How to upscale a 720p video to 4K

1. Check that the original fits the browser workflow

Use the best available source, no longer than 30 seconds, no larger than 100 MB and no greater than 921,600 pixels per frame. A 1280 × 720 progressive clip fits; a 1920 × 1080 clip does not. If your original exceeds these limits, choose a desktop workflow rather than throwing away detail just to fit a browser tool.

• Keep an untouched copy and note the source width, height and frame rate.
• Preview the original and listen to its audio before processing.
• Choose a sample with a face or text, a textured area and some movement.

2. Choose 3× for a 1280 × 720 source

In the 4K tool, select 3× and confirm that the result is 3840 × 2160. This is the model’s native scale and exactly matches the 8,294,400-pixel video cap. A 720 × 1280 portrait source becomes 2160 × 3840. Do not select 4× for a full 720p source: it exceeds the output cap.

3. Preserve the source ratio and check smaller-source math

A scale choice does not crop the frame or force it onto a 16:9 canvas. A 4:3 video remains 4:3. Likewise, 640 × 360 at the maximum 4× scale becomes 2560 × 1440, not UHD 4K. If you need exact delivery dimensions beyond these choices, use an editor that supports a custom canvas instead of repeatedly upscaling the same file.

4. Generate the first-frame AI preview and inspect detail

Move the comparison slider over eyes, hair, diagonal edges, lettering and repeating patterns. Look for a clearer appearance without distorted contours or invented-looking symbols. The preview contains only the first frame. If that frame is a fade or black title card, it cannot tell you much about the rest of the video; judge a representative exported sample before deciding.

5. Export the clip and watch the motion

Keep the browser tab visible while it processes every frame. Local AI can take much longer than the clip’s playback time. Watch the downloaded video at your intended display size and at full resolution. Details that seem convincing in a still may flicker between frames. If a 4K export fails, try a smaller scale or another format offered by the workspace.

6. Verify the saved file before publishing

Check that the file reports 3840 × 2160 for the landscape example, plays from start to finish and retains the expected primary audio. Open it in the player or editor you will actually use. Compare it with the original at the same viewing size and keep both files. The 4K dimensions describe the output canvas; they do not certify authentic recovery of missing source detail.