Choose a video
Select an MP4, MOV, or WebM and review its dimensions and aspect ratio.
Resize Video Online
Change video dimensions with standard or custom sizes and see the real output shape before processing locally.
Local video tool
Choose a video to resize
Choose a video
or drag and drop
MP4, MOV, or WebM · up to 250 MB
How it works
Set dimensions
Use a standard height or enter custom dimensions while the output-frame preview updates immediately.
Download MP4
Encoder-safe dimensions are applied and the resized MP4 is created on your device.
Resize without accidental upscaling
Standard 1080p, 720p, and 480p choices only reduce videos that are larger than the target. Custom dimensions may enlarge a video because entering them is a deliberate choice.
The preview represents the current exact-size resize behavior. With aspect lock on, proportions are preserved; with it off, the source stretches to the requested frame. Odd values are transparently rounded down for H.264 output.
Frequently asked questions
Can I keep the original aspect ratio?
Yes. Maintain aspect ratio is on by default for custom sizes and automatically calculates the paired dimension.
Will 1080p upscale a small video?
No. Standard presets never increase the source dimensions.
Why did a dimension change by one pixel?
Odd dimensions are rounded down to even values for reliable H.264/yuv420p encoding.
Is the video uploaded?
No. Resizing runs in the local FFmpeg.wasm worker.