Change a video's aspect ratio, free, in your browser
Drop a video and Burncaps gives it back in a new shape: Vertical 9:16, Portrait 4:5 or Square 1:1, from a landscape, square or vertical recording. You choose how the new frame is set: it follows your face, stays where you put it, or keeps the whole picture with a soft fill around it. A whole video up to ten minutes keeps every second, the shape is drawn on your device, and the video is never uploaded to us. Free for 2 videos every 30 days, with no watermark and no sign-up.
The video never leaves your browser. On a computer, the sound is heard on your own device unless you choose our speech service; on a phone, it goes to our speech service unless you keep it on the phone. The service gets short pieces of sound, never the picture.
- Video never uploaded
- Free, no sign-up
- No watermark
- 9:16, 4:5 or 1:1
Live preview, rendered on this page by the same engine that burns your video. The new shape is set on your own video, in the editor.
The four shapes, and the file each one makes
Aspect ratio is a frame's width against its height: 16:9 is wide, 9:16 is the same frame stood on its end, 1:1 is square and 4:5 is a little taller than wide. Burncaps makes three new shapes, or keeps your own.
| Shape in the editor | Ratio | The exported file | What the editor says it is for |
|---|---|---|---|
| Original | As recorded | Your video's own width and height | Keeping the frame exactly as it was filmed |
| Vertical | 9:16 | 1080 x 1920 pixels | Shorts, Reels, TikTok |
| Portrait | 4:5 | 1080 x 1350 pixels | Instagram and Facebook feeds |
| Square | 1:1 | 1080 x 1080 pixels | LinkedIn and feeds |
The last column is the editor's own label for each shape. Each app's own numbers, with the date we read them: Instagram Reel size, YouTube Shorts size and TikTok video size. Where an app's buttons and captions sit over a vertical video: the safe zone checker.
Any direction: what happens to the picture
Changing the shape either cuts a window of the new shape out of your picture (Follow me and Fixed) or fits the whole picture inside the new frame (Fit everything). These are the sizes the editor works with, for the most common recordings.
| From | To | Follow me or Fixed cuts a window of | Enlarged? | Fit everything places the whole picture at |
|---|---|---|---|---|
| Landscape 16:9, 1920 x 1080 | Vertical 9:16 | 608 x 1080 | About 1.8 times, so a little softer, and the editor says so | 1080 x 608, the fill above and below |
| Landscape 16:9, 1920 x 1080 | Portrait 4:5 | 864 x 1080 | 1.25 times | 1080 x 608, the fill above and below |
| Landscape 16:9, 1920 x 1080 | Square 1:1 | 1080 x 1080 | No | 1080 x 608, the fill above and below |
| Vertical 9:16, 1080 x 1920 | Square 1:1 | 1080 x 1080 | No | 608 x 1080, the fill left and right |
| Vertical 9:16, 1080 x 1920 | Portrait 4:5 | 1080 x 1350 | No | 759 x 1350, the fill left and right |
| Square 1:1, 1080 x 1080 | Vertical 9:16 | 608 x 1080 | About 1.8 times | 1080 x 1080, the fill above and below |
| Landscape 4K, 3840 x 2160 | Vertical 9:16 | 1215 x 2160 | No: it is made smaller to 1080 x 1920, so it stays sharp | 1080 x 608, the fill above and below |
| Vertical 9:16, 1080 x 1920 | Vertical 9:16 | Nothing changes. The editor says "Your video is already 9:16, so it keeps its own frame." | ||
Worked out with the editor's own framing code (js/frame.js) on 3 November 2026. A shape within 2% of your video's own counts as your video's shape and is kept as recorded. When the window is enlarged more than one and a half times, the editor's summary line says "zoomed in to fill the shape, so a little softer than the original". Fixed can also zoom in, up to twice, which enlarges the window further.
