Comparison · Updated Sep 19, 2026
GPT-5 vs Gemini 2.5 Pro
GPT-5 leads on general reasoning and coding; Gemini 2.5 Pro wins on raw context size and tight integration with Google's stack.
At a glance
| Spec | GPT-5 | Gemini 2.5 Pro |
|---|---|---|
| Released | Aug 7, 2025 | Mar 25, 2025 |
| Context window | 400K tokens | 1M tokens |
| Licence | Closed / API | Closed / API |
| Inputs | text, image | text, image, audio, video |
| Public API | Yes | Yes |
Model A
GPT-5
OpenAI's next-generation flagship model succeeding GPT-4o.
Aug 7, 2025
Model B
Gemini 2.5 Pro
Reasoning-focused member of the Gemini 2.5 family.
Mar 25, 2025
Differences
| Attribute | GPT-5 | Gemini 2.5 Pro |
|---|---|---|
| Released | August 2025 | March 2025 |
| Context window | 400K tokens | 1M tokens |
| Inputs | Text, image | Text, image, audio, video |
| Licence | Closed, API | Closed, API |
| Best for | Reasoning, agentic coding | Huge context, Google stack |
Verdict
GPT-5 for hard reasoning and agentic coding. Gemini 2.5 Pro when you need a million tokens of context or Google Cloud integration.
Analysis
Reasoning
GPT-5 (August 2025) is the stronger general reasoner and the safer default for agentic coding, tool use and long task chains.
Context
Gemini 2.5 Pro''s 1M-token window lets you drop entire codebases, video transcripts or document sets into a single request without retrieval plumbing.
Ecosystem
Gemini is the natural choice inside Google Cloud, Workspace and Vertex AI. GPT-5 has the broader third-party tooling ecosystem.
Cost
Gemini 2.5 Pro is generally the cheaper option for very large inputs; GPT-5 is priced for reasoning quality.
Frequently asked
- Which has the bigger context window?
- Gemini 2.5 Pro, at roughly 1M tokens against GPT-5's 400K.
- Which is better for agents?
- GPT-5 is generally more reliable over long tool-using task chains.