Aspect Ratio Calculator
Enter width and height to find the aspect ratio, preview the frame, resize dimensions, or detect an uploaded image locally in your browser.
Aspect ratio tool
Find ratio and resize.
Popular ratios
Visual preview
Find aspect ratio
Enter dimensions
Aspect ratio
16:9
Decimal
1.7778
Common name
16:9 HD
Resize by ratio
Calculated size
1280 x 720
More aspect ratio presets
The most common ratios are already above the preview. Use this extended list for screens, print crops, banners, and ultrawide layouts.
Detect from image
Drop in a JPG, PNG, WebP, or GIF to read real image dimensions. The file stays on your device.
Quick references
Ratio presets
See the shape before you export.
A ratio is easier to choose when you can see the frame. These common formats cover most image, video, social, screen, and design workflows.
Widescreen video
1920 x 1080Use for YouTube, TVs, slides, webinars, product demos, and most horizontal video exports.
Vertical shorts
1080 x 1920Use for TikTok, Instagram Reels, YouTube Shorts, phone-first ads, and story-style media.
Portrait social post
1080 x 1350A strong choice for feed images because it gives more vertical space without becoming a story.
Square creative
1080 x 1080Useful for avatars, thumbnails, marketplace cards, grid previews, and balanced social posts.
Practical guide
Resize images and videos without distortion.
Use this calculator when you need exact dimensions, a simplified ratio, a visual preview, or a CSS value. It is built for creators, designers, editors, developers, and anyone preparing media for a specific screen or platform.
How to calculate aspect ratio +
Aspect ratio is the proportional relationship between width and height. If your image is 1920 pixels wide and 1080 pixels tall, divide both numbers by their greatest common divisor, 120. The simplified ratio is 16:9. The same ratio still applies at 1280 x 720, 3840 x 2160, or any other size that keeps the same width-to-height relationship.
How to resize without stretching +
Choose the ratio you need, then enter either the new width or the new height. The calculator updates the other dimension so the frame keeps the same shape. If the target platform requires an exact size, use that size directly. If your original image does not match the target ratio, crop when edge content can be removed, or add padding when the full image must remain visible.
Which ratio should you choose? +
Use 16:9 for most horizontal videos, YouTube thumbnails, slide decks, TVs, and modern monitors. Use 9:16 for mobile-first short video and story-style placements. Use 4:5 for portrait feed posts, 1:1 for square thumbnails and avatars, 3:2 for many DSLR photos, 4:3 for classic screens, 16:10 for some laptops and presentation displays, 21:9 for cinematic or ultrawide layouts, and 32:9 for super-wide signage or monitor content. The right choice depends on where the asset will be viewed, not only on the source file.
Why image upload detection matters +
Many users do not know the current ratio of a file. Upload detection reads the image dimensions in the browser, simplifies the ratio, and lets you resize from the real source instead of guessing. This is useful for product photos, screenshots, social media graphics, thumbnails, and design exports that came from another tool.
Ratio vs. pixels +
The ratio describes shape. Pixels describe size. A 1920 x 1080 video, a 1280 x 720 thumbnail, and a 3840 x 2160 display are all 16:9 because the width and height scale together. When you resize, choose the shape first, then choose enough pixels for the platform, screen, or print workflow.
What to measure before calculating +
Measure only the actual image, video, screen, or layout area. Do not include a video player border, browser chrome, phone bezel, frame, padding, or surrounding whitespace unless that surrounding area will be part of the exported file. Extra border pixels can make a normal 16:9 asset look like a strange custom ratio.
Use cases
Match the ratio to the job, not just the numbers.
Most aspect ratio mistakes happen because the file is resized for the wrong destination. Start with the workflow, then choose the ratio and pixel size that fit the screen, social placement, design slot, or export requirement.
Social media creators
9:16, 4:5, 1:1, 16:9
Plan vertical shorts, portrait feed posts, square crops, and horizontal thumbnails before exporting from Canva, Photoshop, CapCut, Premiere, or mobile editing apps.
