Aspect ratio calculator
Aspect Ratio Calculator
Turn any width and height into a ratio like 16:9 and get the matching size when you resize. OnVid's free aspect ratio calculator runs in your browser.
- 1Type width × height
- 2Read the ratio
- 3Resize or pick a size
- Instant results
- No sign-up
- Platform sizes built in
- Free to use
Free, no sign-up. The math runs in your browser.
- 1Type width × height
- 2Read the ratio
- 3Resize or pick a size
- Instant results
- No sign-up
- Platform sizes built in
- Free to use
Kling 3 4K · cinematic
Veo 3.1 native audio
Seedance 2 #1 arena
Wan 2.7 image-to-video
Hailuo 2.3 expressive
Hunyuan open sourceKling 3 4K · cinematicVeo 3.1 native audioSeedance 2 #1 arenaWan 2.7 image-to-videoHailuo 2.3 expressiveHunyuan open sourceWhy calculating proper dimensions matters for every display
Getting your pixel geometry right prevents awkward letterboxing, stretched faces, and unexpected interface overlaps across mobile feeds and desktop screens. Pairing accurate framing math with OnVid's AI video generator ensures your visual media fits every target display cleanly.
Frame every scene cleanly with exact ratios and sizes
Find exact dimensions right in your browser, then make the video in OnVid's AI video app after you sign up.
Use a free aspect ratio calculator
The calculator works out the exact relationship between width and height before you export your footage. Type your starting size in pixels and the reduced ratio appears, with no data sent to a server. Use it to plan 16:9, 9:16, 1:1, 4:5 or 4:3 layouts, then pick the matching shape when you make a video in OnVid's AI video app.
Resize dimensions without picture distortion
Type a new width or height and you get the matching other side, so nothing is stretched or squeezed. You never have to guess whether a scaled frame still matches widescreen 16:9. The calculator only does the math; it does not resize your file. Apply the numbers in your editor's export or canvas settings.
See the shape before you export
A preview box draws the ratio you entered, so you can see how wide or tall the frame is at a glance. Each common size also names where it is used: YouTube and TV, TikTok, Reels and Shorts, Instagram posts and portraits, classic TV and iPad, cinema and ultrawide, and Pinterest pins. It does not mark platform safe zones, so keep titles and faces toward the center of vertical frames.
Convert widescreen compositions to vertical
Turning a 16:9 landscape layout into a 9:16 vertical one means reframing, not stretching. Enter 1080×1920 and set the new height to 1080, and the width comes out at 608: that is the vertical slice of a 1920×1080 frame you can keep at full height. For short animations, OnVid's separate MP4 to GIF converter turns clips into GIFs.
Verify matching ratios before editing
Mixing media clips with mismatched frame boundaries often leads to unwanted pillarboxing bars along the side of the player. Checking each source file with a video aspect ratio calculator establishes a uniform baseline resolution across your entire timeline. This precision prevents jagged black edges when merging multiple sequences into a cohesive story. Knowing your exact numbers keeps final clips aligned across YouTube, Reels, and digital signage.
Who relies on proportional scaling for clean AI video publishing
Digital creators, editors and motion designers work out pixel dimensions before exporting assets for different screen formats.
Social AI video creators framing vertical feeds
Short-form creators work out exact 9:16 pixel sizes for TikTok, YouTube Shorts and Instagram Reels before exporting. Running the numbers early leaves room to keep captions and faces clear of the app's buttons. A 1080×1920 canvas stays the same shape on every phone, without letterboxing.
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| Model | Resolution | Max length | Best for | Speed |
|---|---|---|---|---|
| 1080p | 5s / 10s | Cinematic, multi-shot | Max quality | |
| 720p / 1080p / 4K | 8s | Native audio | Balanced | |
S2 Sora 2 | 720p / 1080p | 4s / 8s / 12s | Prompt adherence | Balanced |
| 480p / 720p / 1080p | 5s / 10s | Sharp motion | Fast | |
| 768p / 2K | 5s / 10s | 2K detail with sound | Balanced | |
| 768p | 6s / 10s | Expressive motion | Fast | |
| 1080p+ | ~20s | Unified multimodal | Max quality | |
| 480p / 720p / 1080p | 5s / 10s | References + video remix | Fast | |
| 480p / 720p | 6s | Fast clips with sound | Balanced |
Calculate aspect ratio dimensions in three quick steps
Finding clean dimensions for your next project takes a few seconds, right in your browser.
Enter your starting dimensions
Type your width and height in pixels, or tap a common size such as 16:9 (1920×1080) or 9:16 (1080×1920).
Read the ratio
See the simplified ratio, its decimal value and the platforms that use it. Near-standard sizes show ≈ 16:9 with the exact ratio next to it.
Resize, keeping the ratio
Type a new width or height and the other side is filled in. Use the numbers in your editor, or open OnVid's AI video app to make a video in that shape.
Why use an aspect ratio calculator for your next AI video?
Understanding frame proportions prevents unwanted black bars and distortion across screens. Here are the standard display formats and the simple math behind them.
How do you get 16:9 sizes for widescreen exports?
Widescreen 16:9 is the shape of YouTube videos and most desktop monitors. Start from 1920×1080 and type 1280 as the new width, and the calculator returns 720 for the height, with no manual division.
Keeping that 16:9 shape avoids black bars on standard players. Use the numbers in your editor's export settings; the calculator does the math but does not resize the file itself.
Tip: For standard high-definition widescreen displays, 1920x1080 provides a perfect sixteen-to-nine frame.
What is the math behind an aspect ratio?
Learning how to calculate aspect ratio begins with the greatest common divisor of the width and height. For a 3840 by 2160 frame, dividing both numbers by 240 reduces it to 16:9.
