Model Comparison
o1 vs Gemini 2.5 FlashWhich is better in 2026?
Gemini 2.5 Flash significantly outperforms across most benchmarks. Gemini 2.5 Flash is 30.9x cheaper per token.
Verdict: o1 vs Gemini 2.5 Flash — which is better?
o1 (by OpenAI) and Gemini 2.5 Flash (by Google) are two of the AI models people compare most. Here is how they stack up on benchmarks, price and capabilities, and which one to pick in 2026.
o1 outperforms in 1 benchmarks (SimpleQA), while Gemini 2.5 Flash is better at 4 benchmarks (AIME 2024, GPQA, MMMU, SWE-Bench Verified). Gemini 2.5 Flash significantly outperforms across most benchmarks.
On price, Gemini 2.5 Flash is roughly 30.9x cheaper per token on a blended 3:1 input/output basis, which adds up quickly at production volume.
Gemini 2.5 Flash also accepts a larger context window (1,048,576 input tokens), making it the stronger choice for long documents and large codebases.
Choose o1 if…
- you want predictable pricing at $15.00/M input and $60.00/M output
Choose Gemini 2.5 Flash if…
- you want the strongest raw capability — it leads on 4 of 5 shared benchmarks
- cost matters — it's about 30.9x cheaper per token
- you process long inputs — it offers a 1,048,576 token context window
- you want the most recent training data — it shipped May 2025
Performance Benchmarks
Comparative analysis across standard metrics
o1 outperforms in 1 benchmarks (SimpleQA), while Gemini 2.5 Flash is better at 4 benchmarks (AIME 2024, GPQA, MMMU, SWE-Bench Verified).
Gemini 2.5 Flash significantly outperforms across most benchmarks.
Arena Performance
Human preference votes
Pricing Analysis
Price comparison per million tokens
For input processing, o1 ($15.00/1M tokens) is 50.0x more expensive than Gemini 2.5 Flash ($0.30/1M tokens).
For output processing, o1 ($60.00/1M tokens) is 24.0x more expensive than Gemini 2.5 Flash ($2.50/1M tokens).
In conclusion, o1 is more expensive than Gemini 2.5 Flash.*
* Using a 3:1 ratio of input to output tokens
Context Window
Maximum input and output token capacity
Gemini 2.5 Flash accepts 1,048,576 input tokens compared to o1's 200,000 tokens. o1 can generate longer responses up to 100,000 tokens, while Gemini 2.5 Flash is limited to 65,536 tokens.
Input Capabilities
Supported data types and modalities
Gemini 2.5 Flash supports multimodal inputs, whereas o1 does not.
Gemini 2.5 Flash can handle both text and other forms of data like images, making it suitable for multimodal applications.
o1
Gemini 2.5 Flash
License
Usage and distribution terms
Both models are licensed under proprietary licenses.
Both models have usage restrictions defined by their respective organizations.
Proprietary
Closed source
Proprietary
Closed source
Release Timeline
When each model was launched
o1 was released on 2024-12-17, while Gemini 2.5 Flash was released on 2025-05-20.
Gemini 2.5 Flash is 5 months newer than o1.
Dec 17, 2024
1.5 years ago
May 20, 2025
1.1 years ago
5mo newerKnowledge Cutoff
When training data ends
Gemini 2.5 Flash has a documented knowledge cutoff of 2025-01-31, while o1's cutoff date is not specified.
We can confirm Gemini 2.5 Flash's training data extends to 2025-01-31, but cannot make a direct comparison without o1's cutoff date.
—
Jan 2025
Provider Availability
o1 is available from Azure, OpenAI. Gemini 2.5 Flash is available from Google.
o1
Gemini 2.5 Flash
Outputs Comparison
Key Takeaways
o1
View detailsOpenAI
o1Gemini 2.5 FlashDetailed Comparison
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FAQ
Common questions about o1 vs Gemini 2.5 Flash.