- 1080 x 1920 vertical video
- 1080 x 1350 portrait feed
- 1280 x 720 thumbnail
Video editors and streamers
16:9, 21:9, 4:3, 2:1
Keep footage, overlays, webcam scenes, trailers, webinars, and cinematic crops in the correct frame so the final upload does not stretch or show unexpected bars.
- 1920 x 1080 HD export
- 2560 x 1080 ultrawide
- 1440 x 720 2:1 crop
Designers and developers
16:9, 4:3, 1:1, custom
Turn real dimensions into responsive CSS values for cards, product media, embeds, hero images, thumbnails, app screenshots, and fixed-ratio layout slots.
- aspect-ratio: 16 / 9
- square avatar crop
- responsive product card
Photographers and ecommerce
3:2, 4:3, 5:4, 1:1
Check camera photos, marketplace images, catalog crops, print previews, and product galleries before deciding whether to crop, pad, or resize.
- 1500 x 1000 DSLR photo
- 2000 x 2500 print crop
- 1200 x 1200 product image
Screens, slides, and signage
16:9, 16:10, 4:3, 32:9
Match presentations, monitor wallpapers, conference screens, LED walls, kiosk graphics, and wide banners to the display shape before the content goes live.
- 3840 x 2160 display
- 1920 x 1200 laptop screen
- 3200 x 900 ribbon display
AI image prompts
1:1, 4:5, 9:16, 16:9
Choose a target frame before generating images so the subject composition fits thumbnails, posters, vertical covers, profile images, or landscape scenes.
- square avatar prompt
- vertical poster prompt
- wide banner prompt
FAQ
Common aspect ratio questions.
What is aspect ratio? +
Aspect ratio is the width-to-height proportion of an image, video, screen, or layout. A 16:9 ratio means the frame is 16 units wide for every 9 units tall.
What aspect ratio is 1920x1080? +
1920x1080 simplifies to 16:9. It is the common Full HD widescreen format used for YouTube, TVs, monitors, and slide decks.
Can I calculate aspect ratio from an image? +
Yes. Use the image upload field on this page. The browser reads the image dimensions locally and updates the ratio without uploading the file to a server.
How do I keep the same ratio when resizing? +
Enter the ratio or choose a preset, then type either the target width or target height. The calculator fills in the matching dimension automatically.
Should I crop or add padding? +
Crop when the subject can lose edge content and you want the frame fully filled. Add padding when you need to preserve the entire original image or video.
What is the best ratio for TikTok, Reels, and Shorts? +
Use 9:16 for vertical short-form video. A common export size is 1080x1920 pixels.
What is the best ratio for Instagram feed images? +
Instagram feed images commonly use 1:1 for square posts or 4:5 for portrait posts. 4:5 gives more vertical screen space in the feed.
What does CSS aspect-ratio mean? +
The CSS aspect-ratio property tells the browser to preserve a width-to-height shape, such as aspect-ratio: 16 / 9; for a responsive video frame.
Can I use inches, centimeters, or screen panels? +
Yes, as long as width and height use the same unit. Pixels are common for web media, but the same ratio math works for inches, centimeters, feet, meters, or square display panels.
Should I include a player frame, border, or padding? +
No. Use the dimensions of the actual content area. Video controls, device bezels, browser borders, frames, and padding can change the measured shape without changing the real media ratio.
What aspect ratio should I use for YouTube thumbnails and standard video? +
Use 16:9 for standard YouTube videos and thumbnails. Common sizes include 1920x1080 for Full HD video and 1280x720 for thumbnails.
What aspect ratio should I use for AI image prompts? +
Use 1:1 for square avatars or product shots, 4:5 for portrait posts, 9:16 for vertical covers and phone-first artwork, and 16:9 for wide scenes, thumbnails, and banners.
Need another size?