Resize Video to 3840x2160

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MP4, MOV, WebM, or MKV to resize

Tip: paste a video file from clipboard (Ctrl/⌘+V).

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Settings are written to the URL as you change them. Nothing differs from the defaults yet.

Resize a video to 3840x2160, the 4K UHD frame.

Upscaling is interpolation

Scaling up invents pixels by reading between the ones that exist. No detail is recovered. The pixel count roughly quadruples from 1080p, the file grows in proportion, and any blocking or ringing already in the source is magnified along with the picture.

There are two honest reasons to do it anyway. A platform or client that rejects anything under 4K, and a platform whose 2160p encoding tier is funded better than its 1080p one, which can make the delivered stream look better even to viewers watching at 1080p.

Neither reason is “it will look sharper”. The tool says so when the target exceeds the source.

UHD is not DCI 4K

3840x2160 is UHD, the 16:9 consumer standard used by televisions, YouTube, and streaming services. DCI 4K is 4096x2160, slightly wider, and belongs to cinema delivery.

They are not interchangeable in a cinema pipeline. For DCI, type 4096 and 2160 on the full tool.

Export cost

Every frame is decoded, drawn at 8.3 megapixels, and encoded again. A 4K frame costs roughly four times what a 1080p frame does, so a 4K export usually runs slower than realtime and a long clip takes a while. Leave the tab open while it runs.

Frequently Asked Questions

Can I turn a 1080p video into a real 4K one?

No. Scaling up interpolates between existing pixels. Nothing is recovered, the file grows about four times in pixel count, and compression artifacts in the source get larger along with everything else.

Then why would anyone upscale to 4K?

To clear a hard requirement, or to reach a platform's 2160p encoding tier, which is funded more generously than 1080p. Both are real reasons. Neither makes the picture sharper.

Is 3840x2160 the same as DCI 4K?

No. 3840x2160 is UHD, the 16:9 consumer standard. DCI 4K is 4096x2160, slightly wider, and used in cinema delivery. Type the exact numbers on the full tool if you need DCI.

How long does a 4K export take?

Longer than the clip, on most machines. Every frame is decoded, drawn at 8.3 megapixels, and encoded again, and 4K costs roughly four times what 1080p does per frame.