SNS Video Resizer

One-click resize for TikTok / YouTube Shorts / Reels / X / YouTube. Choose between crop and letterbox.

Fully local processing — your file never leaves the browser

Pick your target platform

Upload your video

🎬

Drag & drop a video, or tap to select

MP4 / MOV / AVI / MKV / WebM · No file size cap

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📐 Crop preview (green rectangle = output region · drag to reposition)

Crop position

You can also drag directly on the canvas

Letterbox / pillarbox (fit mode) Keep the whole frame and pad with black. Preserves aspect ratio.

Trim duration

optional

Start: 0:00 End: 0:00 Length: 0:00

Quality · audio · frame rate

optional

Quality

Frame rate

Audio

Watermark (overlay an image)

optional

Enable watermark

Tap to pick PNG / JPG / WebP

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Position

Size (%)

Opacity (%)

Run conversion

Popular uses

Shorts, Reels, and TikTok conversionVertical video outputResize with safe areas in mind

Next tools

Crop Video Tool Aspect Ratio Calculator Video Compressor

What this tool does

Built-in SNS aspect presets
Crop or letterbox modes
Live crop preview
Local processing

How to use

1
Pick a video
Landscape or portrait — both work.
2
Pick a target SNS
TikTok / Reels / Shorts / X / YouTube.
3
Crop or letterbox
Crop trims; letterbox keeps full frame with black bars.
4
Resize
Preview + download.

What each setting means

Crop

Trims overflow. Fine when subject is centered.

Letterbox

Adds black bars. Keeps everything visible.

Recommended settings

TikTok / Reels / Shorts

9:16, crop

Full-screen viewport.

Instagram feed

1:1, crop

Maximizes feed footprint.

YouTube landscape

16:9, letterbox if needed

Preserves original framing.

Common pitfalls

Symptom: Subject cropped out

Cause: Crop centered, subject off-center.

Fix: Use letterbox mode.

Symptom: Massive black bars

Cause: Landscape source → 9:16 letterbox.

Fix: Crop or pick a different target SNS.

Equivalent FFmpeg commands

Reference commands you can run on the desktop FFmpeg CLI.

9:16 crop (centered)

ffmpeg -i input.mp4 -vf "crop=ih*9/16:ih,scale=1080:1920" -c:a copy output.mp4

9:16 letterbox

ffmpeg -i input.mp4 -vf "scale=1080:-2,pad=1080:1920:(ow-iw)/2:(oh-ih)/2:black" -c:a copy output.mp4

Browser support & limits

MP4 output
Crop is centered only

Privacy

This tool runs ffmpeg.wasm directly in your browser. Files never leave your device — everything runs locally. Read the privacy policy →

Frequently asked questions

TikTok preferred size?

1080×1920 (9:16). This tool resizes there automatically.

Shorts vs TikTok?

Both 9:16, but Shorts ≤60s, TikTok up to 10min. Same output works for both.

Vertical → horizontal?

Use letterbox; black bars appear on the sides.

SNS Video Resizer

What this tool does

How to use

What each setting means

Recommended settings

Common pitfalls

Equivalent FFmpeg commands

Browser support & limits

Privacy

Frequently asked questions

Related tools

Related FFmpeg recipes