Three ways to set the new frame
Follow me
The editor looks for your face through the whole video, every half second (every second once a video passes three minutes), and plans a camera path: still while your face stays near the middle of the frame, a smooth, speed-limited move when you step away. The path is planned forwards and backwards through the video and the two are averaged, so the frame starts to move just before you do. If no face is found, the frame stays in the centre.
Fixed
You place the frame. Drag the picture, or select it and use the arrow keys, and zoom from 100% to 200%. Recentre puts it back on your face, or in the middle. The frame then holds that place for the whole video, which suits a speaker who does not move or a shot that should not move.
Fit everything
Nothing is cut: the whole picture sits inside the new frame, as large as it fits. The space around it is filled with the same picture, very soft and a little darker. If you chose a background under Background (a colour, a studio backdrop or your own picture), that fills the space instead, and with the green screen it is green.
Every caption style and background works in every shape. On a vertical frame the captions move to where the apps leave room for them, unless you have already placed them yourself.
How to change a video's aspect ratio
Six steps, with no account, on a phone or a computer. The new shape runs from the first second to the last.
- Drop the video. An MP4 or MOV up to ten minutes and 1.2 GB, landscape, square or vertical. It opens in this page and is never uploaded to us.
- Let it listen. Burncaps writes down every word, for captions you can keep or leave out.
- Open the More tab, then Shape. Choose Original, Vertical 9:16, Square 1:1 or Portrait 4:5. The preview changes at once.
- Choose the framing. Follow me, Fixed or Fit everything appears under Framing as soon as the new shape differs from your video's own.
- Keep the captions, or not. Pick one of 60 caption styles in the Style tab, or choose No captions to change only the shape.
- Export. You get a new MP4 in the new shape, its name ending -vertical, -4x5 or -square. The sound is left as recorded.
The editor remembers the shape and framing you chose on this device, so the next video opens with them. Only turning a landscape video vertical has its own page: horizontal to vertical video.
Clips from a longer recording take the same shapes
For a podcast, call or talk over ten minutes, up to three hours, choose Clips. Burncaps finds the moments worth posting and cuts each into a captioned clip of up to 3 minutes, Vertical 9:16 by default. In the More tab, Frame changes it to Portrait 4:5, Square 1:1 or Keep original, and Layout chooses Fill (the frame follows whoever is talking), Fit (the whole picture, its colours blurred behind) or Split (two people, one above the other).
A clip is an edit, not a straight copy: ums and stutters are cut, long pauses are shortened and the sound is levelled. For every second as recorded, use the whole video. Long video to Shorts explains how the clips are chosen.
What it does not do
It makes three shapes and no others: no 16:9, 4:3, 21:9 or 2:3 output, so a vertical or square video cannot be turned into a wide one (Original keeps it as it is). It does not let you pick a resolution, bitrate or file size: a new shape is always 1080 pixels wide. It does not rotate a video that plays on its side because the phone was turned. It works on one video at a time, with no batch and no API. A whole video changes shape up to ten minutes; a longer recording changes shape only as clips of at most 3 minutes. And Follow me looks for faces, so it is made for people talking, not for a ball or a car.
Where your video goes
The video stays in your browser, and the new shape is drawn on your device. On a computer, English is heard on your own device unless you choose our speech service; on a phone the sound goes to our speech service unless you keep it on the phone. The service gets short pieces of sound, never the picture. The script's text leaves your device only if you type names to spell right, choose a translation or choose Clips (it then goes to our AI); ticking Keep everything on this device stops that. Every request the page can make.
What it costs
Free: 2 videos every 30 days, each with captions and up to 3 clips, no watermark, no sign-up. Then try Captions + Clips free for 7 days, no card. Captions + Clips is $29 a month for unlimited clips and captions; Captions is $9.98 a month or $49 once.
Questions, answered plainly
How do I change the aspect ratio of a video for free?
Drop the video, an MP4 or MOV up to ten minutes, on this page. When the editor opens, go to the More tab, then Shape, and choose Vertical 9:16, Portrait 4:5 or Square 1:1; then choose Follow me, Fixed or Fit everything, and export a new MP4. Nothing is cut from the length. Free is 2 videos every 30 days, each with captions and up to 3 clips, no watermark, no sign-up.
