Convert an image to 4K

The 4K panel. Every chip shows the size your picture becomes and the factor; anything past 8× is refused with the largest size that is honest for that picture.

Everything happens on this device; the picture is never sent to a server.

• 4K from a small source is mostly arithmetic.At ×4 fifteen of every sixteen pixels are computed. Use Split and the 1:1 strip before you rely on it.
• Memory is the limit, not patience.A 4K result is 8.3 megapixels; 8K is 33.2. Older phones may refuse even 4K for a large source, and the bench says so before you press Save.

Is a 4K file from a 900 px photo really 4K?

It has 4K pixels. A 900 × 506 photo brought to 3,840 × 2,160 is ×4.27, so roughly nineteen in every twenty pixels were worked out rather than recorded. It will look like a smooth enlargement, not like a photo taken in 4K — the 1:1 strip shows exactly that.

Why won't it go to 8K on my phone?

8K is 7,680 × 4,320 — 33.2 megapixels. Phone browsers reliably hand back about 24 megapixels as one image, so the bench keeps 8K for desktop browsers, where the ceiling is 80 megapixels.

Why does it refuse some pictures?

Past 8× the bench stops. A 320 × 180 picture would need ×12 to reach 4K; the page says so and offers the largest honest target instead (2,560 × 1,440 for that picture).

Does my picture leave the device?

No. The 4K result is computed in this tab and saved by your browser.

• HD image converterFit a small picture to 1280 × 720 or 1920 × 1080 without cropping or stretching it.
• Four times overThe usual answer when a picture is close but not close enough. Opens at 4×.
• AI upscalingTwo trained models, downloaded once on request and run here. Invented detail, named as such.
• Increase image resolutionType the exact width, height or long edge; the bench shows the factor that results and whether it fits.