Free browser tool
Video Aspect Ratio Converter
Calculate the exact dimensions, scale, and letterbox bars to convert any video to 16:9, 9:16, 1:1, 4:5, 21:9 — or any custom ratio. Instant preview, no upload, no sign-up.
Result
16:9 (1.778)
16:9 (1.778)
1,920 × 1,080
1,920 × 1,080
None
None
Canvas: 1,920 × 1,080 (16:9)
Video sits centered. Source already matches target — no bars needed.
Aspect Ratios by Platform
Quick reference for the aspect ratio each major platform expects.
| Platform | Aspect ratio | Recommended resolution |
|---|---|---|
| YouTube | 16:9 | 1920 × 1080 |
| YouTube Shorts | 9:16 | 1080 × 1920 |
| TikTok | 9:16 | 1080 × 1920 |
| Instagram Reels | 9:16 | 1080 × 1920 |
| Instagram Post | 1:1 | 1080 × 1080 |
| Instagram Portrait | 4:5 | 1080 × 1350 |
| Twitter / X | 16:9 | 1280 × 720 |
| LinkedIn Video | 16:9 | 1920 × 1080 |
| 2:3 | 1000 × 1500 | |
| Cinematic | 2.39:1 | 2048 × 858 |
How to Convert Aspect Ratio
- 1Enter your video's original width and height in pixels.
- 2Pick a target aspect ratio — choose a preset or enter a custom W:H.
- 3Select a fit mode: letterbox to preserve the whole video, crop to fill the new canvas, or stretch.
- 4Apply the resulting dimensions inside your editor and render.
Letterbox vs. Crop vs. Stretch
Letterbox (fit) keeps the full source intact and adds black bars where the ratios don't line up. Safest choice when content matters.
Crop (fill) scales the source to fully cover the new canvas and trims the overflow. Use this when you need a pixel-perfect platform fit and the edges aren't critical.
Stretch warps the image to match. Only acceptable for minor mismatches — avoid for portraits or anything with clear straight lines.
Pair this with the screen resolution calculator and the video bitrate calculator for a complete export setup.
Aspect Ratio Converter FAQ
What is a video aspect ratio?
Aspect ratio is the proportional relationship between a video's width and height. 16:9 is widescreen (YouTube, TV), 9:16 is vertical (TikTok, Reels), 1:1 is square (Instagram), and 21:9 is ultrawide cinematic. Choosing the right ratio prevents stretching or unwanted cropping on each platform.
Does this converter change my video file?
No. This tool calculates the exact dimensions, scale, and letterbox or pillarbox bar sizes you need. Apply the resulting values inside your video editor (DaVinci Resolve, Premiere, Final Cut, CapCut) to render the converted video.
What is the difference between letterbox, crop, and stretch?
Letterbox (fit) preserves the full source by adding black bars where the ratios don't match. Crop (fill) scales the source to cover the canvas and trims the overflow. Stretch warps the source to fit exactly, distorting it. Letterbox is safest, crop is best for vertical platforms, and stretch should be avoided unless minor distortion is acceptable.
What aspect ratio should I use for TikTok, Reels, and Shorts?
Use 9:16 (1080×1920 px). All major vertical short-form platforms — TikTok, Instagram Reels, and YouTube Shorts — use a 9:16 vertical canvas.
What's the best aspect ratio for YouTube?
16:9 is the standard YouTube aspect ratio. Common resolutions are 1920×1080 (Full HD), 2560×1440 (QHD), and 3840×2160 (4K). For YouTube Shorts, use 9:16.
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