Can I change a vertical video to square or 4:5?
Yes. Choose Square 1:1 or Portrait 4:5 for a vertical video. Follow me and Fixed cut a square or 4:5 window from the tall picture, which needs no enlarging from a 1080 x 1920 video; Fit everything keeps the whole tall picture in the middle with a soft fill on either side.
Can I change a video to 16:9?
No. The new shapes are Vertical 9:16, Portrait 4:5 and Square 1:1. A landscape 16:9 video can keep its own shape (Original), but a vertical or square video cannot be turned into a wide one.
Will changing the aspect ratio cut off part of the picture?
With Follow me or Fixed, yes: a window of the new shape is cut from your picture, and the rest is left out. With Fit everything, no: the whole picture sits inside the new frame and the space around it is filled with a soft, darker copy of the same picture, or with the background you chose.
Does changing the aspect ratio lower the quality?
Only when the window has to be enlarged. A 1080p landscape video cut to vertical 9:16 is enlarged about 1.8 times, so it is a little softer, and the editor says so; cut to square it is not enlarged at all. A 4K recording cut to vertical is made smaller, so it stays sharp. Fit everything never enlarges a 1080p or 4K picture.
How long can the video be?
A whole video changes shape up to ten minutes and 1.2 GB. A longer recording, up to three hours, changes shape only as clips: each clip is at most 3 minutes, and in a clip ums and stutters are cut and long pauses shortened.
Is my video uploaded?
No. Burncaps opens the video in your browser and never receives it. On a computer, the sound is heard on your own device unless you choose our speech service; on a phone it goes to our speech service unless you keep it on the phone (short pieces of sound, never the picture, to Microsoft's speech recognition in the EU, which by Microsoft's terms for the service stores none of it).
Burncaps facts, checked 3 November 2026
What it is: a browser tool that burns animated word-by-word captions into a talking video, or finds the best moments of a talk, podcast or interview and gives them back as ranked, captioned 9:16 clips.
Price: free for 2 videos every 30 days, each one recording with its captioned video and up to 3 clips, no mark and no sign-up; then the free 7-day Captions + Clips trial, no card (your email only); then Captions + Clips, $29 a month, gives unlimited clips and captioned videos, or Captions, $9.98 a month or $49 once, gives unlimited captioned videos. Captions paid once is not a subscription.
Privacy: the video never leaves your browser. The sound goes only to our speech service, on a phone unless you switch it off, on a computer only if you choose it. Because the video never reaches us, we cannot keep it or train AI on it, and we train no AI on anything you make.
Files: MP4 or MOV in, MP4 out. Captions on the whole video: up to ten minutes. Clips: up to three hours, on a phone or a computer. SRT, VTT, ASS and text files are free without limit for recordings up to ten minutes; a longer recording, up to three hours, gives its script and those files (the first ten minutes free, all of it as one of your free videos, in the trial or with Captions + Clips or Captions) and its clips (every one found and shown before you sign up; up to 3 from each free video exported free, every one in the trial or with Captions + Clips).
Clips: about one clip for every two minutes of talk, up to 30, ranked, the ones we would post first circled, each showing the words it opens and ends on and the reason it was chosen; each cut to 9:16 with ums and dead air removed, an opening card and captions, framed on whoever is talking. Every clip of the whole recording is found and shown, free and with no sign-up; each free video exports up to 3 of them, and the 7-day trial and Captions + Clips export every clip, unlimited.
Languages and styles: captions in the language spoken, twelve Indian languages heard on your device, translation into 59 languages, 60 caption styles.
After it listens: correct any word (one click changes it everywhere), add or cut words, one to six words at a time, position, size, text and highlight colours, and names this browser remembers, all free and without listening again.
Made by: Jordan Labs Ltd, UK company no. 17358646.
Against other tools: sixteen caption tools compared, from the vendors' own pages.