GPT-5.1 vs Gemini 2.5 Pro Experimental
Compare pricing, context windows, and strengths for GPT-5.1 by OpenAI and Gemini 2.5 Pro Experimental by Google - and see how to put either to work in Appaca.
GPT-5.1
Flagship model for coding, reasoning, and agentic tasks with adjustable reasoning depth and multimodal input/output.
View GPT-5.1Gemini 2.5 Pro Experimental
Google's most advanced thinking model, leading benchmarks in reasoning, science, math, and coding with a massive multimodal context window.
View Gemini 2.5 Pro ExperimentalGPT-5.1 vs Gemini 2.5 Pro Experimental at a glance
Specs and pricing side by side, from the Appaca AI models directory.
| Spec | GPT-5.1 | Gemini 2.5 Pro Experimental |
|---|---|---|
| Provider | OpenAI | |
| Model type | Text | Text |
| Context window | 400K tokens | 1.05M tokens |
| Input price | $1.25 / 1M tokens | $1.5 / 1M tokens |
| Output price | $10 / 1M tokens | $6 / 1M tokens |
| Status | Current | Current |
How GPT-5.1 and Gemini 2.5 Pro Experimental differ
What the numbers mean in practice when choosing between GPT-5.1 and Gemini 2.5 Pro Experimental.
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GPT-5.1 is 17% cheaper on input tokens ($1.25 vs $1.5 per million), which adds up quickly in document-heavy workloads.
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Gemini 2.5 Pro Experimental is 40% cheaper on output tokens ($6 vs $10 per million) - the bigger factor for tools that generate long documents.
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Gemini 2.5 Pro Experimental's 1.05M tokens context window is roughly 2.6x larger than GPT-5.1's 400K tokens, so it can work across bigger codebases, contracts, or archives in one pass.
Strengths side by side
Where each model shines, according to benchmarks and provider positioning.
GPT-5.1
1. Configurable Reasoning for Agentic Tasks
- Built to excel in autonomous or semi-autonomous coding workflows, with adjustable reasoning effort for planning, refactoring and debugging.
2. Fast Multi-Modal Input with Large Output
- Accepts both text and image inputs while producing text outputs.
- Offers up to 128 k output tokens, allowing long responses and code generation across multiple files.
3. Large Context & Knowledge Cut-Off
- 400 k token context window supports processing large codebases or documents.
- Knowledge cut-off of Sep 30 2024 ensures familiarity with recent tools and frameworks.
4. Reasoning Token Support
- Provides explicit support for reasoning tokens, enabling developers to fine-tune the balance between reasoning depth and speed.
Gemini 2.5 Pro Experimental
1. State-of-the-art reasoning performance
- #1 on LMArena human preference leaderboard.
- Excels at advanced reasoning benchmarks like GPQA and AIME 2025.
- Achieves 18.8% on Humanity's Last Exam (no tools), representing frontier human-level reasoning.
2. New “thinking model” architecture
- Built with explicit reasoning steps internally before responding.
- Handles complex, multi-stage logic with higher accuracy and fewer hallucinations.
3. Elite science and mathematics capabilities
- Leads in math and science tasks across industry benchmarks.
- High performance without costly inference tricks like majority voting.
4. Exceptional coding abilities
- Major leap over Gemini 2.0 in coding performance.
- 63.8% on SWE-Bench Verified with custom agent setup.
- Strong at code transformation, debugging, and building agentic apps.
- Capable of generating full applications (e.g., a playable video game) from a single-line prompt.
5. Massive multimodal context
- Ships with a 1,000,000 token window (2M coming soon).
- Handles entire documents, datasets, video sequences, audio files, and large codebases.
- Maintains strong performance even at extreme context lengths.
6. Native multimodality across all inputs
- Understands and reasons over text, images, audio, video, and code.
- Designed for real-world, multi-source problem-solving and agent workflows.
7. Consistent high-quality outputs
- Improved post-training results in more accurate, coherent, and stylistically strong responses.
- Higher reliability across complex workloads.
8. Early availability for developers
- Available today in Google AI Studio for experimentation.
- Coming soon to Vertex AI with higher rate limits and production-ready access.
Use GPT-5.1 or Gemini 2.5 Pro Experimental - or both
Appaca is the AI workspace for operators. Build internal tools and AI co-workers powered by GPT-5.1 or Gemini 2.5 Pro Experimental - connected to your real data and ready for your whole team. No code, no deployment.
Describe it, and it's built
Tell the Appaca agent the internal tool you need and it builds a working app powered by GPT-5.1 or Gemini 2.5 Pro Experimental. No code, no API keys, no deployment.
Switch models without rebuilding
Start on GPT-5.1, test the same tool on Gemini 2.5 Pro Experimental, and keep whichever performs better - the rest of your app stays exactly as it is.
Automated for the whole team
Schedule tools to run on autopilot - daily digests, weekly reports, real-time triggers - and share them with your whole team from one workspace.
Describe it, and it's built
Tell the Appaca agent what your team needs and it builds a working app powered by GPT-5.1 or Gemini 2.5 Pro Experimental - connected to the tools you already use.
Related comparisons
See how GPT-5.1 and Gemini 2.5 Pro Experimental stack up against other models in the directory.
FAQs
Gemini 2.5 Pro Experimental is generally cheaper: $1.5 input / $6 output per million tokens, versus $1.25 / $10 for GPT-5.1. Actual cost depends on how many tokens your workload reads and writes.
Gemini 2.5 Pro Experimental has the larger context window at 1.05M tokens, compared to 400K tokens for GPT-5.1. A larger window means the model can consider more text at once - useful for long contracts, codebases, or months of records.
It depends on the job. Compare the pricing, context window, and strengths above against your workload - and remember the choice isn't permanent. In Appaca you can build a tool on GPT-5.1, test the same tool on Gemini 2.5 Pro Experimental, and switch at any time without rebuilding anything.
Yes. Appaca is a no-code AI workspace: describe the internal tool your team needs and the Appaca agent builds it as a working app powered by GPT-5.1, Gemini 2.5 Pro Experimental, or any other model in the directory - with a built-in database, team access, and integrations. No API keys to wire up and nothing to deploy.
Build AI tools with GPT-5.1 or Gemini 2.5 Pro Experimental
Describe the tool your team needs and get a working app powered by the model you choose - with a built-in database, team access, and integrations. No code, no deployment.