How do you convert 3840 × 2160 to 9:16?
Crop 1216 × 2160 → 2160 × 3840
To fill a 9:16 frame from 3840 × 2160, take the largest 9:16 region the source contains — 1216 × 2160 — and scale it to the 2160 × 3840 delivery size. That keeps 31.7% of the original picture. Padding instead of cropping keeps all of it, at 2160 × 1216 with bars of 1312 px top and bottom.
How that is worked out
crop = the largest target-ratio box inside the source
3840 × 2160 → 1216 × 2160 → 2160 × 3840
Worth knowing
- A crop keeps 31.7% of the source pixels. Everything that matters has to sit inside a 1216 px wide column of the original frame.
- Reaching 2160 × 3840 means scaling that crop up 1.78×, so the delivered file is softer than the source. Finishing from a 4K master removes the upscale.
- Padding instead keeps the whole picture at 2160 × 1216 inside the 2160 × 3840 frame, with bars of 1312 px top and bottom. On feeds that autoplay muted, bars read as a repost and cost reach.
- Both routes land on even pixel dimensions, which H.264 and H.265 require in 4:2:0. Where the exact ratio and an even number disagree, the 1216 × 2160 crop follows the even number — a fraction of a pixel is not worth a rejected encode.
Crop or pad 3840 × 2160 for 9:16
| Route | Pixels | The cost |
|---|---|---|
| Crop to fill | 1216 × 2160, scaled to 2160 × 3840 | 68.3% of the picture is cut away |
| Pad to fit | 2160 × 1216 inside 2160 × 3840 | Bars of 1312 px top and bottom |
Cropping trades picture for a full frame; padding trades screen for the whole picture. A third route — reframing shot by shot with keyframed position — keeps more than either, but no calculator can do it for you.
3840 × 2160 to every common ratio
| Target ratio | Crop | Delivery size | Picture kept |
|---|---|---|---|
| 9:16 — this page | 1216 × 2160 | 2160 × 3840 | 31.7% |
| 4:5 | 1728 × 2160 | 2160 × 2700 | 45.0% |
| 1:1 | 2160 × 2160 | 2160 × 2160 | 56.3% |
| 5:4 | 2700 × 2160 | 2700 × 2160 | 70.3% |
| 4:3 | 2880 × 2160 | 2880 × 2160 | 75.0% |
| 3:2 | 3240 × 2160 | 3240 × 2160 | 84.4% |
| 16:9 | 3840 × 2160 | 3840 × 2160 | 100.0% |
| 1.85:1 | 3840 × 2076 | 3840 × 2076 | 96.1% |
| 1.9:1 | 3840 × 2022 | 3840 × 2022 | 93.6% |
| 2:1 | 3840 × 1920 | 3840 × 1920 | 88.9% |
| 21:9 | 3840 × 1646 | 3840 × 1646 | 76.2% |
| 2.39:1 | 3840 × 1606 | 3840 × 1606 | 74.4% |
Need it for other values?
Scale width and height to 16:9, 9:16, 4:5, 2.39:1 or a custom ratio, with pixel dimensions at 1080p and 4K.