Upscale Video to 4K Free: No Upload, No Watermark
Turn 720p, 1080p or 1440p video into 3840x2160 right in your browser. Drop a file, keep the 4K target and download the result. Nothing is uploaded, nothing is stored. No sign-up, no watermark, up to 10 videos at once.
- True 3840x2160 output
- GPU accelerated
- Batch up to 10 files
- No watermark
⚠️ Performance Warning
- If you don't have a graphics card (GPU), rendering will be slow. A GPU finishes short clips in seconds, a CPU can take several minutes.
- Please upload large files (close to 300 MB) one by one or in very small batches.
- Do not upscale 4K resolution for all 10 files at once. Please try batches of 2 to 5 files for 4K.
- Processing speed depends heavily on your GPU, CPU, and system memory.
- Mobile devices will be significantly slower than laptops and desktop PCs.
- 100% Secure
- No Upload
- No Storage
- No Sign-up
- Runs in Browser
- No Watermark
How do I upscale a video to 4K for free?
Drop your video into the tool above, keep the 4K target, click Start Upscale and download the 3840x2160 MP4. It runs on your own device with your GPU when available, so nothing is uploaded and no watermark is added. It sharpens what is already in your video and cannot recover detail that was never recorded, so clean 720p and 1080p sources give the best results.
- Price
- Free
- Account required
- No
- Video uploaded to a server
- No, processed in your browser
- Watermark
- None
- 4K output size
- 3840x2160 for 16:9 video, short side 2160 px
- Input formats
- MP4, WebM, MOV, MKV, 3GP (browser dependent)
- Output formats
- MP4 (H.264) and WebM
- File limit
- Up to 300 MB and 3 minutes per file, 10 files per batch
- Speed
- Seconds to a few minutes on a GPU, longer on the CPU engine
What each resolution becomes at 4K
4K means 3840x2160, so the short side of the frame is set to 2160 px and your aspect ratio is kept. The bigger the jump, the more the result depends on how clean the source is.
| Your video | Scale to 4K | What to expect |
|---|---|---|
| 360p (640x360) | 6x | Much larger, but still soft. Use Resolution mode, because Factor mode stops at 4x. |
| 480p (854x480) | 4.5x | Cleaner edges, limited real detail. Use Resolution mode. |
| 720p (1280x720) | 3x | Good on clean footage, animation and screen recordings. |
| 1080p (1920x1080) | 2x | The best case. A clean 2x step gives the most natural result. |
| 1440p (2560x1440) | 1.5x | A small gain, useful mainly when you must deliver 4K. |
Want a different size? The main Video Upscaler also offers 2x, 3x, 4x and 720p, 1080p or 2K targets.
How to upscale a video to 4K in 3 steps
- 1
Drop your video
Choose up to 10 files, or drag them onto the tool. They open in your browser and are never uploaded.
- 2
Keep the 4K target
The 4K (3840x2160) target is already selected. Pick Fast, Balanced or Best quality if you are on the CPU engine.
- 3
Upscale and download
Click Start Upscale, wait for the progress bar, then download the 4K MP4. Several files come as one ZIP.
Which quality setting should I pick?
The presets apply to the CPU engines. When your GPU is used, the AI pass runs at its own fixed quality, so you can leave the setting alone.
Fast
Quickest. Softer edges. Best on CPU-only devices and for long clips.
Balanced
Bicubic scaling. A good middle ground between time and sharpness.
Best
Lanczos scaling, the sharpest and the slowest. Use it for short, important clips.
What 4K upscaling can and cannot do
An honest look so you know what to expect. Trim long clips first with the Video Trimmer, and shrink the big 4K file afterwards with the Video Compressor.
What works well
- Turn 720p, 1080p or 1440p footage into a true 3840x2160 file
- Sharpen soft edges and lines compared with plain resizing
- Handle vertical video: the short side is set to 2160 px, so 1080x1920 becomes 2160x3840
- Keep your audio on MP4 output and upscale up to 10 videos in one batch
What to keep in mind
- Add detail that was never recorded, so a blurry 480p clip becomes a large blurry 4K clip
- Go beyond 4K, or shrink a video that is already 4K or larger
- Process files over 300 MB or 3 minutes, or live streams
- Run fast without WebGPU: devices without it use the CPU and can take several minutes
ToolDeck vs desktop and cloud 4K upscalers
A general comparison by type of tool. Desktop apps and some cloud models can add generated detail and go beyond 4K, but they need an install or an upload. Exact features vary by product.
| Feature | TToolDeck | Desktop AI upscalers | Typical cloud upscalers |
|---|---|---|---|
| Video stays on your device | Yes | Yes | No |
| Runs in the browser, no install | Yes | No | Yes |
| Free to use | Yes | Partial | Partial |
| No sign-up needed | Yes | Partial | Partial |
| No watermark on output | Yes | Yes | Partial |
| Maximum output | 4K (3840x2160) | Often 4K to 8K | Often capped on free plans |
| Invents new detail | No | Some models do | Many models do |
| Longest clip | 3 minutes | Limited by your hardware | Often limited on free plans |
Upscale video to 4K: questions people ask
Quick answers about quality, source resolutions, speed, file size and limits.
