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GPT Image 1.5vs.Stable Diffusion 3.5 Large

Which one is better?

GPT Image 1.5 leads in both ratings: in our own test and in the arena. Both are in the lower half there, though. 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 1.5: Character and detail, first image from the fixed test run
GPT Image 1.589 out of 100
Stable Diffusion 3.5 Large: Character and detail, first image from the fixed test run
Stable Diffusion 3.5 Large23 out of 100

Result for “Character and detail”:GPT Image 1.5 ahead

Prompt given to both modelsCreate a square cinematic full-body portrait of a fictional bicycle courier waiting under a transparent umbrella at a rainy tram stop in Hamburg at blue hour. She wears a mustard raincoat, navy trousers, red sneakers, a silver helmet, and carries a teal messenger bag. Keep both hands visible, render the bicycle correctly, use realistic wet-street reflections, and include no readable brand names.

What the rating looks at: Anatomy, clothing, and spatial consistency.

“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 1.5: together, 1024x1024, n=1, seed=provider random, provider default steps, generated Aug 14, 2026, 12:17 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 1.5 image SHA 256: 0dff52ccd39400ac66ac8870c9ea937512ff1474688e70118688f420c38c2296

Stable Diffusion 3.5 Large image SHA 256: e748006fe56e442ad347e3f994f18b86ee1739f20dcee063aa7a03ee710c5d54

Infographic

GPT Image 1.5: together, 1024x1024, n=1, seed=provider random, provider default steps, generated Aug 14, 2026, 12:17 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 1.5 image SHA 256: 1c9ff59c32621c8b48b002dacb0ae66487262280c7c0a5b3d6456c81b248ebe9

Stable Diffusion 3.5 Large image SHA 256: 4eb0fd741ef42e6d3fee4b1280cdfb098a0a04009b139051963895892e349f1e

Product photography

GPT Image 1.5: together, 1024x1024, n=1, seed=provider random, provider default steps, generated Aug 14, 2026, 12:16 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 1.5 image SHA 256: 67cfa2f324447027ceb5f82e9446d40a1395b46ce425890a74606b4d97731cf6

Stable Diffusion 3.5 Large image SHA 256: ea9a7401dee8859ec2cb96af9f7ca29a177ef2202f52f629d8ce9f5839bd4061

Typography and layout

GPT Image 1.5: together, 1024x1024, n=1, seed=provider random, provider default steps, generated Aug 14, 2026, 1:59 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 1.5 image SHA 256: 6a4cec86850fd371b65274198e2bf630b3cf36a096f9fb953d4bfe17c3222ebe

Stable Diffusion 3.5 Large image SHA 256: e2994b1883a245b1c8c447957d121ea89d93aafff149029aa4e8507dbb769f9a

The numbers at a glance

Arena ratingfrom votes by users · higher is better
1,236

GPT Image 1.5

Rank 13 of 21

938

Stable Diffusion 3.5 Large

Rank 21 of 21

GraduallyBenchour own rating, 0 to 100 · higher is better
68

GPT Image 1.5

Rank 29 of 108

27

Stable Diffusion 3.5 Large

Rank 87 of 108

Price per imagedollars through the API · lower is better
$0.13

GPT Image 1.5

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 1.5

Subscription
No OpenAI subscription includes this model. Through other providers from ≈ €6.36 a month (ElevenLabs Starter, with limited credits). 42 plans in Germany.
Via API
$0.13 per image, 100 images $13.30.

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 Nov 6, 2026 · GraduallyBench from Nov 3, 2026 · API prices from Nov 6, 2026 · Subscription database from Sep 29, 2026 (38 days old)

All data side by side

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

KennzahlGPT Image 1.5Stable Diffusion 3.5 Large
Ratings
Arena ratingfrom votes by users, higher is better1,236938
Arena rankRank 13 of 21Rank 21 of 21
Arena votesmore votes, a safer rating173,79823,396
GraduallyBenchour own rating, 0 to 1006827
GraduallyBench by task
Typography and layoutLegible text, hierarchy, and composition6031
Product photographyMaterials, reflections, and fine details5217
Character and detailAnatomy, clothing, and spatial consistency8923
InfographicNumbers, labels, and visual organization7239
API price
Per imagelower is better$0.13n/a
100 images$13.30n/a
Profile
ReleasedDecember 2025Oct 22, 2024
Weightsopen means: runs locallyproprietaryopen
LifecycleMarked as deprecated by OpenAI; removed from the API on December 1, 2026no notice
AccessAPI, Web appAPI, local
Parametersnot published8.1 billion
Largest output1,536 × 1,024 pixels1 Megapixel
Plans in Germanynaming exactly this model42n/a

