GPT Image 2.5 Sunburstvs.FLUX.2 Klein 4B
Which one is better?
In our own test, GPT Image 2.5 Sunburst leads. FLUX.2 Klein 4B has no arena rating yet. FLUX.2 Klein 4B has no API price.
Same prompt, two images
Same task, the first image of each. The task with the biggest difference is preselected.
Result for “Infographic”:GPT Image 2.5 Sunburst ahead
What the rating looks at: Numbers, labels, and visual organization.
“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
FLUX.2 Klein 4B: fal, requested 1024x1024, n=1, seed=707400387, Fal's published 4B text-to-image endpoint; default four inference steps, estimated cost $0.005000, generated Nov 1, 2026, 9:01 PM. Source
Protocol gradually-image-comparison-v1. Prompt SHA 256: 985a75b38642a9f0e5e0c0e0c67f1b7f67780d42bd2168fa24e9a7a7a94b0da6
GPT Image 2.5 Sunburst image SHA 256: 2bcd5e2358dbf9e2f11336ebf6c4a4a15e0a9a10261dd74378d40985ac68ec6d
FLUX.2 Klein 4B image SHA 256: 170cebb7cf75bc033a92371199812674f9cfa9641d5e9fb13947ccf892d4ed53
Infographic
GPT Image 2.5 Sunburst: openai, 1024x1024, quality high, n=1, generated Sep 28, 2026, 8:52 PM. Source
FLUX.2 Klein 4B: fal, requested 1024x1024, n=1, seed=290140178, Fal's published 4B text-to-image endpoint; default four inference steps, estimated cost $0.005000, generated Nov 1, 2026, 9:01 PM. Source
Protocol gradually-image-comparison-v1. Prompt SHA 256: ed65cb4e6a51e2336f8b149ad4cbb16e020f07d527ad94362e719d2dcf91d94f
GPT Image 2.5 Sunburst image SHA 256: 7dab94e5588be73aefe08f23f9d56ced4e2ddb2b29f754db41b057025cf34847
FLUX.2 Klein 4B image SHA 256: 42b729a5a72207b5a92464f3ecf1713459ab1b105c3041c14b75c7622630015e
Product photography
GPT Image 2.5 Sunburst: openai, 1024x1024, quality high, n=1, generated Sep 28, 2026, 8:51 PM. Source
FLUX.2 Klein 4B: fal, requested 1024x1024, n=1, seed=1254275381, Fal's published 4B text-to-image endpoint; default four inference steps, estimated cost $0.005000, generated Nov 1, 2026, 9:00 PM. Source
Protocol gradually-image-comparison-v1. Prompt SHA 256: c67fd71e91304458a2feef5c91efa8677260fab0c0099a29a2c52cb579f5b2f3
GPT Image 2.5 Sunburst image SHA 256: c648276704e06f7925f2325e8ffff0d9d0a9bd6c5bb4866785abac92ce97ff9a
FLUX.2 Klein 4B image SHA 256: 8fae4a7f6abb7467281c439dc93aa656031626f88c8a54f95f49850cbf045580
Typography and layout
GPT Image 2.5 Sunburst: openai, 1024x1024, quality high, n=1, generated Sep 28, 2026, 8:50 PM. Source
FLUX.2 Klein 4B: fal, requested 1024x1024, n=1, seed=1270698692, Fal's published 4B text-to-image endpoint; default four inference steps, estimated cost $0.005000, generated Nov 1, 2026, 9:00 PM. Source
Protocol gradually-image-comparison-v1. Prompt SHA 256: 2e012c3d14ee5dd02203a94f394ca80a5038cdebd6032b25a8b8a221f2255419
GPT Image 2.5 Sunburst image SHA 256: fd6a3767ba8253869cb94d5346f025541dac924c2190df2c37b366b182986cf8
FLUX.2 Klein 4B image SHA 256: 7c2c3e30c20c98e90033087b2b95b151bddc3252dd4aed7092fcbca4ae4ea96e
The numbers at a glance
GPT Image 2.5 Sunburst
Rank 1 of 22
FLUX.2 Klein 4B
not in the arena
GPT Image 2.5 Sunburst
Rank 4 of 74
FLUX.2 Klein 4B
Rank 55 of 74
GPT Image 2.5 Sunburst
expensive
FLUX.2 Klein 4B
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.
FLUX.2 Klein 4B
- Subscription
- No Black Forest Labs subscription includes this model. Through other providers from €6.83 a month (Poe Basic, with limited points). 12 plans in Germany.
- 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 | FLUX.2 Klein 4B |
|---|---|---|
| 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 | 37 |
| GraduallyBench by task | ||
| Typography and layoutLegible text, hierarchy, and composition | 48 | 21 |
| Product photographyMaterials, reflections, and fine details | 93 | 54 |
| Character and detailAnatomy, clothing, and spatial consistency | 74 | 53 |
| InfographicNumbers, labels, and visual organization | 91 | 19 |
| API price | ||
| Per imagelower is better | $0.21 | n/a |
| 100 images | $21.07 | n/a |
| Profile | ||
| Released | Sep 8, 2026 | n/a |
| Weightsopen means: runs locally | proprietary | open |
| Access | API | API, local |
| Parameters | not published | 4 billion |
| Largest output | 3,840 × 2,160 pixels | not consistently published |
| Plans in Germanynaming exactly this model | 62 | 12 |
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) · FLUX.2 Klein 4B 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 FLUX.2 Klein 4B from the same arena and category. Older model versions are not used as substitutes.
Compare another matchup
More matchups
Related image model comparisons
Compare GPT Image 2.5 Sunburst and FLUX.2 Klein 4B with other important image models.