Pick the platform, not the maths: Reels, Shorts, Stories, feed posts and pins are all here by name, with the crop shown before you export.
Private, nothing leaves your device No sign-up100% free
Drag & drop a video (MP4, MOV, WebM, MKV), or click to browse
Choose fileChoose Instagram Reels, YouTube Shorts, Facebook feed, LinkedIn or a Pinterest pin and the tool fills in the pixels for you, then shows the exact crop box before you export. Runs in your browser, free, with no sign-up and nothing uploaded.
The discarded strip is shown before you spend an export
Nine shapes, named after the thirty places people post them
The resize runs on your device, the file is never uploaded
Every row here is a button in the tool above: pick the platform, pick the placement, and the pixels are filled in for you. Sizes repeat across platforms on purpose, because one export often covers several of them.
Choose an MP4, MOV, WebM or MKV. It stays on your computer and is never sent anywhere.
Tap the app tile: Instagram, TikTok, YouTube, Facebook, X, LinkedIn, Pinterest, Snapchat or WhatsApp, then the placement. The pixel size fills itself in, and the badges underneath show every other platform that same size fits.
The bright frame is your output. Drag the picture under it with a finger or the mouse, pinch or scroll to zoom, and everything dimmed outside the frame is what the crop throws away. Switch to fit with bars if the crop takes too much.
The video is re-encoded in your browser at the new size, then you download a clean MP4.
The preview rectangle is calculated from the same width, height and fit values the encoder receives, so what you see dimmed is precisely what the export discards. No tool that makes you encode first can tell you this.
Crop to fill keeps a window of your clip and scales that window up to the output, so a 1080p clip going to Reels is enlarged 1.8 times even though 1080 is the smaller number. Every size shows that factor as you zoom, and 1440p and 4K switch themselves off the moment they would be enlarged at all.
Each fit mode is a thumbnail of your own clip at the size you picked: crop to fill dims what it will cut, fit with bars shows the bars it adds, and stretch shows the picture squeezed to fit. Every size on the list is drawn the same way. Pick by looking, not by guessing what the word means.
You do not have to know that Instagram portrait is 4:5. Pick Instagram, pick Feed portrait, and it exports 1080x1350. Reels and Stories, TikTok video, YouTube Shorts and 1080p, Facebook feed, X posts, LinkedIn feed, Pinterest pins, Snapchat Spotlight and WhatsApp Status are all listed by name.
Most of these placements share pixels: 1080x1920 is Reels, Stories, TikTok, Shorts, Spotlight and WhatsApp Status all at once. The tool says so under the size you picked, so you export once instead of five times.
Choose an output larger than your source and it says the file will be upscaled, not sharpened. Choose 1440p or 4K and it says a browser encoder may not manage it. Both are said before you press the button, not after.
Decoding, scaling and re-encoding all happen through WebCodecs in your browser. Your footage never leaves the machine, and no account is required.
The output is a plain MP4 with nothing stamped on it, at the exact pixel size you picked.
Most footage is shot 16:9 landscape and every short form platform wants 9:16 vertical. Those two shapes are very far apart: filling a vertical frame from a landscape source keeps only about a third of the picture width, which is why so many reposted clips have heads cropped in half. The useful question is not how to resize, it is what the resize will cut.
That is the question this page answers before you commit. Load the clip, pick 1080x1920, and the preview dims the strips that will be discarded and outlines what survives. If the subject sits off centre and the crop would clip them, you can see it immediately and switch to fit with bars instead of finding out after an export.
Crop to fill scales the video until it covers the new frame and cuts whatever hangs over. It gives a full bleed result with no bars, at the cost of everything outside the box. This is what you want for a talking head that sits near the middle of frame.
Fit with bars scales the video until it fits inside the new frame and pads the rest, which keeps every pixel of the original. It is the honest choice for wide shots, sports and anything where the edges carry information. Stretch keeps everything without bars by distorting the picture, and is only reasonable when the two shapes are already close.
Changing the aspect ratio always means re encoding, because the pixel grid itself changes. This tool decodes your video and re-encodes it to H.264 at the size you chose, using the browser hardware pipeline, so a short clip finishes quickly and the result plays everywhere.
One practical note on quality: cropping into a 1080p landscape clip to make a 1080x1920 vertical means scaling a roughly 600 pixel wide region up to 1080 wide. That is normal for short form video and looks fine on a phone, but it is not magic. If you have the option, shooting or exporting the source at a higher resolution gives the crop more to work with.
Drop the video in, pick the 9:16 vertical preset, and choose crop to fill or fit with bars. The preview shows the crop box before you export, then you resize and download the MP4.
Going from 16:9 to 9:16 with crop to fill keeps roughly 32 percent of the frame area, so about 68 percent is discarded. The tool dims the part that is going away, and you choose which part by dragging the picture under the frame and zooming.
Yes. Choose fit with bars. The video is scaled to fit inside the new frame and the remaining space is padded, so every pixel of the original survives.
No. Decoding, scaling and encoding all happen in your browser through WebCodecs, and the MP4 is built on your own device. No account, no upload.
Reels and Stories are 1080x1920 (9:16). A feed post is 1080x1350 for portrait, which is the tallest the feed allows, 1080x1080 for square, or 1080x566 for landscape. Pick Instagram in the tool and each one is a single tap.
Reels and Stories are 1080x1920 (9:16). In the feed, use 1080x1350 for vertical, 1080x1080 for square, or 1920x1080 for landscape. The same 1080x1920 file also works on Instagram, TikTok, Shorts, Snapchat and WhatsApp Status.
Shorts are 1080x1920 (9:16). Regular videos are 16:9: 1920x1080 for 1080p, 1280x720 for 720p, and 2560x1440 or 3840x2160 if your source is genuinely that sharp. Resizing a 1080p clip up to 4K would add pixels, not detail, so the tool switches 4K and 1440p off for a clip that cannot fill them.
Nine: 1080x1920 (9:16), 1080x1350 (4:5), 1080x1080 (1:1), 1080x566 (1.91:1), 1000x1500 (2:3 Pinterest pin), 1920x1080 and 1280x720 (16:9), plus 2560x1440 and 3840x2160. Between them they cover Instagram, TikTok, YouTube, Facebook, X, LinkedIn, Pinterest, Snapchat and WhatsApp.
Changing the aspect ratio requires re-encoding, so there is some loss. Cropping in also scales a smaller region up to the output width. For short form video on a phone this is normal and looks fine, and a higher resolution source gives a better result.
No. You get a plain MP4 at the exact size you selected, with nothing added to it.
The preview uses your browser to play the source. If the browser cannot decode that codec, for example some HEVC or ProRes recordings, the preview is unavailable and the tool says so. Resizing may still work, and converting to MP4 first usually fixes it.
Load a video, pick the platform by name, see exactly what the crop takes, and export the shape that platform wants. Free, private, no account.
Runs entirely in your browser. Your files never leave your device.
