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GPT Image 1.5vs.Nano Banana 2.1

Which one is better?

In our own test both are on par. Nano Banana 2.1 has no arena rating yet. Nano Banana 2.1 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
Nano Banana 2.1: Character and detail, first image from the fixed test run
Nano Banana 2.157 out of 100

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

Nano Banana 2.1: openrouter, aspect ratio 1:1, resolution 1K, n=1, seed=provider random, actual cost $0.036408, generated Nov 1, 2026, 9:40 PM. Source

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

GPT Image 1.5 image SHA 256: 0dff52ccd39400ac66ac8870c9ea937512ff1474688e70118688f420c38c2296

Nano Banana 2.1 image SHA 256: f89e3f52678670058ce0e1e9b0b5b6ec084e25a212491b5025e76d7525fb8707

Infographic

GPT Image 1.5: together, 1024x1024, n=1, seed=provider random, provider default steps, generated Aug 14, 2026, 12:17 PM. Source

Nano Banana 2.1: openrouter, aspect ratio 1:1, resolution 1K, n=1, seed=provider random, actual cost $0.036560, generated Nov 1, 2026, 9:40 PM. Source

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

GPT Image 1.5 image SHA 256: 1c9ff59c32621c8b48b002dacb0ae66487262280c7c0a5b3d6456c81b248ebe9

Nano Banana 2.1 image SHA 256: ce5c4b7af2575ccf9964cfeea2e4f0bb75cdad21aea29c4201e693fa307e435b

Product photography

GPT Image 1.5: together, 1024x1024, n=1, seed=provider random, provider default steps, generated Aug 14, 2026, 12:16 PM. Source

Nano Banana 2.1: openrouter, aspect ratio 1:1, resolution 1K, n=1, seed=provider random, actual cost $0.036546, generated Nov 1, 2026, 9:39 PM. Source

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

GPT Image 1.5 image SHA 256: 67cfa2f324447027ceb5f82e9446d40a1395b46ce425890a74606b4d97731cf6

Nano Banana 2.1 image SHA 256: 289b144f7d5348e9324d229e5508d5698c09035f2cbdea474845a84b852e859e

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

Nano Banana 2.1: openrouter, aspect ratio 1:1, resolution 1K, n=1, seed=provider random, actual cost $0.036497, generated Nov 1, 2026, 9:39 PM. Source

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

GPT Image 1.5 image SHA 256: 6a4cec86850fd371b65274198e2bf630b3cf36a096f9fb953d4bfe17c3222ebe

Nano Banana 2.1 image SHA 256: d27b58baa4115177a46fae2d71e258c5f4de9243fc66df93983ef6127df2f320

The numbers at a glance

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

GPT Image 1.5

Rank 13 of 21

n/a

Nano Banana 2.1

not in the arena

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

GPT Image 1.5

Rank 29 of 108

66

Nano Banana 2.1

Rank 36 of 108

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

GPT Image 1.5

expensive

n/a

Nano Banana 2.1

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.

Nano Banana 2.1

Subscription
At Google from €4.99 a month (Google AI Plus, with limited credits). Through other providers from €6.83 a month (Poe Basic, with limited points). 42 plans in Germany.
Via API
No API price known. Access: API, Web app.
Weights
unknown.

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 1.5Nano Banana 2.1
Ratings
Arena ratingfrom votes by users, higher is better1,236n/a
Arena rankRank 13 of 21n/a
Arena votesmore votes, a safer rating173,798n/a
GraduallyBenchour own rating, 0 to 1006866
GraduallyBench by task
Typography and layoutLegible text, hierarchy, and composition6072
Product photographyMaterials, reflections, and fine details5270
Character and detailAnatomy, clothing, and spatial consistency8957
InfographicNumbers, labels, and visual organization7264
API price
Per imagelower is better$0.13n/a
100 images$13.30n/a
Profile
ReleasedDecember 2025Oct 6, 2026
Weightsopen means: runs locallyproprietaryunknown
LifecycleMarked as deprecated by OpenAI; removed from the API on December 1, 2026no notice
AccessAPI, Web appAPI, Web app
Parametersnot publishednot published
Largest output1,536 × 1,024 pixelsnot consistently published
Plans in Germanynaming exactly this model4242

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) · Nano Banana 2.1 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 Nano Banana 2.1 from the same arena and category. Older model versions are not used as substitutes.

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