GPT Image 2.5 Sunburstvs.Stable Diffusion 3.5 Large

Which one is better?

GPT Image 2.5 Sunburst leads in both ratings: in our own test and in the arena. Stable Diffusion 3.5 Large has no API price.

Test images

Same task, the first image of each. The task with the biggest difference is preselected.

GPT Image 2.5 Sunburst: Product photography, first image from the fixed test run — GPT Image 2.5 Sunburst87 out of 100

Stable Diffusion 3.5 Large: Product photography, first image from the fixed test run — Stable Diffusion 3.5 Large17 out of 100

Result for “Product photography”:GPT Image 2.5 Sunburst ahead

Prompt given to both modelsCreate a square premium product photograph of a brushed titanium wristwatch standing upright on dark green marble. The watch has a cream dial, thin black hands set to 10:10, twelve distinct hour markers, a realistic crown, and a dark brown leather strap. Soft window light from the left, controlled reflections, shallow depth of field, no text, no logo, no extra objects.

What the rating looks at: Materials, reflections, and fine details.

“Ahead”: better in all three rating rounds. “Slightly ahead”: a higher value, but not in every round.

Test protocol of the images

Each test attempt uses the same archived prompt and one request. The first output of that attempt counts. Repeats after technical test failures are disclosed for the affected images. Files are normalized to 1,024 × 1,024 pixels without cropping. Provider resolution, randomness, quality tier and prompt processing can still differ. The images are a practical visual test, not a reconstruction of the arena configuration.

Character and detail

GPT Image 2.5 Sunburst: openai, 1024x1024, quality high, n=1, generated Sep 28, 2026, 8:51 PM. Source

Stable Diffusion 3.5 Large: fal, requested 1024x1024, n=1, seed=7087247023770270000, estimated cost $0.068157, generated Aug 14, 2026, 2:37 PM. Source

Protocol gradually-image-comparison-v1. Prompt SHA 256: 985a75b38642a9f0e5e0c0e0c67f1b7f67780d42bd2168fa24e9a7a7a94b0da6

GPT Image 2.5 Sunburst image SHA 256: 2bcd5e2358dbf9e2f11336ebf6c4a4a15e0a9a10261dd74378d40985ac68ec6d

Stable Diffusion 3.5 Large image SHA 256: e748006fe56e442ad347e3f994f18b86ee1739f20dcee063aa7a03ee710c5d54

Infographic

GPT Image 2.5 Sunburst: openai, 1024x1024, quality high, n=1, generated Sep 28, 2026, 8:52 PM. Source

Stable Diffusion 3.5 Large: fal, requested 1024x1024, n=1, seed=12166653711354006000, estimated cost $0.068157, generated Aug 14, 2026, 2:37 PM. Source

Protocol gradually-image-comparison-v1. Prompt SHA 256: ed65cb4e6a51e2336f8b149ad4cbb16e020f07d527ad94362e719d2dcf91d94f

GPT Image 2.5 Sunburst image SHA 256: 7dab94e5588be73aefe08f23f9d56ced4e2ddb2b29f754db41b057025cf34847

Stable Diffusion 3.5 Large image SHA 256: 4eb0fd741ef42e6d3fee4b1280cdfb098a0a04009b139051963895892e349f1e

Product photography

GPT Image 2.5 Sunburst: openai, 1024x1024, quality high, n=1, generated Sep 28, 2026, 8:51 PM. Source

Stable Diffusion 3.5 Large: fal, requested 1024x1024, n=1, seed=13346308312015933000, estimated cost $0.068157, generated Aug 14, 2026, 2:37 PM. Source

Protocol gradually-image-comparison-v1. Prompt SHA 256: c67fd71e91304458a2feef5c91efa8677260fab0c0099a29a2c52cb579f5b2f3

GPT Image 2.5 Sunburst image SHA 256: c648276704e06f7925f2325e8ffff0d9d0a9bd6c5bb4866785abac92ce97ff9a

Stable Diffusion 3.5 Large image SHA 256: ea9a7401dee8859ec2cb96af9f7ca29a177ef2202f52f629d8ce9f5839bd4061

Typography and layout

GPT Image 2.5 Sunburst: openai, 1024x1024, quality high, n=1, generated Sep 28, 2026, 8:50 PM. Source

Stable Diffusion 3.5 Large: fal, requested 1024x1024, n=1, seed=16632333557910893000, estimated cost $0.068157, generated Aug 14, 2026, 2:37 PM. Source

Protocol gradually-image-comparison-v1. Prompt SHA 256: 2e012c3d14ee5dd02203a94f394ca80a5038cdebd6032b25a8b8a221f2255419

GPT Image 2.5 Sunburst image SHA 256: fd6a3767ba8253869cb94d5346f025541dac924c2190df2c37b366b182986cf8

