Gemini 3.5 Flash vs Gemini 3.5 Pro
Gemini 3.5 Pro and Gemini 3.5 Flash answer different Gemini 3.5 deployment questions. Flash is already available and priced for high-volume multimodal work. Pro is the preview flagship with a larger 2M-token context window, but public pricing and full API details are still pending.
Use Gemini 3.5 Flash when you need a callable, priced Gemini route now. Wait for Gemini 3.5 Pro when the app needs the larger 2M-token context window or flagship reasoning quality, but do not commit to the upgrade until Google confirms GA access, token pricing, rate limits, and benchmark evidence.
Decision scorecard
Local evidence first| Signal | Gemini 3.5 Flash | Gemini 3.5 Pro |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | reasoning-heavy apps, multimodal apps, and long-context analysis |
| Decision fit | Coding, RAG, and Agents | Long context and Vision |
| Context window | 1.05m | 2m |
| Cheapest output | $9/1M tokens | - |
| Provider routes | 4 tracked | 0 tracked |
| Shared benchmarks | 0 shared | 0 shared |
Decision tradeoffs
- Gemini 3.5 Flash has broader tracked provider coverage for fallback and procurement flexibility.
- Gemini 3.5 Flash uniquely exposes Function calling, Tool use, and Structured outputs in local model data.
- Local decision data tags Gemini 3.5 Flash for Coding, RAG, and Agents.
- Gemini 3.5 Pro has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Local decision data tags Gemini 3.5 Pro for Long context and Vision.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Gemini 3.5 Flash
$3,450
Cheapest tracked route/tier: Google AI Studio
Gemini 3.5 Pro
Unavailable
No complete token price in local provider data
Cost delta unavailable until both models have sourced input and output token prices.
Switch friction
- No overlapping tracked provider route is sourced for Gemini 3.5 Flash and Gemini 3.5 Pro; plan for SDK, billing, or endpoint changes.
- Check replacement coverage for Function calling, Tool use, and Structured outputs before moving production traffic.
- No overlapping tracked provider route is sourced for Gemini 3.5 Pro and Gemini 3.5 Flash; plan for SDK, billing, or endpoint changes.
- Gemini 3.5 Flash adds Function calling, Tool use, and Structured outputs in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-05-19 | 2026-05-19 |
| Context window | 1.05m | 2m |
| Parameters | — | — |
| Architecture | Decoder Only | - |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | 2025-01 | - |
Pricing and availability
| Pricing attribute | Gemini 3.5 Flash | Gemini 3.5 Pro |
|---|---|---|
| Input price | $1.50/1M tokens | - |
| Output price | $9/1M tokens | - |
| Providers | - |
Capabilities
| Capability | Gemini 3.5 Flash | Gemini 3.5 Pro |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| Function calling | Yes | No |
| Tool use | Yes | No |
| Structured outputs | Yes | No |
| Code execution | Yes | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark scores are currently available for this pair.
Deep dive
The main hard spec is context. Gemini 3.5 Pro is tracked at 2M tokens, while Gemini 3.5 Flash is tracked just above 1M tokens. That difference matters only when your requests actually exceed Flash's window or need the higher-end Pro reasoning profile.
Flash is the production default today because it has provider rows, pricing, and benchmark evidence in the local data. Pro remains a preview entry, so unknown pricing and route coverage are the gating risks.
Do not frame Pro as simply a more expensive Flash until Google confirms official rates. The DAT-6286 handoff explicitly says not to use speculative Pro pricing, so cost comparisons should remain blank or qualitative until GA.
The upgrade test is straightforward: keep Flash for high-volume Gemini traffic, then retest Pro on the subset of tasks where long context, multimodal depth, or harder reasoning currently cause measurable failures.
FAQ
Which has a larger context window, Gemini 3.5 Flash or Gemini 3.5 Pro?
Gemini 3.5 Pro supports 2m tokens, while Gemini 3.5 Flash supports 1.05m tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Is Gemini 3.5 Flash or Gemini 3.5 Pro open source?
Gemini 3.5 Flash is listed under Proprietary. Gemini 3.5 Pro is listed under Proprietary. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Gemini 3.5 Flash or Gemini 3.5 Pro?
Both Gemini 3.5 Flash and Gemini 3.5 Pro expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for multimodal input, Gemini 3.5 Flash or Gemini 3.5 Pro?
Both Gemini 3.5 Flash and Gemini 3.5 Pro expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Which is better for reasoning mode, Gemini 3.5 Flash or Gemini 3.5 Pro?
Both Gemini 3.5 Flash and Gemini 3.5 Pro expose reasoning mode. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Gemini 3.5 Flash and Gemini 3.5 Pro?
Gemini 3.5 Flash is available on Google AI Studio, GCP Vertex AI, Vercel AI Gateway, and OpenRouter. Gemini 3.5 Pro is available on the tracked providers still being sourced. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-06-20. Data sourced from public model cards and provider documentation.