Gemini 2.5 Pro vs GPT-5.5
Gemini 2.5 Pro (2025) and GPT-5.5 (2026) are frontier-tier reasoning models from Google DeepMind and OpenAI. Gemini 2.5 Pro ships a 1m-token context window, while GPT-5.5 ships a 1.05m-token context window. On MMLU PRO, GPT-5.5 leads by 1.9 pts. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
GPT-5.5 is safer overall; choose Gemini 2.5 Pro when coding workflow support matters.
Decision scorecard
Local evidence first| Signal | Gemini 2.5 Pro | GPT-5.5 |
|---|---|---|
| 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 | $30/1M tokens |
| Provider routes | 4 tracked | 3 tracked |
| Shared benchmarks | 9 rows | MMLU PRO leader |
Decision tradeoffs
- Gemini 2.5 Pro holds a shared-benchmark lead on AIME 2025, ahead by 5.5 points.
- Gemini 2.5 Pro has the lower cheapest tracked output price at $10/1M tokens.
- Gemini 2.5 Pro has broader tracked provider coverage for fallback and procurement flexibility.
- Local decision data tags Gemini 2.5 Pro for Coding, RAG, and Agents.
- GPT-5.5 holds a shared-benchmark lead on MMLU PRO, ahead by 1.9 points.
- GPT-5.5 has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Local decision data tags GPT-5.5 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
GPT-5.5
$11,500
Cheapest tracked route/tier: OpenAI API 0-272K input tokens
Estimated monthly gap: $8,000. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
- GPT-5.5 is $20/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Provider overlap exists on OpenRouter and Vercel AI Gateway; start route-level A/B tests there.
- Gemini 2.5 Pro is $20/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-06-17 | 2026-04-23 |
| Context window | 1m | 1.05m |
| Parameters | — | — |
| Architecture | decoder only | decoder only |
| License | Proprietary | Proprietary |
| Openness | Proprietary | Proprietary |
| Commercial use | Commercial use with conditions | Commercial use with conditions |
| Knowledge cutoff | 2025-01 | 2025-12 |
Pricing and availability
| Pricing attribute | Gemini 2.5 Pro | GPT-5.5 |
|---|---|---|
| Input price |
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| Output price |
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Capabilities
| Capability | Gemini 2.5 Pro | GPT-5.5 |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| Function calling | Yes | Yes |
| 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
| Benchmark | Gemini 2.5 Pro | GPT-5.5 |
|---|---|---|
| MMLU PRO | 86.2 | 88.1 |
| SWE-bench Verified | 63.8 | 82.6 |
| Google-Proof Q&A | 86.4 | 93.6 |
| AIME 2025 | 86.7 | 81.2 |
| Humanity's Last Exam | 18.8 | 41.4 |
| HumanEval | 93.1 | 94.2 |
| Chatbot Arena | 1398.0 | 1488.0 |
| Terminal-Bench 2.0 | 32.6 | 82.7 |
| Aider Polyglot | 83.1 | 88.0 |
Deep dive
On shared benchmark coverage, MMLU PRO has Gemini 2.5 Pro at 86.2 and GPT-5.5 at 88.1, with GPT-5.5 ahead by 1.9 points; SWE-bench Verified has Gemini 2.5 Pro at 63.8 and GPT-5.5 at 82.6, with GPT-5.5 ahead by 18.8 points; Google-Proof Q&A has Gemini 2.5 Pro at 86.4 and GPT-5.5 at 93.6, with GPT-5.5 ahead by 7.2 points. The largest visible gap is 18.8 points on SWE-bench Verified, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint is close: both models cover vision, multimodal input, reasoning mode, function calling, and tool use. That makes context budget, benchmark fit, and provider maturity more important than a simple checklist. If your application depends on one integration detail, verify it against the provider route you plan to use, not just the base model listing.
For cost, Gemini 2.5 Pro lists tiered pricing: <=200K tokens is $1.25/1M input and $10/1M output; >200K tokens is $2.50/1M input and $15/1M output, while GPT-5.5 lists tiered pricing: 0-272K input tokens is $5/1M input and $30/1M output; 272K+ input tokens is $8/1M input and $36/1M output. A 70/30 input-output blend puts Gemini 2.5 Pro lower by about $8.63 per million blended tokens. For tiered rows, this cheapest-track view can understate interactive or fast-lane spend, so compare the tier you will actually use. Availability is 4 providers versus 3, so concentration risk also matters.
Choose Gemini 2.5 Pro when coding workflow support, lower cheapest-tier input-token cost, and broader provider choice are central to the workload. Choose GPT-5.5 when coding workflow support and larger context windows are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Gemini 2.5 Pro or GPT-5.5?
GPT-5.5 supports 1.05m tokens, while Gemini 2.5 Pro supports 1m tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Gemini 2.5 Pro or GPT-5.5?
Gemini 2.5 Pro lists tiered pricing: <=200K tokens is $1.25/1M input and $10/1M output; >200K tokens is $2.50/1M input and $15/1M output. GPT-5.5 lists tiered pricing: 0-272K input tokens is $5/1M input and $30/1M output; 272K+ input tokens is $8/1M input and $36/1M output. Compare the tier you will actually use; cheap async pricing can overstate savings for interactive workflows. Provider discounts or batch pricing can still change the final bill.
Is Gemini 2.5 Pro or GPT-5.5 open source?
Gemini 2.5 Pro is listed under Proprietary. GPT-5.5 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 2.5 Pro or GPT-5.5?
Both Gemini 2.5 Pro and GPT-5.5 expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, Gemini 2.5 Pro or GPT-5.5?
Both Gemini 2.5 Pro and GPT-5.5 expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Where can I run Gemini 2.5 Pro and GPT-5.5?
Gemini 2.5 Pro is available on Google AI Studio, GCP Vertex AI, OpenRouter, and Vercel AI Gateway. GPT-5.5 is available on OpenAI API, OpenRouter, and Vercel AI Gateway. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-06-08. Data sourced from public model cards and provider documentation.