For most teams, Nano Banana 2 should be the default. Move the same job to Nano Banana Pro only when text, complex composition, identity or brand consistency, or final-delivery review fails. In the API, that means gemini-3.1-flash-image first and gemini-3-pro-image as a conditional premium route.
That answer is more useful than calling 2 “faster” and Pro “higher quality.” It lets you include discarded drafts, retries, review time, and the cost of a failed final asset. It also avoids a naming trap: Nano Banana 2 Lite is a separate gemini-3.1-flash-lite-image model limited to 1K. This page compares Nano Banana 2 with Nano Banana Pro.
The decision starts with the job you need to ship, then uses an observable failure—not a model badge—to trigger Pro.
| Workload | Start with | Escalate when |
|---|---|---|
| Concepts, social variants, bulk generation, iterative edits | Nano Banana 2 | A near-final candidate still fails text, layout, or consistency checks |
| Menus, price cards, dense infographics, text-heavy posters | Nano Banana Pro | Use 2 first only if you are still discarding directions |
| Product images, characters, and branded campaign assets | Nano Banana 2 | Product details, identity, style, or local edits keep drifting |
| A general image feature in an API product | Nano Banana 2 | A valuable final asset hits a documented acceptance failure |
Use the current GA model IDs before comparing anything else
Google released the GA models on May 28, 2026 and shut down the corresponding previews on June 25. Current integrations should use:
- Nano Banana 2:
gemini-3.1-flash-image - Nano Banana Pro:
gemini-3-pro-image - Separate 1K-only Nano Banana 2 Lite:
gemini-3.1-flash-lite-image
The Gemini API release notes confirm the GA and preview dates, while the image generation guide documents the current model family. If your code still calls gemini-3.1-flash-image-preview or gemini-3-pro-image-preview, migrate the ID first. A retired endpoint error tells you nothing about current image quality or speed.
Gemini Apps uses a different selection flow. Google’s Gemini Apps image help says eligible paid subscribers can generate with Nano Banana 2 or 2 Lite, then choose Redo with Pro from the result menu. Apps is a result-level redo; the API is explicit model routing. Subscription access and API usage pricing are separate contracts.
Price the resolution you will actually ship
Only the 1K tier is exactly half price. The 2K and 4K gaps are different, so price the delivered size rather than repeating a headline percentage.
As of August 5, 2026, the official Gemini Developer API pricing page lists these Standard image-output equivalents:
| Output size | Nano Banana 2 | Nano Banana Pro | NB2 image-output saving |
|---|---|---|---|
| 0.5K | $0.045 | Not offered | — |
| 1K | $0.067 | $0.134 | 50.0% |
| 2K | $0.101 | $0.134 | About 24.6% |
| 4K | $0.151 | $0.240 | About 37.1% |
“Nano Banana 2 costs half as much as Pro” is accurate at 1K, not across the table. Pro’s Standard 1K and 2K image outputs have the same equivalent price. NB2 adds a lower 0.5K option and steps up at each resolution.
These numbers do not represent a complete invoice. They exclude input, text/thinking output, grounding, Batch/Flex/Priority differences, taxes, gateway pricing, retries, and human repair.
For a simple worked example, 100 accepted 2K images with every request succeeding on the first attempt would have these base image-output amounts:
- Nano Banana 2:
100 × $0.101 = $10.10 - Nano Banana Pro:
100 × $0.134 = $13.40
A production team should then calculate:
accepted-image cost = (total API spend + rework cost) / accepted images
If NB2 repeatedly misspells labels or disturbs an approved layout, Pro can have the lower accepted-image cost despite its higher sticker price. If you are exploring 40 concepts and keeping eight, paying the premium on all 40 usually increases the cost of ideas you planned to discard. Whether a failed call is billed depends on the active provider and route rules; the Google Standard output table does not answer that question.
Treat quality as a set of acceptance failures
Google describes Gemini 3.1 Flash Image as the speed-and-efficiency model for quick interaction and high throughput, while Gemini 3 Pro Image is positioned for professional asset production. That supports a default-and-escalation workflow. It does not create a universal “95% of Pro quality” score.
