Aspect Ratio Calculator
Enter the original width and height of an image or video, then enter your desired output height to find the proportionally scaled width. Maintains the correct aspect ratio for responsive design, video editing, printing, and social media cropping.
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Formula
Output Width = Original Width × (Target Height ÷ Original Height)
The aspect ratio is original_width divided by original_height. Multiplying the target height by this ratio gives the proportionally correct output width. This preserves the width-to-height relationship exactly. For example, 1920×1080 has a ratio of 1.778:1 (16:9). At 720 pixels tall, the correct width is 1280 pixels.
How to use the Aspect Ratio Calculator
- 1
Enter your original width (px)
- 2
Enter your original height (px)
- 3
Enter your target height (px)
- 4
Read your results instantly
Results update in real time as you type.
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Common Aspect Ratios
Standard aspect ratios: 16:9 (1.778) is the dominant widescreen format for HD/4K video and most monitors; 4:3 (1.333) is the legacy TV and presentation format; 1:1 (1.0) is square, used extensively on Instagram; 9:16 (0.5625) is vertical video for TikTok and Instagram Reels; 2:1 (2.0) is used for cinema and some ultra-wide displays; 3:2 (1.5) is the standard DSLR photo format. Knowing your target aspect ratio helps you crop and resize correctly for each platform.
Responsive Design and Image Scaling
In web development, maintaining aspect ratios prevents image distortion across screen sizes. CSS property aspect-ratio handles this automatically in modern browsers, but knowing the mathematical relationship is useful when working with explicit pixel dimensions in design tools, video editors, and print layouts. This calculator works for any unit — pixels, inches, millimeters — as long as both dimensions use the same unit.
Tips & Insights
Find Both Dimensions
To find scaled height from a target width instead, swap the inputs: enter target width in the target_height field, and enter the original dimensions in reverse (height as width and vice versa).
Use for Print Sizing
This works with inches and centimeters too. A 4×6 inch photo scaled to 3 inches tall: output width = 4 × (3/6) = 2 inches.
Check Common Social Media Specs
Instagram post: 1080×1080 (1:1). YouTube thumbnail: 1280×720 (16:9). LinkedIn banner: 1584×396 (4:1). Twitter/X header: 1500×500 (3:1). Use this calculator to resize any source to these targets.
Worked Examples
1080p to 720p (16:9)
Output width: 1280 px. Ratio: 1.78:1.
4:3 Photo Scaled Down
Output width: 800 px. Ratio: 1.33:1.
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Frequently Asked Questions
What is aspect ratio?
Aspect ratio is the proportional relationship between width and height. 16:9 means for every 16 units of width there are 9 units of height. It is often expressed as a decimal (1.778) or ratio (16:9).
How do I scale by width instead of height?
Use the formula: Output Height = Original Height × (Target Width ÷ Original Width). Alternatively, swap the inputs in this calculator by treating target width as if it were a target height.
What aspect ratio is 1920×1080?
1920 ÷ 1080 = 1.778, which is 16:9. This is the standard HD and 4K widescreen aspect ratio.
How do I crop without distortion?
Cropping changes the aspect ratio. To crop without distortion, crop equal amounts from both sides (left+right, or top+bottom) to maintain the original ratio, or choose a new target ratio and crop accordingly.
Can I use this for non-pixel units?
Yes. Enter inches, centimeters, or any consistent unit. The math is the same regardless of units — what matters is the proportional relationship.
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