オンライン動画リサイズ — 寸法と縦横比を変更
幅、高さ、縦横比をブラウザ内で変更。TikTok (9:16)、Instagram (1:1)、YouTube (16:9) のプリセットとカスタムサイズに対応。
オンライン動画リサイズ — 寸法と縦横比を変更 を3ステップで使う
- 1
Upload your video
Drop a file or browse to select. MP4, MOV, AVI, MKV, WebM supported up to 2 GB.
- 2
Pick a preset or custom size
Choose 9:16 vertical, 1:1 square, 16:9 landscape, or enter exact width × height in pixels.
- 3
Download the resized video
Processing runs in your browser via FFmpeg.wasm. Preview before exporting.
オンライン動画リサイズ — 寸法と縦横比を変更 を選ぶ理由
Preset social sizes
9:16 (TikTok/Reels/Shorts), 1:1 (Instagram feed), 16:9 (YouTube/Twitter), 4:5 (Instagram portrait).
Crop or fit
Choose cover (crops to fill) or contain (adds letterbox bars) to handle aspect-ratio changes.
Private processing
Runs entirely in your browser. Your file never leaves your device.
Custom background
Letterbox color options (black, white, blur) when adding bars for fit mode.
Free forever
Unlimited resizing, no watermark, no sign-up.
オンライン動画リサイズ — 寸法と縦横比を変更 の利用者
TikTok and Reels vertical
Turn a horizontal YouTube clip into a 9:16 vertical for short-form platforms.
Instagram square feed
Center-crop or letterbox to a 1:1 square for clean feed posts.
YouTube 16:9
Resize phone recordings to the standard 1920×1080 YouTube aspect ratio.
世界中のクリエイターのために
世界中のクリエイター、ジャーナリスト、学生、研究者のために。
よくある質問
- What output dimensions are supported?
- Presets for 9:16, 1:1, 16:9, 4:5. Custom width and height in pixels up to 4096×4096.
- Will resizing reduce quality?
- Downscaling is generally lossless at the visual level. Upscaling cannot add detail but produces a usable, larger file.
- What is the difference between cover and contain?
- Cover crops the video to fill the target size without distortion. Contain adds letterbox/pillarbox bars to preserve the full frame.
- Does the output keep the audio?
- Yes. Audio is preserved by default. An option to strip audio is available.
- Are my files uploaded?
- No. All processing runs in your browser.
- What output formats are supported?
- MP4 with H.264 is the default output. WebM is available as an alternative.