Scaling both sides by the same factor keeps that ratio, which is what stops stretching. The calculator does this reduction for you and also shows the decimal value, 1.778 for 16:9.
How do you calculate custom video dimensions online?
A video dimensions calculator online lets creators scale non-standard canvas sizes while keeping their proportions. Type a new width and the matching height is filled in, or type a new height to get the width.
The math runs in your browser, with no file to upload.
Info: Maintaining an exact aspect ratio avoids stretched faces and warped objects across different media players.
How does checking the ratio prevent frame distortion?
Checking the ratio first protects your footage from unwanted pillarboxing and edge cropping when you switch between delivery formats. Matching your canvas proportions before editing stops black bars from being baked into your exported video.
The calculator does not crop or resize files. For changing the files themselves, OnVid's free browser tools can convert and compress videos without uploading them to a server.
Once you know the size, the free video compressor can cap a clip at 1080p, 720p or 480p, and the video converter changes its format. Both run in your browser.
Once you know the size, the free video compressor can cap a clip at 1080p, 720p or 480p, and the video converter changes its format. Both run in your browser.
Tip: Calculate your frame proportions early to avoid awkward cropping when you make your video.
Made with OnVid
Real clips generated from a single prompt — hover any card to play.
MiniMax H3Seedance 2Kling 3Aspect ratio calculator questions, answered plainly
Straightforward answers about calculating pixel dimensions, choosing display formats and planning video projects without distortion.
What does an aspect ratio calculator do?
An aspect ratio calculator determines the proportional relationship between the width and height of an image, screen, or video frame. It takes input pixel dimensions, reduces them using the greatest common divisor, and outputs standard ratio tags like 16:9 or 9:16 to prevent visual distortion.
How does OnVid provide an aspect ratio calculator?
The aspect ratio calculator sits right on this page. It is free, needs no sign-up and runs in your browser: type a width and height to get the reduced ratio and decimal value, then scale to a new size. There is no file to upload.
What is the formula for how to calculate aspect ratio?
To calculate an aspect ratio, divide the original width and height by their greatest common divisor. For example, a 1920 by 1080 resolution shares a greatest common factor of 120, which simplifies to 16 units wide by 9 units tall.
Where can you find a 16:9 aspect ratio calculator free?
Right here on OnVid, among the free browser tools. Tap the 16:9 size (1920×1080) and type 2560 or 3840 as the new width to get 1440 or 2160 for the height.
How does a video dimensions calculator online prevent letterboxing?
A video dimensions calculator online ensures your rendered frame perfectly matches your target playback window. By scaling width and height proportionally before generating or exporting clips, you avoid unwanted black bars, pillarboxing, and stretched figures across different platforms.
What are the recommended social media video dimensions 2026?
Standard social media video dimensions 2026 center on 1080 by 1920 pixels for vertical formats such as TikTok, YouTube Shorts, and Instagram Reels. Landscape uploads for desktop web feeds and YouTube maintain 1920 by 1080, while square feeds stick to 1080 by 1080.
Can you use an image aspect ratio calculator online for photo prep?
Yes. Enter a photo's width and height to see its ratio, then type a new width to get the height that keeps the same shape, for web banners or social posts. The calculator gives you the numbers; you resize the photo in your own editor.
What features make a free aspect ratio calculator useful for editors?
Editors can compute scaled sizes, check proportions and spot near-standard sizes, such as 1366×768 shown as ≈ 16:9 with the exact ratio 683:384. It saves manual division and needs no desktop software.
How does checking the ratio help before making an AI video?
OnVid's AI video app makes videos in 9:16, 16:9, 1:1 and 4:5. Checking the ratio your platform needs tells you which one to choose, and a starting photo with the same shape is less likely to be cropped.
Why do vertical videos need safe zones beyond the aspect ratio?
Vertical video apps put buttons, captions and profile icons over the top and bottom of your video. The calculator gives the canvas size, such as 1080×1920, but does not mark safe zones, so check each platform's current guide and keep key action near the center.
Can OnVid resize or convert video files after calculating ratios?
The calculator itself does not resize files. OnVid's free browser tools can convert, compress and loop videos without watermarks, right in your browser. For brand-new footage, OnVid's AI video generator makes videos from text or photos after you sign up.
What is the difference between aspect ratio and display resolution?
Aspect ratio describes the proportional relationship between width and height, whereas resolution states the exact pixel counts. For instance, both 1920 by 1080 and 3840 by 2160 share an identical 16:9 aspect ratio despite 4K delivering four times as many pixels.
Why do some scaled video dimensions result in fractional pixels?
Scaling can land between whole pixels, for example 607.5. The calculator rounds the missing side to the nearest whole pixel. Many video encoders, including H.264 with common settings, need an even width and height, so round an odd result to the nearest even number.
Can commercial projects use videos planned with an aspect ratio calculator?
Mathematical ratio calculations carry no copyright restrictions. For media generated with OnVid, commercial use depends on the model that made the video; check the OnVid Terms of Service and the model's terms before commercial use.
What are the common mistakes when calculating aspect ratios manually?
The most common mistake is assuming a marketing label matches the exact math: 1366×768 is sold as 16:9 but is exactly 683:384. Another is forgetting that apps overlay buttons and captions on vertical videos, so key action belongs near the center.
Your first perfectly sized AI video is one prompt away
Calculate your exact dimensions right here in your browser, then turn any prompt or photo into a ready-to-share AI video.
Which vertical canvas specifications apply for social feeds?
Social media video dimensions 2026 still center on 1080×1920 for vertical video, 1080×1350 for Instagram portrait posts and 1080×1080 for square posts. Platform apps also lay captions, buttons and account names over the top and bottom of vertical videos.
The calculator gives you the canvas size, not the safe zones. Keep faces and text toward the center, and check each platform's current ad guide for its exact margins.