GPT Image 1.5vs.Z-Image Base
Which one is better?
In our own test, GPT Image 1.5 leads. Z-Image Base has no arena rating yet. Z-Image Base has no API price.
Test images
Same task, the first image of each. The task with the biggest difference is preselected.
Result for “Infographic”:GPT Image 1.5 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
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
Z-Image Base: fal, requested 1024x1024, n=1, seed=1788591829, estimated cost $0.020000, generated Nov 1, 2026, 9:35 PM. Source
Protocol gradually-image-comparison-v1. Prompt SHA 256: 985a75b38642a9f0e5e0c0e0c67f1b7f67780d42bd2168fa24e9a7a7a94b0da6
GPT Image 1.5 image SHA 256: 0dff52ccd39400ac66ac8870c9ea937512ff1474688e70118688f420c38c2296
Z-Image Base image SHA 256: 7a9c8b160230e302e618ad99ed1047d36b66bdc759d8455d0479048c442cdf75
Infographic
GPT Image 1.5: together, 1024x1024, n=1, seed=provider random, provider default steps, generated Aug 14, 2026, 12:17 PM. Source
Z-Image Base: fal, requested 1024x1024, n=1, seed=2013338091, estimated cost $0.020000, generated Nov 1, 2026, 9:35 PM. Source
Protocol gradually-image-comparison-v1. Prompt SHA 256: ed65cb4e6a51e2336f8b149ad4cbb16e020f07d527ad94362e719d2dcf91d94f
GPT Image 1.5 image SHA 256: 1c9ff59c32621c8b48b002dacb0ae66487262280c7c0a5b3d6456c81b248ebe9
Z-Image Base image SHA 256: b306143deb4d133e60ff4840e5fb8271d445f5a4944b98e89346763d84a19d30
Product photography
GPT Image 1.5: together, 1024x1024, n=1, seed=provider random, provider default steps, generated Aug 14, 2026, 12:16 PM. Source
Z-Image Base: fal, requested 1024x1024, n=1, seed=1140297503, estimated cost $0.020000, generated Nov 1, 2026, 9:35 PM. Source
Protocol gradually-image-comparison-v1. Prompt SHA 256: c67fd71e91304458a2feef5c91efa8677260fab0c0099a29a2c52cb579f5b2f3
GPT Image 1.5 image SHA 256: 67cfa2f324447027ceb5f82e9446d40a1395b46ce425890a74606b4d97731cf6
Z-Image Base image SHA 256: 11b631f154a0ddff86df21d6d8ffab0d208d51df894f3563dd6818d20b450aae
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
Z-Image Base: fal, requested 1024x1024, n=1, seed=194884257, estimated cost $0.010486, generated Nov 1, 2026, 9:20 PM. Source
Protocol gradually-image-comparison-v1. Prompt SHA 256: 2e012c3d14ee5dd02203a94f394ca80a5038cdebd6032b25a8b8a221f2255419
GPT Image 1.5 image SHA 256: 6a4cec86850fd371b65274198e2bf630b3cf36a096f9fb953d4bfe17c3222ebe
Z-Image Base image SHA 256: 62dbb49a07e3efe0f82ae9051fac20fce00a8f82b57ebe37a526b5176523c84f
The numbers at a glance
GPT Image 1.5
Rank 13 of 21
Z-Image Base
not in the arena
GPT Image 1.5
Rank 29 of 108
Z-Image Base
Rank 74 of 108
GPT Image 1.5
expensive
Z-Image Base
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.
Z-Image Base
- Subscription
- n/a No plan in Germany names exactly this model.
- Via API
- No API price known. Access: 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.
| Kennzahl | GPT Image 1.5 | Z-Image Base |
|---|---|---|
| Ratings | ||
| Arena ratingfrom votes by users, higher is better | 1,236 | n/a |
| Arena rank | Rank 13 of 21 | n/a |
| Arena votesmore votes, a safer rating | 173,798 | n/a |
| GraduallyBenchour own rating, 0 to 100 | 68 | 37 |
| GraduallyBench by task | ||
| Typography and layoutLegible text, hierarchy, and composition | 60 | 33 |
| Product photographyMaterials, reflections, and fine details | 52 | 22 |
| Character and detailAnatomy, clothing, and spatial consistency | 89 | 71 |
| InfographicNumbers, labels, and visual organization | 72 | 24 |
| API price | ||
| Per imagelower is better | $0.13 | n/a |
| 100 images | $13.30 | n/a |
| Profile | ||
| Released | December 2025 | Jan 27, 2026 |
| Weightsopen means: runs locally | proprietary | open |
| Lifecycle | Marked as deprecated by OpenAI; removed from the API on December 1, 2026 | no notice |
| Access | API, Web app | local |
| Parameters | not published | 6 billion |
| Largest output | 1,536 × 1,024 pixels | not consistently published |
| Plans in Germanynaming exactly this model | 42 | n/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) · Z-Image Base 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 1.5 and Z-Image Base from the same arena and category. Older model versions are not used as substitutes.
More comparisons
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