Hold the prompt, references, size, and acceptance criteria constant, then review five failure types:
- Text and numbers: spelling, prices, dates, units, line breaks, and visual hierarchy;
- Objects and spatial relationships: counts, left/right placement, occlusion, and multi-element instructions;
- Identity, product, and brand consistency: faces, packaging, logos, colors, and style across a set;
- Edit locality: whether changing one region disturbs previously approved areas;
- Delivered file: actual pixel dimensions, crop, readable detail, and fitness for the final channel.
Keep Nano Banana 2 when the work passes review
Social graphics, blog art, product concepts, ad variants, thumbnails, and conversational edits usually need a strong usable direction quickly. NB2 covers 0.5K through 4K and is designed for interactive and high-volume work. If the output passes your acceptance checklist, rerunning it with Pro because of the label adds cost without solving a reader or product problem.
Pay for Pro when the failure is valuable enough to fix
Pro has the clearest role in long in-image copy, menus and price cards, structured infographics, complex product mockups, campaign key art, and other assets under formal review. Google’s Apps workflow specifically calls out extra detail for text rendering and infographics when using Redo with Pro.
Pro is still not a no-review model. Text, facts, small details, identities, and layouts can remain wrong. “Professional asset production” describes its intended lane; it is not an accuracy guarantee.
Measure your queue, not someone else’s stopwatch
Nano Banana 2 is officially optimized for speed and high-volume use cases, making it the sensible first route for interactive tools and bulk work. Google does not publish one end-to-end latency SLA that applies across regions, accounts, output sizes, input complexity, and load.
Third-party claims such as “4–6 seconds versus 10–20 seconds” may describe a real test, but not your production contract. Latency changes with:
- 0.5K, 1K, 2K, or 4K output;
- reference count, video input, and edit complexity;
- thinking and Web/Image Search grounding;
- concurrency, rate limits, retries, region, and queue conditions;
- whether the returned image passes review on the first attempt.
Run both models through the same client with the same prompt class, references, output size, and acceptance criteria. Collect P50 and P95 latency, 429/retry rate, and acceptance rate. For the user experience, queue + generation + retries + review is the relevant time. A quick response that needs three reruns can lose both the speed and cost comparison.
Route the same job through a two-stage workflow
Pro is a conditional escalation route for valuable failures, not the automatic destination of every image request.
Stage 1: explore and produce volume on Nano Banana 2
Use NB2 to establish direction, composition, color, copy placement, and variants. Discarding images is expected here: the job is to narrow options quickly, not to make every call a final asset. Social variants, blog visuals, e-commerce concepts, thumbnails, and early localization frequently finish in this stage.
Stage 2: escalate a near-final candidate for a named reason
Once a candidate is close, check text, spatial relations, identity/brand, edit locality, and delivered pixels. If an important asset still fails, keep the prompt, references, size, and acceptance criteria stable and try Pro. That comparison tells you whether Pro improved acceptance; changing the model and the brief at the same time does not.
In Gemini Apps, eligible subscribers can use Redo with Pro. In an API product, encode the business rule explicitly—for example, ordinary jobs start on gemini-3.1-flash-image, while a high-value asset with a text/layout acceptance failure can move to gemini-3-pro-image. Do not copy a fixed retry count from another workload; set the threshold from your failure cost and live route billing.
Validate the route you will actually use
To compare outputs before integration, you can run the same prompt, references, and acceptance criteria in YingTu’s browser comparison. Its displayed route prices are current estimates for that service, not Google’s official price table; credits, access, concurrency, and failure billing depend on the live account and route.
Developers who need an API gateway can inspect LaoZhang API’s current image-model documentation, then verify the live model list, price, and account rules before calling it. Use the official Gemini Developer API when you need Google’s provider-native capabilities, billing, and contract. For adjacent questions, calculate Nano Banana 2 by output size or decide whether Pro is still worth using after NB2.
The durable decision rule is simple: Nano Banana 2 is the default production lane; Nano Banana Pro is the professional escalation triggered by an observable failure. Price the resolution, measure accepted outputs, and let review data—not a “faster” or “better” headline—decide where Pro pays for itself.