Result: 4:5 (or 12:15 simplified further)

Memorizing these saves time:

• 16:9 - Widescreen (common)
• 4:3 - Standard (older)
• 1:1 - Square
• 21:9 - Ultrawide
• 16:10 - Monitor standard
• 4:5 - Portrait/Instagram
• 9:16 - Vertical video
• 3:2 - Photography

16:9 example:

• For every 16 units of width
• There are 9 units of height
• This proportion stays constant
• Whether 1920×1080 or 3840×2160

4:5 example:

• For every 4 units of width
• There are 5 units of height
• Results in portrait orientation
• Used for Instagram posts

If GCD isn't obvious, use this method:

1. Divide larger by smaller
2. Take remainder
3. Divide previous by remainder
4. Repeat until remainder = 0
5. Last divisor is the GCD

Example: GCD of 1920 and 1080

• 1920 ÷ 1080 = 1 remainder 840
• 1080 ÷ 840 = 1 remainder 240
• 840 ÷ 240 = 3 remainder 120
• 240 ÷ 120 = 2 remainder 0
• GCD = 120

Check your ratio by multiplying back:

• Ratio: 16:9
• Multiply by any number: 16×100 = 1600, 9×100 = 900
• You should get a valid dimension pair

Divide the first number by second:

• 16 ÷ 9 = 1.78 (or 1.78:1)
• 4 ÷ 3 = 1.33 (or 1.33:1)
• 21 ÷ 9 = 2.33 (or 2.33:1)

Use the calculator if:

• You need quick results
• You're not confident in math
• You need multiple formats
• You have many dimensions

Use manual math if:

• You want to learn how it works
• You're teaching someone
• You need to understand the concept

Use recognition if:

• You see a common dimension
• You know standard ratios
• You need instant answers

• ❌Mistake 1: Putting height before width

- Always: Width ÷ Height (NOT Height ÷ Width)

- Wrong: 1080 ÷ 1920 = 0.56

- Correct: 1920 ÷ 1080 = 1.78

• ❌Mistake 2: Forgetting to simplify

- 1920:1080 is correct but not simplified

- 16:9 is the standard form

- Always reduce to lowest terms

• ❌Mistake 3: Confusing aspect ratio with resolution

- Resolution = exact pixels (1920×1080)

- Aspect ratio = proportion (16:9)

- Different resolutions can have same ratio