How do I upscale a video to 4K for free?
Open the tool above, drop your video, keep the 4K target and click Start Upscale. The video is processed in your browser, so there is no upload, no sign-up and no watermark. When it finishes, download the 4K MP4.
Is this really 4K, or just a bigger file?
The output is a genuine 3840x2160 video, which is the 4K UHD standard. What it cannot do is create detail that was not in the original. Edges and lines are sharpened, so the picture looks cleaner, but a soft source stays soft at a higher pixel count.
Can I upscale 1080p to 4K?
Yes, and it is the best case. 1920x1080 doubles exactly to 3840x2160, so each source pixel maps to a clean 2x2 block before sharpening. Most people see the most natural result from 1080p sources.
Can I upscale 720p to 4K?
Yes. 720p to 4K is a 3x step (1280x720 becomes 3840x2160). It works well on clean footage, animation and screen recordings. Noisy or heavily compressed 720p will look larger rather than truly sharper.
Can I upscale 480p or 360p to 4K?
The tool allows it, but be realistic. 480p needs about 4.5x and 360p about 6x. Use Resolution mode and choose 4K, because Factor mode only goes up to 4x. The result is cleaner edges at a much larger size, not a sharp HD picture.
Will 4K upscaling make my video look better?
It helps most on clean sources, anime, cartoons, game captures and screen recordings, where sharper edges are easy to see. It helps least on noisy phone footage, where there is little real detail to sharpen. Check one short clip first.
Is my video uploaded anywhere?
No. The video is decoded, upscaled and re-encoded in your browser. Open your browser Network tab while it runs and you will see that no request carries your file.
How long does a 4K upscale take?
On a device with WebGPU, a short clip usually takes seconds to a couple of minutes. Without WebGPU the tool falls back to the CPU, which is much slower, and 4K is the heaviest target. Close other tabs, and trim long clips first.
Why is my 4K file so much bigger?
A 4K frame has four times the pixels of a 1080p frame. Depending on the engine and quality setting the output often runs at roughly 15 to 30 Mbps, so one minute can be a couple of hundred MB. Run it through the Video Compressor if you need a smaller file.
What happens if my video is already 4K?
Nothing is scaled down. The tool never reduces resolution in 4K mode, so a source that is already 3840x2160 or larger stays at its size.
Can I upscale vertical or portrait video to 4K?
Yes. In Resolution mode the target applies to the short side, and your aspect ratio is kept. A 1080x1920 phone video becomes 2160x3840.
Does it keep the audio?
Yes for MP4 output, and you can switch it off with Keep audio. On the fast engines, audio is re-attached afterwards, and for files over 150 MB it may be skipped, in which case the tool shows a note.
What are the file limits?
Up to 300 MB and 3 minutes per file, and up to 10 files per batch. For 4K, run 2 to 5 files at a time, because 4K uses a lot of memory. Use the Video Trimmer if a clip is too long.
Do I need a graphics card?
No, but it helps a lot. The page detects WebGPU automatically and uses your GPU when it can. If WebGPU is not available, or the GPU pass fails, it switches to a CPU engine and keeps going.
Does it work on iPhone and Android?
It can in modern mobile browsers, but 4K on a phone is slow and memory hungry. Use a laptop or desktop for anything beyond a short clip.
Can I get 8K?
No. The tool tops out at 4K (3840x2160) to keep processing stable in the browser.
More free video and image tools
Explore other tools that run entirely in your browser.
- Video UpscalerAll upscale options: 2x, 3x, 4x or 720p, 1080p, 2K.
- Video CompressorShrink the 4K result so it is easy to share.
- Video TrimmerCut the clip to 3 minutes or less before upscaling.
- Video EnhancerSharpen, denoise, and enhance video.
- Image UpscalerEnlarge photos up to 4x without blur.
- Video to GIFConvert your videos into high-quality GIFs.
Your videos never leave your device
There is no upload step and no server-side video handling. The video is decoded, upscaled and re-encoded in your browser using WebCodecs and, when available, WebGPU. Open the browser Network tab while upscaling and confirm that no request carries your file. Read how we keep it private.