Free tool · H.264 · Runs in your browser
Add a watermark to a video
Short answer
Choose your video and a logo image, set the position, the size as a share of the video width and the opacity, and the tool burns the logo into every frame. On a 5.1 second 1080p excerpt the default settings (18% wide, 80% opaque, bottom right) took 20 s, kept the audio sample for sample, and made a 1.60 MB file. The tool adds no mark of its own, and nothing is uploaded.
Maximum 100 MB. Both files stay on your device - the watermark is burned in locally, with no upload and no watermark of ours added.
Key takeaways
- The logo is scaled to a percentage of the video width, so it looks the same on 1080p and 4K. The default is 18% of the width, anywhere from the five positions, with a margin of 3% of the frame.
- The sound is copied, not re-encoded: the decoded audio of the output was identical to the source's on all three of our runs.
- The picture is re-encoded at the encoder default quality, so the file changed from 8.19 MB to 1.60 MB, 1.62 MB and 1.46 MB for the three settings we tested.
- SSIM against the unmarked source was 0.9757, 0.9820 and 0.9632. A bigger or more opaque logo lowers it because it changes more of the frame, not because the video is damaged.
- Time was 19 s to 20 s for the 5.1 second excerpt, roughly 4 times its length.
What the tool does to your file
The logo is made translucent, scaled against the video with scale2ref so its width is a share of the frame, and overlaid at your position. The video is then encoded again, and the audio is copied.
| Setting | Default | Range |
|---|---|---|
| Position | Bottom right | Bottom right, bottom left, top right, top left, center |
| Size | 18% of the video width | A slider in the tool |
| Opacity | 80% | A slider in the tool |
| Margin | 3% of the frame from the edge | Fixed |
| Logo file | PNG, JPEG or WebP | A PNG with a transparent background is cleanest |
| Video | H.264 (libx264), yuv420p, preset veryfast | Re-encoded once at the encoder default quality |
| Audio | Copied (-c:a copy) | Unchanged |
Measured: three settings on a 5 second excerpt
Measured on a 5 second 1920 × 1080 excerpt of Big Buck Bunny (CC BY 3.0, Blender Foundation) with a speech soundtrack. It is an animated film, not camera footage, so the sizes of camera video will differ. The tool's own ffmpeg arguments ran on the same single-thread WebAssembly engine your browser downloads; times are from a headless run and your device will differ. The logo was a solid 400 × 160 pixel rectangle made for the test, so these runs measure what the settings cost in time and size, not how a particular logo looks.
| Settings | Output size | Video bitrate | SSIM against the unmarked source | Audio | Time |
|---|---|---|---|---|---|
| default: 18% wide, 80% opaque, bottom right | 1,599,532 bytes (1.60 MB) | 2,493 kbps | 0.9757 | Identical to the source | 19.9 s |
| faint: 18% wide, 30% opaque, bottom right | 1,618,736 bytes (1.62 MB) | 2,523 kbps | 0.9820 | Identical to the source | 19.4 s |
| large centered: 40% wide, 80% opaque, center | 1,461,887 bytes (1.46 MB) | 2,278 kbps | 0.9632 | Identical to the source | 19.0 s |
The Add a watermark tool on a 5 second 1080p excerpt, 8.19 MB as published.
Choosing size, opacity and place
- Size: a starting point is 12% to 20% of the width. A mark above 30% starts to compete with the subject.
- Opacity: a starting point is 30% to 60%, visible but quiet. At 100% a logo looks stuck on.
- Place: bottom right is the conventional corner, but short-form apps put captions and buttons there. Check the safe zone before you pick a corner.
- File: use a PNG with a transparent background. A JPEG carries a solid rectangle behind the logo.
Free tools:What is a safe zone?Compress a videoCrop a video preciselySocial media image sizes
What this tool does not do
- It adds no watermark or branding of its own. The only mark on the output is the image you supply.
- It cannot remove a watermark from a video.
- It places one logo at a fixed spot for the whole clip. There is no animation.
The cost
The picture is encoded again, so the file takes a while and the quality is the encoder default, not a copy. Mark your original once. The sound passes through untouched.
Questions people ask
Does this add its own watermark?
No. The only mark on the output is the image you supply.
What image format should my logo be?
A PNG with a transparent background. JPEG and WebP work, but a JPEG has a solid rectangle behind the logo.
Does adding a watermark lower the quality?
The picture is re-encoded once: SSIM 0.9757 against the unmarked source with the default settings. The sound is copied and identical.
How long does it take?
20 s for a 5 second 1080p excerpt in a headless run of the same engine. Your device will differ.
Can I put the logo in more than one place?
No. One logo at one position. Run the tool again on the result to add a second.
Is anything uploaded?
No. The video and the logo stay on your device; each can be up to 100 MB.
Related
Sources and how we checked
- FFmpeg Filters Documentation (read 2026-10-06)
- FFmpeg wiki: Encode/H.264 (CRF and presets) (read 2026-10-06)
Reviewed October 9, 2026. The measurements ran the tool’s own ffmpeg arguments on the same single-thread WebAssembly engine your browser downloads. The script, the results and the saved documentation are in data/seo/hub/evidence/2026-10-09/tools.