Aspect Ratio Calculator: Find Ratios & Resize Dimensions
Enter an image or video width and height to find its aspect ratio, or calculate new pixel dimensions without stretching the original shape. Use common ratio presets or your own custom values.
Find the aspect ratio from width and height
Type the pixel dimensions or choose an image to read its actual width and height locally in your browser.
Select an image file to fill the width and height. The calculator reads it in your browser; it does not upload the file.
1920 × 1080 px · Landscape
Calculate matching width or height
Choose a preset or enter a custom ratio. Type the width or height you want; the other dimension is calculated automatically.
Enter either dimension to calculate the other. Results are rounded to whole pixels; rounding can produce a tiny ratio difference for some sizes.
16:9 · 1280 pixels wide and 720 pixels high
Quick format finder
Select a general format to load a common example size. These are examples, not guaranteed current upload requirements for every platform or placement.
How to calculate an image or video aspect ratio
- Find ratio: Enter a width and height in pixels. The calculator simplifies them to the smallest whole-number ratio when the dimensions are whole numbers.
- Calculate dimensions: Choose a ratio and enter your intended width or height. The calculator fills in the matching other dimension.
- Check your use case: A correct ratio preserves shape, but it does not guarantee a platform accepts that particular pixel size or file format.
Example: 1920 × 1080 simplifies to 16:9. At 1280 pixels wide, a matching 16:9 height is 720 pixels.
Common aspect ratios: practical examples
Example: 1920 × 1080. Common for widescreen video and presentation layouts.
Example: 1080 × 1920. Common for full-height vertical video.
Example: 1080 × 1080. Useful for square graphics and product imagery.
Example: 1080 × 1350. Useful for taller social graphics.
Example: 1000 × 1500. A common tall visual shape.
Example: 1200 × 800. A familiar photo and print ratio.
These are example dimensions, not universal platform requirements. Check the requirements for the exact upload placement before publishing a finished asset.
Aspect ratio vs resolution vs cropping
Aspect ratio describes the relationship between width and height; resolution gives the actual pixel dimensions. For example, 1920 × 1080 and 1280 × 720 are both 16:9, but they have different pixel counts.
If a source image and destination frame have different ratios, maintaining proportions requires either cropping the image, adding space around it, or changing the frame. Changing its width and height independently will stretch it.
Rounding note: A target width may not divide evenly into your chosen ratio. When that happens, the calculator rounds the missing side to the nearest whole pixel and the resulting dimensions may not match the ratio perfectly.
Want to change the actual image file? This calculator does not resize, crop, or upload files. Use the Image Resizer & Converter after calculating your target dimensions.
Continue your design workflow
Apply your new dimensions to an image file.
Create coordinated colors for your next visual.
Make matching CSS backgrounds for layout elements.
Create a QR code for a printed or digital design.
Aspect ratio calculator FAQ
How do I find an aspect ratio from pixel dimensions?
Enter the width and height. The tool divides whole-number pixel dimensions by their greatest common divisor to show a simplified width-to-height ratio.
How do I calculate a matching width or height?
Choose a ratio, then enter either the target width or target height in Calculate dimensions. The missing side is calculated and rounded to a whole pixel.
Does this tool resize or crop my image?
No. It calculates ratios and target pixel dimensions. Use an image editor or the Image Resizer & Converter to change an actual image.
Can I use a custom ratio?
Yes. Change the ratio width and ratio height fields to your own positive values, then enter a target width or height.
Can I find a ratio without knowing my image dimensions?
Yes. Choose an image in the optional local image reader. The calculator fills in its width and height without uploading it to this tool.
Why is the calculated ratio sometimes slightly different?
Images use whole pixels. If the mathematically exact answer is fractional, rounding the missing dimension can introduce a small difference.
Create Better Visuals and Trackable Campaigns
Explore free tools for QR codes, campaign tracking links, structured AI prompts, color palettes, CSS gradients, random colors, and proportional image or video dimensions.
