Gemini 2.5 Pro vs Gemini 3.5 Flash
Choose Gemini 2.5 Pro when lower standard input cost matters more; choose Gemini 3.5 Flash when lower output cost is the better fit. Both expose about 1M tokens of context. No general Coding winner is shown because Google's published results use different SWE-bench variants, model releases, and agent configurations.
Choose Gemini 2.5 Pro when its lower standard input price or established Pro behavior fits the workload; choose Gemini 3.5 Flash when its lower output price, newer Flash surface, or latency profile is the better fit. Treat coding performance as an evaluation gap until both exact variants are published on the same benchmark version and compatible harness.
Decision scorecard
Local evidence first| Signal | Gemini 2.5 Pro | Gemini 3.5 Flash |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Coding, RAG, and Agents | Coding, RAG, and Agents |
| Context window | 1m | 1.05m |
| Cheapest output | $10/1M tokens | $9/1M tokens |
| Provider routes | 4 tracked | 4 tracked |
| Shared benchmarks | Withheld | Withheld |
Decision tradeoffs
- Local decision data tags Gemini 2.5 Pro for Coding, RAG, and Agents.
- Gemini 3.5 Flash has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Gemini 3.5 Flash has the lower cheapest tracked output price at $9/1M tokens.
- Local decision data tags Gemini 3.5 Flash for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Gemini 2.5 Pro
$3,500
Cheapest tracked route/tier: Google AI Studio <=200K tokens
Gemini 3.5 Flash
$3,450
Cheapest tracked route/tier: Google AI Studio
Estimated monthly gap: $50.00. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on Google AI Studio, GCP Vertex AI, and Vercel AI Gateway; start route-level A/B tests there.
- Gemini 3.5 Flash is $1/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Provider overlap exists on Google AI Studio, GCP Vertex AI, and OpenRouter; start route-level A/B tests there.
- Gemini 2.5 Pro is $1/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-06-17 | 2026-05-19 |
| Context window | 1m | 1.05m |
| Parameters | — | — |
| Architecture | Decoder Only | Decoder Only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Weights | Not released | Not released |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | 2025-01 | 2025-01 |
Pricing and availability
| Pricing attribute | Gemini 2.5 Pro | Gemini 3.5 Flash |
|---|---|---|
| Input price |
| $1.50/1M tokens |
| Output price |
| $9/1M tokens |
| Providers |
Capabilities
| Capability | Gemini 2.5 Pro | Gemini 3.5 Flash |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| JSON / Tool use | Yes | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No like-for-like benchmark rows are shown for this pair.
Harness caveat. Google reports Gemini 2.5 Pro Experimental on SWE-bench Verified with a custom agent setup and Gemini 3.5 Flash on SWE-bench Pro Public with an internal Antigravity harness. Different benchmark variants and configurations do not support a coding winner.
Continue comparing
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Last reviewed: 2026-06-29. Data sourced from public model cards and provider documentation.