動画クロッパー 9:16
Convert horizontal video to vertical 9:16, square 1:1 or portrait 4:5 for TikTok, Reels and Shorts. Trim, crop and export — all in your browser. No upload, no signup, no watermark.
動画をここにドロップまたはクリックして選択
MP4、MOV、WebM — ブラウザがデコードできる任意の形式
最良のパフォーマンスのため、クリップを2分以内に保ってください
ハンドルをドラッグしてトリミング。プレビュー内をドラッグしてクロップ矩形を再配置。
Convert horizontal video to vertical — for free, in your browser
Tools like OpusClip and Munch charge $20-50 / month to take a horizontal video and reframe it to 9:16 for TikTok, Reels and YouTube Shorts. They process on their servers and limit the number of clips you can make per month. This page does the same job 100% in your browser, with no subscription, no upload, no watermark and no monthly cap.
仕組み
We use WebCodecs, the modern browser API that exposes hardware-accelerated video encoding directly to JavaScript. When you click Export:
- The original video is decoded by your browser (whatever codec it supports).
- Each frame is drawn to an offscreen canvas at the target aspect ratio, with the chosen crop region.
- The frames are re-encoded with VideoEncoder — to H.264 for MP4 output or VP9 for WebM.
- Audio is decoded with Web Audio API and re-encoded with AudioEncoder (AAC for MP4, Opus for WebM).
- Everything is packaged into a downloadable file using a small WASM-free muxer library.
各プラットフォームのアスペクト比
- 9:16 — TikTok, Instagram Reels, YouTube Shorts, Facebook Stories, Snapchat.
- 1:1 — Instagram feed (square posts), Twitter/X.
- 4:5 — Instagram feed (portrait posts) — takes more vertical screen space than 1:1.
- 16:9 — YouTube long-form, X video posts. Useful for re-formatting a vertical clip back to horizontal.
トリミングと再配置
After loading a video, drag the two indigo handles on the timeline to set the start and end of your clip. Drag inside the video preview to reposition the crop rectangle — handy if the action isn't in the center of the frame. Choose "Left", "Right", "Top" or "Bottom" alignment as a starting point.
MP4 vs WebM — どちらを選ぶ？
MP4 (H.264) works literally everywhere — every social platform, every device, every editing tool. WebM (VP9) produces smaller files at the same quality but TikTok, Instagram and most editing tools will reject or transcode it. Use MP4 unless you specifically need WebM.
プライバシー
Your video never leaves your device. All decoding, cropping and encoding happens in your browser tab using your CPU and GPU. We don't have a server-side component for this tool. The browser tab can be closed at any time and nothing remains.
Browser support
WebCodecs is supported in Chrome 94+, Edge 94+ and Safari 16.4+. Firefox: WebCodecs support has been catching up — check version 130+. We feature-detect and show a clear notice if your browser can't handle it.
Limits
- Length: under 2 minutes works best — longer clips take time and memory.
- Resolution: anything up to 4K decodes fine; output is capped at 1080p to keep encoding fast.
- Codecs: input must be playable by your browser (MP4, MOV, WebM standard codecs all work).
Common use cases
- Repurpose a horizontal YouTube clip as a TikTok / Reel without paying OpusClip.
- Crop a podcast clip vertically for Instagram Stories.
- Trim a long screen recording down to just the interesting 30 seconds.
- Convert a square Instagram post to portrait 4:5 for better feed visibility.
- Resize a webinar recording from 16:9 to 1:1 for X (Twitter) posts.
よくある質問
- 動画をどのアスペクト比にクロップできますか？
- 9:16（TikTok/Shorts/Reels）、16:9、4:3、1:1、およびカスタム比率に対応しています。
- 動画をサーバーにアップロードしますか？
- いいえ、すべての処理はWeb APIを使用してブラウザ内で行われます。
- どの動画形式に対応していますか？
- MP4、WebM、およびブラウザがサポートするほとんどの形式に対応しています。
- ファイルサイズ制限はありますか？
- 厳密な制限はありませんが、大きなファイルほどブラウザメモリが必要です。500MB未満で最適に動作します。
- このビデオクロッパーは無料ですか？
- はい、ウォーターマークなし、サインアップ不要で完全に無料です。