Aspect Ratio Calculator
Calculate aspect ratio from width and height, find missing dimension, or simplify a ratio.
Find Ratio (W:H)
Find Missing Dimension
Simplify Ratio
px in cm
px in cm
Common Aspect Ratios
Aspect Ratio
16:9
Width: 1920 px, Height: 1080 px
Simplified Fraction
16/9
Decimal (W/H)
1.77778
Height if Width = 1
0.5625
Aspect Ratio Formulas
Aspect Ratio = W : H
Simplified = W/gcd(W,H) : H/gcd(W,H)
Missing dimension = (Known × Ratio) / Other
gcd – greatest common divisor
For a given ratio W:H, if you know width, height = width × H/W
If you know height, width = height × W/H
For a given ratio W:H, if you know width, height = width × H/W
If you know height, width = height × W/H
People Also Ask
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🎬 How to choose the right aspect ratio for video?
📱 How to calculate missing dimension while keeping aspect ratio?
Understanding Aspect Ratio
Aspect ratio is the proportional relationship between the width and height of an image, video, or screen. It is expressed as two numbers separated by a colon (e.g., 16:9). A 16:9 rectangle means that for every 16 units of width, there are 9 units of height.
Why It Matters
Maintaining the correct aspect ratio prevents stretching or cropping when displaying content. It is critical in video production, graphic design, web development, and photography.
Common Resolutions & Aspect Ratios
| Resolution | Width (px) | Height (px) | Aspect Ratio |
|---|---|---|---|
| SD (480p) | 720 | 480 | 3:2 |
| HD (720p) | 1280 | 720 | 16:9 |
| Full HD (1080p) | 1920 | 1080 | 16:9 |
| 4K UHD | 3840 | 2160 | 16:9 |
| Cinema 2K | 2048 | 1080 | ≈1.90:1 |
| Cinema 4K | 4096 | 2160 | ≈1.90:1 |
| iPad (4:3) | 2048 | 1536 | 4:3 |
Detailed FAQs
How do I simplify a ratio like 1920:1080?
Find the greatest common divisor (GCD) of both numbers. For 1920 and 1080, GCD = 120. Divide both by 120 → 16:9. Our calculator does this automatically.
What does a decimal aspect ratio mean?
It is width divided by height. For 16:9, decimal = 16/9 ≈ 1.7778. For vertical orientation (9:16), decimal = 9/16 = 0.5625. This number indicates how many times wider (or taller) the image is.