Enter your video's width and height, pick a target ratio, and get the exact crop-to-fill and fit-within pixel dimensions — plus the decimal and simplified ratio. Free, no sign-up.
ClipSpeedAI auto-reframes your landscape video into perfectly-cropped 9:16 vertical clips — face-tracked, no black bars. Paste a URL and get scored, captioned shorts ready for TikTok, Reels, and Shorts.
Reframe My Video Free| Platform | Aspect Ratio | Recommended Resolution | Orientation |
|---|---|---|---|
| TikTok | 9:16 | 1080 × 1920 | Vertical |
| Instagram Reels | 9:16 | 1080 × 1920 | Vertical |
| YouTube Shorts | 9:16 | 1080 × 1920 | Vertical |
| Instagram Feed (portrait) | 4:5 | 1080 × 1350 | Portrait |
| Instagram (square) | 1:1 | 1080 × 1080 | Square |
| YouTube (long-form) | 16:9 | 1920 × 1080 | Landscape |
| X / Twitter | 16:9 | 1280 × 720 | Landscape |
| 1:1 or 16:9 | 1080 × 1080 / 1920 × 1080 | Square / Landscape |
ClipSpeedAI auto-reframes your landscape video into perfectly-cropped 9:16 vertical clips — face-tracked, no black bars. It finds the best moments, tracks the subject, and captions everything automatically.
Get Started FreeAspect ratio is the relationship between a video's width and its height, written as width:height — for example 16:9 for a widescreen YouTube video or 9:16 for a full-screen vertical short. This tool takes your source dimensions in pixels and a target ratio, then gives you two different ways to hit that ratio: crop-to-fill and fit-within. It also shows the target ratio as a decimal (16:9 is 1.7778, 9:16 is 0.5625) and the simplified ratio computed with the greatest common divisor, so you always know exactly what shape you are working with.
These are the two honest ways to change a video's shape, and they trade off against each other. Crop-to-fill resizes the video so it completely fills the target frame with no bars, then trims whatever hangs over the edges. When you crop a 16:9 landscape into 9:16, you keep the full height and cut roughly two-thirds of the width. This is what you want for TikTok, Reels, and Shorts, because the clip fills the entire phone screen. Fit-within (letterboxing) does the opposite: it shrinks the whole frame until it fits inside the target and pads the empty space with black bars. Nothing gets lost, but you waste screen real estate, which almost always hurts short-form performance. Use fit-within only when every pixel matters — a screen recording, a slide, or an infographic where cropping would cut off information.
This is the single most common resize creators need, and it is exactly the problem ClipSpeedAI was built for. A standard 1920 × 1080 landscape frame cropped to 9:16 becomes about 608 × 1080 pixels (which scales up to the standard 1080 × 1920 short). Because you are throwing away most of the width, the danger is obvious: if your subject is not dead center, a naive center-crop will slice them out of frame. That is why professional vertical reframing tracks the subject rather than cropping to a fixed box — the crop window moves to follow the face or the action so the important part of every frame stays visible.
Getting the ratio right is only half the job; the resolution matters too. Uploading a video at a lower resolution than the platform expects makes it look soft, and mismatched dimensions can trigger the platform to add its own letterboxing. For vertical short-form, 1080 × 1920 is the safe standard across TikTok, Reels, and Shorts. Instagram's portrait feed post is 4:5 at 1080 × 1350, the square format is 1:1 at 1080 × 1080, and long-form YouTube stays 16:9 at 1920 × 1080. When you match both the ratio and the recommended resolution from the table above, your video displays cleanly with no surprise bars and no quality loss.
Most video codecs, including H.264, require both the width and height to be even numbers. This calculator rounds its results to the nearest even pixel value so the dimensions it gives you will actually encode without errors. If you plug the numbers into an editor or an ffmpeg command, they are ready to use as-is.
Use 9:16 (vertical) for TikTok, YouTube Shorts, and Instagram Reels. It fills the entire phone screen with no black bars and is the native format all three short-form feeds are built around. The standard resolution is 1080 × 1920 pixels. Anything wider (like 16:9 landscape) gets shrunk into a small letterboxed strip that kills reach, so always crop or reframe to 9:16 before posting.
You have two options. Crop-to-fill keeps the full height and trims the left and right sides so the frame becomes tall and vertical (a 1920 × 1080 landscape becomes roughly 608 × 1080, which scales up to 1080 × 1920). Fit-within keeps the whole frame and adds black bars top and bottom, which wastes screen space. For short-form, crop-to-fill almost always wins, but you have to make sure the subject stays inside the crop. ClipSpeedAI does this automatically by face-tracking the subject so the important part never gets cut off.
The standard full-HD 9:16 vertical resolution is 1080 × 1920 pixels. That is what TikTok, YouTube Shorts, and Instagram Reels expect. A 4K vertical version is 2160 × 3840, and a lighter option is 720 × 1280. As long as the width-to-height ratio stays 9:16 (a decimal ratio of 0.5625), any of these will display correctly full-screen on a phone.
Crop-to-fill resizes your video so it completely fills the target frame with no bars, at the cost of trimming the edges that do not fit. Fit-within (letterbox) shrinks the whole video to fit inside the target frame and pads the rest with black bars, so nothing is lost but screen space is wasted. For short-form vertical content, use crop-to-fill so the video fills the phone screen. Use fit-within only when you cannot afford to lose any part of the frame, such as a screen recording or an infographic where every pixel matters.
It can, if you crop blindly to the center. When you turn a wide 16:9 frame into a tall 9:16 one, roughly two-thirds of the width is removed, so a speaker standing off to one side can get clipped out. ClipSpeedAI solves this with face and subject tracking: it follows the person or the action frame by frame and keeps them centered inside the vertical crop, so the subject is never cut off and you never get black bars.