Compress any video to any exact size
Stop guessing with Low / Medium / High. Tell VidSizer the exact size you need — 20 MB for Discord, 16 MB for WhatsApp, or any custom number — and get a video back just under the limit.
Drop your video here
or
MP4, MOV, WebM… — processed 100% on your device
Target size
Loading encoder…
🔒 Your video never leaves your device. No upload, no signup, no watermark.
How it works
Drop your video
Your file is read locally in the browser. Nothing is uploaded to any server.
Pick an exact size
Choose a platform preset (Discord 20 MB, WhatsApp 16 MB…) or type any custom MB number.
Download the result
VidSizer computes the precise bitrate, encodes (up to 3 verify-and-retry passes), and hands you a file just under your limit.
Why exact size beats "Low / Medium / High"
Most compressors ask you to pick a quality preset and hope the output fits. That is backwards: the platform doesn't care about your quality setting — it cares about megabytes. A 3-minute 4K clip on "Medium" can still be 80 MB, and Discord will still reject it.
VidSizer starts from the number that actually matters. It reads your video's duration, solves for the exact bitrate that fits your target (minus a 4% safety margin and audio), then verifies the output and re-encodes if it overshoots. If your clip is simply too long for the target, it tells you honestly before you waste time — instead of silently handing you a 400p mess.
Popular targets
FAQ
Is VidSizer really free?
Yes. Because compression happens on your own device, there is no server bill to cover — so there is nothing to charge for. No account, no watermark, no capped "free tier".
Does my video get uploaded to your servers?
No. There are no servers involved at all. The video encoder (FFmpeg) is downloaded once into your browser and runs locally. Your file never leaves your device.
How can the output be an "exact" size?
File size ≈ bitrate × duration. VidSizer measures your video's duration, subtracts the audio track's share and a 4% safety margin, and solves for the video bitrate that lands just under your target. After encoding it checks the real file size and re-encodes up to 3 times if it overshoots.
What formats can I upload? What do I get back?
MP4, MOV, WebM, MKV and most common formats work as input. Output is always MP4 (H.264 video + AAC audio) with faststart enabled, so it plays everywhere and uploads cleanly.
Will quality suffer?
It depends on the math: a 30-second clip at 20 MB looks great; a 20-minute clip at 20 MB cannot. VidSizer warns you honestly when the target is unrealistic for the clip length, and suggests a bigger target or trimming.
Why is my video scaled to 720p?
For small targets (like 20 MB), keeping 1080p or 4K resolution forces an extremely low bitrate per pixel, which looks worse than a clean 720p encode. Videos taller than 720p are scaled down; smaller videos keep their native resolution.