GPT Image 2.5 Sunburstvs.Stable Diffusion 3.5 Medium

Which one is better?

In our own test, GPT Image 2.5 Sunburst leads. Stable Diffusion 3.5 Medium has no arena rating yet. Stable Diffusion 3.5 Medium has no API price.

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 Sunburst93 out of 100

Stable Diffusion 3.5 Medium: Product photography, first image from the fixed test run — Stable Diffusion 3.5 Medium13 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

Both models receive the same archived prompt in exactly one request, and the first result counts. 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 Medium: fal, requested 1024x1024, n=1, seed=provider random, estimated cost $0.020000, generated Nov 1, 2026, 9:17 PM. Source

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

GPT Image 2.5 Sunburst image SHA 256: 2bcd5e2358dbf9e2f11336ebf6c4a4a15e0a9a10261dd74378d40985ac68ec6d

Stable Diffusion 3.5 Medium image SHA 256: 6b8aa732e94479ad302904096c5031908141e4083ee099f080185aa04c2ea800

Infographic

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

Stable Diffusion 3.5 Medium: fal, requested 1024x1024, n=1, seed=provider random, estimated cost $0.020000, generated Nov 1, 2026, 9:17 PM. Source

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

GPT Image 2.5 Sunburst image SHA 256: 7dab94e5588be73aefe08f23f9d56ced4e2ddb2b29f754db41b057025cf34847

Stable Diffusion 3.5 Medium image SHA 256: 61b12e227431387098e51c6ce6d059be9d8df9c85263b994bee62602e2ddfd16

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 Medium: fal, requested 1024x1024, n=1, seed=provider random, estimated cost $0.020000, generated Nov 1, 2026, 9:16 PM. Source

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

GPT Image 2.5 Sunburst image SHA 256: c648276704e06f7925f2325e8ffff0d9d0a9bd6c5bb4866785abac92ce97ff9a

Stable Diffusion 3.5 Medium image SHA 256: 2412a20e61c118ce7ab7ff83e285b96eb32d5c0f1171cc769e153db6655b8f67

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 Medium: fal, requested 1024x1024, n=1, seed=provider random, estimated cost $0.020000, generated Nov 1, 2026, 9:16 PM. Source

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

GPT Image 2.5 Sunburst image SHA 256: fd6a3767ba8253869cb94d5346f025541dac924c2190df2c37b366b182986cf8

Stable Diffusion 3.5 Medium image SHA 256: bc854c3269ea8bada6f764545f4a09abedc110219018c09f2fa5708a14d9af7e

The numbers at a glance

Arena ratingfrom votes by users · higher is better

1,427

GPT Image 2.5 Sunburst

Rank 1 of 22

n/a

Stable Diffusion 3.5 Medium

not in the arena

GraduallyBenchour own rating, 0 to 100 · higher is better

GPT Image 2.5 Sunburst

Rank 4 of 74

Stable Diffusion 3.5 Medium

Rank 69 of 74

Price per imagedollars through the API · lower is better

$0.21

GPT Image 2.5 Sunburst

expensive

n/a

Stable Diffusion 3.5 Medium

no API price

Ranks among the 22 image models with an arena rating and the 74 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 Medium

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 1, 2026 · API prices from Oct 28, 2026 · Subscription database from Sep 29, 2026 (34 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 Medium
Ratings
Arena ratingfrom votes by users, higher is better	1,427	n/a
Arena rank	Rank 1 of 22	n/a
Arena votesmore votes, a safer rating	40,323	n/a
GraduallyBenchour own rating, 0 to 100	77	16
GraduallyBench by task
Typography and layoutLegible text, hierarchy, and composition	48	17
Product photographyMaterials, reflections, and fine details	93	13
Character and detailAnatomy, clothing, and spatial consistency	74	16
InfographicNumbers, labels, and visual organization	91	20
API price
Per imagelower is better	$0.21	n/a
100 images	$21.07	n/a
Profile
Released	Sep 8, 2026	Oct 29, 2024
Weightsopen means: runs locally	proprietary	open
Access	API	API, local
Parameters	not published	2.5 billion
Largest output	3,840 × 2,160 pixels	not consistently published
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 Medium model source (verified Nov 1, 2026)

Arena ratings by category

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

No shared arena score in the stored snapshot

The stored benchmark database contains no measurement for GPT Image 2.5 Sunburst and Stable Diffusion 3.5 Medium from the same arena and category. Older model versions are not used as substitutes.

Compare another matchup

First image modelSecond image model

More matchups

Compare GPT Image 2.5 Sunburst and Stable Diffusion 3.5 Medium with other important image models.

View the complete image model comparison

Same prompt, two images

The numbers at a glance

GPT Image 2.5 Sunburst

Stable Diffusion 3.5 Medium

All data side by side

Arena ratings by category

No shared arena score in the stored snapshot

Compare another matchup

Related image model comparisons