Stable Diffusion 3.5 Large image SHA 256: e2994b1883a245b1c8c447957d121ea89d93aafff149029aa4e8507dbb769f9a

The numbers at a glance

Arena ratingfrom votes by users · higher is better

1,427

GPT Image 2.5 Sunburst

Rank 1 of 21

938

Stable Diffusion 3.5 Large

Rank 21 of 21

GraduallyBenchour own rating, 0 to 100 · higher is better

GPT Image 2.5 Sunburst

Rank 8 of 108

Stable Diffusion 3.5 Large

Rank 87 of 108

Price per imagedollars through the API · lower is better

$0.21

GPT Image 2.5 Sunburst

expensive

n/a

Stable Diffusion 3.5 Large

no API price

Ranks among the 21 image models with an arena rating and the 108 with a GraduallyBench run; prices compared with 28 models with an API price.

GPT Image 2.5 Sunburst

Subscription: No OpenAI subscription includes this model. Through other providers from ≈ €6.39 a month (ElevenLabs Starter, with limited credits). 62 plans in Germany.
Via API: $0.21 per image, 100 images $21.07.

Stable Diffusion 3.5 Large

Subscription: n/a No plan in Germany names exactly this model.
Via API: No API price known. Access: API, local.
License: Open weights.

Subscriptions only count plans that name exactly this model. Subscription prices include VAT, API prices are in dollars.

Arena rating (LMArena) from Oct 28, 2026 · GraduallyBench from Nov 3, 2026 · API prices from Nov 3, 2026 · Subscription database from Sep 29, 2026 (35 days old)

All data side by side

The better value is bold. For ratings only when the gap is clear.

Kennzahl	GPT Image 2.5 Sunburst	Stable Diffusion 3.5 Large
Ratings
Arena ratingfrom votes by users, higher is better	1,427	938
Arena rank	Rank 1 of 21	Rank 21 of 21
Arena votesmore votes, a safer rating	40,323	23,396
GraduallyBenchour own rating, 0 to 100	75	27
GraduallyBench by task
Typography and layoutLegible text, hierarchy, and composition	54	31
Product photographyMaterials, reflections, and fine details	87	17
Character and detailAnatomy, clothing, and spatial consistency	64	23
InfographicNumbers, labels, and visual organization	97	39
API price
Per imagelower is better	$0.21	n/a
100 images	$21.07	n/a
Profile
Released	Sep 8, 2026	Oct 22, 2024
Weightsopen means: runs locally	proprietary	open
Access	API	API, local
Parameters	not published	8.1 billion
Largest output	3,840 × 2,160 pixels	1 Megapixel
Plans in Germanynaming exactly this model	62	n/a

API prices for one image at 1,024 × 1,024 pixels according to Artificial Analysis.

Sources: GPT Image 2.5 Sunburst model source (verified Sep 24, 2026) · Stable Diffusion 3.5 Large model source (verified Aug 15, 2026)

Arena ratings by category

From blind votes on LMArena. “Ahead” means the lead is clear.

Arena rating per categoryfrom votes by users · higher is betterGPT Image 2.5 SunburstStable Diffusion 3.5 Large

Text to Image: 3D modeling1,416963ahead

Text to Image: Art1,409997ahead

Text to Image: Cartoon1,456945ahead

Text to Image: Commercial design1,419937ahead

Text to Image: Overall1,427938ahead

Text to Image: Photorealism1,433928ahead

Text to Image: Portraits1,461942ahead

Text to Image: Text rendering1,466921ahead

LMArena from Oct 28, 2026

All individual values with sources

Rating	GPT Image 2.5 Sunburst	Stable Diffusion 3.5 Large	Source
Text to Image: 3D modeling	1,416	963	LMArenaRetrieved Oct 28, 2026
Text to Image: Art	1,409	997	LMArenaRetrieved Oct 28, 2026
Text to Image: Cartoon	1,456	945	LMArenaRetrieved Oct 28, 2026
Text to Image: Commercial design	1,419	937	LMArenaRetrieved Oct 28, 2026
Text to Image: Overall	1,427	938	LMArenaRetrieved Oct 28, 2026
Text to Image: Photorealism	1,433	928	LMArenaRetrieved Oct 28, 2026
Text to Image: Portraits	1,461	942	LMArenaRetrieved Oct 28, 2026
Text to Image: Text rendering	1,466	921	LMArenaRetrieved Oct 28, 2026

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Predecessor and successor

PredecessorGPT Image 2.5 Sunburst vs. GPT Image 2Predecessor of GPT Image 2.5 Sunburst
GPT Image 2.5 Sunburst has no successor yet
Stable Diffusion 3.5 Large has no successor yet

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