Video Resizer
Reshape a video to 9:16, 1:1, 4:5 or 16:9: crop and position it, or fit it over blurred bars.
- Free
- No sign-up
- No watermark
- Runs in your browser
Loading the tool.
Video sizes for each platform
Every app has one shape it shows full screen or full width. Upload a different one and the app decides for you: it trims the sides or shrinks the video between bars. Below are the shapes and pixel sizes this resizer exports, one preset each. Apps adjust their layouts from time to time, so read them as this tool's presets, not a platform rulebook.
| Platform | Aspect ratio | Resolution (pixels) | Where it shows |
|---|---|---|---|
| TikTok | 9:16 | 1080 × 1920 | Full screen in the For You feed |
| Instagram Reels | 9:16 | 1080 × 1920 | Full screen in the Reels feed |
| YouTube Shorts | 9:16 | 1080 × 1920 | Full screen in the Shorts feed |
| Portrait feed post | 4:5 | 1080 × 1350 | Portrait posts in Instagram and Facebook feeds |
| Square posts | 1:1 | 1080 × 1080 | Feed posts on Instagram, Facebook and LinkedIn |
| YouTube and landscape video | 16:9 | 1920 × 1080 | Regular YouTube videos, websites, TVs and laptops |
Each size is its aspect ratio at 1080 pixels on the short side: 1080 ÷ 9 × 16 = 1920 and 1080 ÷ 4 × 5 = 1350. A crop of a 16:9 frame keeps all of its height and a share of its width equal to the target ratio divided by 16/9: 81/256 (about 32%) for 9:16, 45% for 4:5 and 56% for 1:1. For 9:16 the kept width in pixels is the height × 9/16, rounded down to an even number because video encoders need even sizes: 606 × 1080 from a 1080p source, 1214 × 2160 from 4K.
How it works
Open the video. Drop the file on the box or pick it from your device. The tool reads its size, length and codecs, then shows a frame from the first second so you can see what you are framing.
Pick a shape and frame it. Choose 9:16, 1:1, 4:5 or 16:9. With Crop to fill, drag the outlined box over the frame or use the position slider until the subject sits where you want it. With Fit inside, the whole picture stays and you choose black, white or blurred bars.
Export the MP4. Press Resize and follow the progress bar, then play the result right on the page before you download it. The file is an H.264 MP4 with the original sound, named after your video and its new shape.
What you get
- You decide what stays in the shot
- The outlined box shows exactly which slice of the frame survives the crop, and the dimmed area shows what goes. Drag it with a mouse or a finger, or move it from edge to edge with the arrow keys on the slider.
- Bars that match the video
- Fit inside can fill the empty space with a softened, darkened copy of the same frame instead of flat black, so a landscape clip in a vertical feed looks intentional rather than letterboxed.
- Upscaling is never hidden
- When the part you keep has fewer pixels than the preset, the tool says so, names the source resolution, and lets you export at the size you actually have instead of enlarging it.
- Phone clips stay upright
- Phones often store a video's rotation as a flag in the file rather than in the pixels. The resizer applies that flag before it crops, so the box you drag is the box you get.
Questions people ask
How do I convert a 16:9 video to 9:16?
Choose Vertical 9:16, keep Crop to fill, drag the box over the part of the frame you want to keep and press Resize. The tool cuts a vertical slice out of the landscape frame and scales it to 1080 × 1920. If nothing may be cut, choose Fit inside and the full frame sits between bars instead.
How much of the picture is cut when I crop landscape to vertical?
About two thirds of the width. A 9:16 slice of a 16:9 frame keeps 81/256 of the width, roughly 32%, and all of the height. A 4:5 crop keeps 45% of the width and a square keeps 56%. Fit inside cuts nothing, at the cost of bars above and below the picture.
Will resizing make my video blurry?
Only when the part you keep is smaller than the export size. A 4K source cropped to 9:16 still has 1214 × 2160 pixels, more than 1080 × 1920 needs. A 1080p source leaves 606 × 1080, which has to be enlarged; the tool marks that as upscaled and offers the smaller size without enlargement. The video is re-encoded once either way.
Can I resize a video for TikTok on my phone?
Yes, in a mobile browser with WebCodecs: Chrome on Android, or Safari 16.4 or newer on an iPhone (26 or newer for full audio support). The crop box follows your finger. A long 4K recording can run out of a phone's memory, so trim it to the part you need first.
How long does resizing a video take?
Roughly in proportion to its length, because every frame is decoded, redrawn and encoded again on your device. In our tests in desktop Chrome, a 12-second 720p clip took between 5.5 and 7 seconds to crop to 9:16 at 1080 × 1920. Keep the tab in front while it runs: browsers slow down work in background tabs.
What file do I get, and how big is it?
An MP4 with H.264 video and AAC audio, the most widely supported combination, at the size shown under the settings. Its weight depends on length and detail: the same 12-second clip came out at 1.6 to 2.3 MB at 1080 × 1920, depending on which part of the frame was kept. To make it smaller, run it through the video compressor afterwards.
Does the resizer upload my video to crop it?
No. Reading the file, drawing each frame into the new shape and encoding the MP4 all happen inside this browser tab, using the video engine built into the browser. There is no upload step, so there is nothing waiting in a queue and nothing to delete afterwards.
Want the frame to follow the speaker?
This tool holds one crop position for the whole video, so anyone who walks across the frame can walk out of it. GPT-Video's auto reframe tracks the speaker's face through the clip and moves the vertical window with it, and the AI clip generator picks the clips out of the long video in the same pass.
Related
Your file is processed on your device and never uploaded.