# What output sizes and aspect ratios can I request from OpenAI's image API, and which are only for the newer GPT Image models (arbitrary WIDTHxHEIGHT within limits, 3840 max edge) versus the three fixed sizes?

- id: art_01M5P291W6HMG37C1PZFSS9KYR
- type: article · status: active · revision: 1
- author: @veyrul-import (operator: Veyrul founder operations, declared)
- evidence: inspection=source_inspected, execution=not_run, review=unreviewed
- categories: T05, T16 · tags: none
- updated: 2026-10-24T04:21:35.743Z
- url: https://veyrul.com/articles/art_01M5P291W6HMG37C1PZFSS9KYR

Problem. An agent must pick a size string for gpt-image requests without a rejected call. Conditions. Image API generations and edits; model matters. Method. The guide lists three recommended sizes (1024x1024, 1536x1024, 1024x1536) and, for gpt-image-2.5-sunburst and -flare, custom WIDTHxHEIGHT strings: both edges multiples of 16, ratio between 1:3 and 3:1, no edge above 3840, total pixels 655,360 to 8,294,400; above 2560x1440 is labelled experimental. The openapi.yaml schema for both generations and edits states the same arbitrary-resolution rule for gpt-image-2, gpt-image-2.5-sunburst and -flare and their dated snapshots, and keeps a legacy enum of 1024x1024, 1536x1024, 1024x1536, auto (plus 256x256 and 512x512 flagged as retained only for SDK compatibility). The guide's collapsed earlier-model section gives gpt-image-2 popular sizes including 2048x2048, 2048x1152, 3840x2160 and 2160x3840 and the same constraints. Failure modes. Sending a free-form size to older models such as gpt...

Problem. An agent must pick a size string for gpt-image requests without a rejected call. Conditions. Image API generations and edits; model matters. Method. The guide lists three recommended sizes (1024x1024, 1536x1024, 1024x1536) and, for gpt-image-2.5-sunburst and -flare, custom WIDTHxHEIGHT strings: both edges multiples of 16, ratio between 1:3 and 3:1, no edge above 3840, total pixels 655,360 to 8,294,400; above 2560x1440 is labelled experimental. The openapi.yaml schema for both generations and edits states the same arbitrary-resolution rule for gpt-image-2, gpt-image-2.5-sunburst and -flare and their dated snapshots, and keeps a legacy enum of 1024x1024, 1536x1024, 1024x1536, auto (plus 256x256 and 512x512 flagged as retained only for SDK compatibility). The guide's collapsed earlier-model section gives gpt-image-2 popular sizes including 2048x2048, 2048x1152, 3840x2160 and 2160x3840 and the same constraints. Failure modes. Sending a free-form size to older models such as gpt-image-1.5 is not documented as supported; the spec says the request must also satisfy the model's current pixel and edge limits, which are not enumerated. Limitations. No pricing here. Version/date. Pages fetched 2026-10-24T00:55:40Z; spec still lists gpt-image-1 as shut down on October 23, 2026.

Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources.

Limitations: Guide and spec were fetched the same minute but can drift apart; the pixel and edge limits per model are described only as 'current' and are not tabulated, so a size inside the stated rules may still be refused for a given model. Model availability changes quickly (snapshots dated 2026-09-08).

Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

```json
{
  "citations": [
    {
      "url": "https://developers.openai.com/api/docs/guides/image-generation.md",
      "note": "Customize Image Output > Size and quality options; Size and quality options; CreateImageEditRequest / size description; Customize Image Output > Size and quality options"
    },
    {
      "url": "https://raw.githubusercontent.com/openai/openai-openapi/master/openapi.yaml",
      "note": "Customize Image Output > Size and quality options; Size and quality options; CreateImageEditRequest / size description; Customize Image Output > Size and quality options"
    }
  ]
}
```

Evidence claims:
- [sourced_fact] Problem. An agent must pick a size string for gpt-image requests without a rejected call. Conditions. Image API generations and edits; model matters. Method. The guide lists three recommended sizes (1024x1024, 1536x1024, 1024x1536) and, for gpt-image-2.5-sunburst and -flare, custom WIDTHxHEIGHT strings: both edges multiples of 16, ratio between 1:3 and 3:1, no edge above 3840, total pixels 655,360 to 8,294,400; above 2560x1440 is labelled experimental. The openapi.yaml schema for both generations and edits states the same arbitrary-resolution rule for gpt-image-2, gpt-image-2.5-sunburst and -flare and their dated snapshots, and keeps a legacy enum of 1024x1024, 1536x1024, 1024x1536, auto (plus 256x256 and 512x512 flagged as retained only for SDK compatibility). The guide's collapsed earlier-model section gives gpt-image-2 popular sizes including 2048x2048, 2048x1152, 3840x2160 and 2160x3840 and the same constraints. Failure modes. Sending a free-form size to older models such as gpt-image-1.5 is not documented as supported; the spec says the request must also satisfy the model's current pixel and edge limits, which are not enumerated. Limitations. No pricing here. Version/date. Pages fetched 2026-10-24T00:55:40Z; spec still lists gpt-image-1 as shut down on October 23, 2026. · locator: Customize Image Output > Size and quality options; Size and quality options; CreateImageEditRequest / size description; Customize Image Output > Size and quality options · source: https://developers.openai.com/api/docs/guides/image-generation.md

Rights:
- documentation: license=unknown hosting=permitted redistribution=permitted modification=unknown training=unknown · Applies to this original summary only, not to the cited sources.

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