> ## Documentation Index
> Fetch the complete documentation index at: https://docs.dimilinks.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Sizes and resolution

> Aspect ratios, pixel dimensions, and resolution tiers supported by gpt-image-2.

We recommend separating the aspect ratio and resolution into two parameters:

```json theme={null}
{
  "size": "16:9",
  "resolution": "2k"
}
```

You can also pass exact pixel dimensions:

```json theme={null}
{
  "size": "3840x2160"
}
```

## Recommended options

* Aspect ratios: `1:1`, `3:2`, `2:3`, `4:3`, `3:4`, `16:9`, `9:16`, `21:9`, `9:21`.
* Resolutions: `1k`, `2k`, `4k`.
* Defaults: `size=1:1`, `resolution=2k`.
* Expose exact `WxH` pixels only in an advanced mode.

## Resolution fields

We recommend using only `resolution`. The following aliases are also supported:

| Field        | Example            | Description                                                            |
| ------------ | ------------------ | ---------------------------------------------------------------------- |
| `resolution` | `1k` / `2k` / `4k` | Recommended field.                                                     |
| `image_size` | `2k`               | Compatibility alias.                                                   |
| `scale`      | `4k`               | Compatibility alias.                                                   |
| `upscale`    | `2k` / `4k`        | Compatibility alias.                                                   |
| `quality`    | `2k` / `4k`        | Legacy compatibility; no longer recommended for expressing resolution. |

## Dimension mapping

When `size` is an aspect ratio, the service maps it to exact pixel dimensions. Width and height are aligned to 16 pixels. The 4K tier stays within an approximate `3840x2160` pixel budget, so square 4K output is `2880x2880`, not `3840x3840`.

| `size`         |          1K |          2K |          4K |
| -------------- | ----------: | ----------: | ----------: |
| `auto` / `1:1` | `1024x1024` | `2048x2048` | `2880x2880` |
| `3:2`          |  `1008x672` | `2016x1344` | `3504x2336` |
| `2:3`          |  `672x1008` | `1344x2016` | `2336x3504` |
| `4:3`          |  `1024x768` | `2048x1536` | `3264x2448` |
| `3:4`          |  `768x1024` | `1536x2048` | `2448x3264` |
| `5:4`          |   `960x768` | `2000x1600` | `3200x2560` |
| `4:5`          |   `768x960` | `1600x2000` | `2560x3200` |
| `16:9`         |  `1024x576` | `2048x1152` | `3840x2160` |
| `9:16`         |  `576x1024` | `1152x2048` | `2160x3840` |
| `2:1`          |  `1024x512` | `2048x1024` | `3840x1920` |
| `1:2`          |  `512x1024` | `1024x2048` | `1920x3840` |
| `21:9`         |  `1008x432` |  `2016x864` | `3696x1584` |
| `9:21`         |  `432x1008` |  `864x2016` | `1584x3696` |

## Images per request

The maximum `n` depends on the resolution tier:

| Tier | Maximum `n` per request |      Typical time |
| ---- | ----------------------: | ----------------: |
| `1k` |                       1 |  About 60 seconds |
| `2k` |                       4 | About 120 seconds |
| `4k` |                       4 | About 180 seconds |

## Recommendations

* Use `2k` by default for the best balance in most products.
* `4k` takes longer to generate; expose it under advanced options.
* `1k` can generate only one image per request and is suitable for previews or low-cost batches.
* If users care only about social-media formats, show aspect ratios first instead of asking them to enter pixels.