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

Sources: GPT Image 1.5 model source, status source (verified Aug 15, 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 1.5Stable Diffusion 3.5 Large
Text to Image: 3D modelingGPT Image 1.5: 1,218Stable Diffusion 3.5 Large: 963GPT Image 1.5 ahead
Text to Image: ArtGPT Image 1.5: 1,225Stable Diffusion 3.5 Large: 997GPT Image 1.5 ahead
Text to Image: CartoonGPT Image 1.5: 1,244Stable Diffusion 3.5 Large: 945GPT Image 1.5 ahead
Text to Image: Commercial designGPT Image 1.5: 1,238Stable Diffusion 3.5 Large: 937GPT Image 1.5 ahead
Text to Image: OverallGPT Image 1.5: 1,236Stable Diffusion 3.5 Large: 938GPT Image 1.5 ahead
Text to Image: PhotorealismGPT Image 1.5: 1,247Stable Diffusion 3.5 Large: 928GPT Image 1.5 ahead
Text to Image: PortraitsGPT Image 1.5: 1,259Stable Diffusion 3.5 Large: 942GPT Image 1.5 ahead
Text to Image: Text renderingGPT Image 1.5: 1,251Stable Diffusion 3.5 Large: 921GPT Image 1.5 ahead

LMArena from Nov 6, 2026

All individual values with sources
RatingGPT Image 1.5Stable Diffusion 3.5 LargeSource
Text to Image: 3D modeling1,218963LMArenaRetrieved Nov 6, 2026
Text to Image: Art1,225997LMArenaRetrieved Nov 6, 2026
Text to Image: Cartoon1,244945LMArenaRetrieved Nov 6, 2026
Text to Image: Commercial design1,238937LMArenaRetrieved Nov 6, 2026
Text to Image: Overall1,236938LMArenaRetrieved Nov 6, 2026
Text to Image: Photorealism1,247928LMArenaRetrieved Nov 6, 2026
Text to Image: Portraits1,259942LMArenaRetrieved Nov 6, 2026
Text to Image: Text rendering1,251921LMArenaRetrieved Nov 6, 2026

Published specialist tests

This pair shares 7 results from published research benchmarks.

Specialist testspublished research benchmarks · higher is betterGPT Image 1.5Stable Diffusion 3.5 Large
WISE Verified overallGPT Image 1.5: 83%Stable Diffusion 3.5 Large: 40%GPT Image 1.5 ahead
WISE cultureGPT Image 1.5: 89%Stable Diffusion 3.5 Large: 49%GPT Image 1.5 ahead
WISE timeGPT Image 1.5: 69%Stable Diffusion 3.5 Large: 41%GPT Image 1.5 ahead
WISE spaceGPT Image 1.5: 88%Stable Diffusion 3.5 Large: 44%GPT Image 1.5 ahead
WISE biologyGPT Image 1.5: 80%Stable Diffusion 3.5 Large: 30%GPT Image 1.5 ahead
WISE physicsGPT Image 1.5: 76%Stable Diffusion 3.5 Large: 38%GPT Image 1.5 ahead
WISE chemistryGPT Image 1.5: 78%Stable Diffusion 3.5 Large: 21%GPT Image 1.5 ahead

WISE Verified from Aug 26, 2026

All individual values with sources
RatingGPT Image 1.5Stable Diffusion 3.5 LargeSource
WISE Verified overall83%40%WISE VerifiedRetrieved Aug 26, 2026
WISE culture89%49%WISE VerifiedRetrieved Aug 26, 2026
WISE time69%41%WISE VerifiedRetrieved Aug 26, 2026
WISE space88%44%WISE VerifiedRetrieved Aug 26, 2026
WISE biology80%30%WISE VerifiedRetrieved Aug 26, 2026
WISE physics76%38%WISE VerifiedRetrieved Aug 26, 2026
WISE chemistry78%21%WISE VerifiedRetrieved Aug 26, 2026

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