# o1

o1 is an AI model released by OpenAI on Dec 5 2024. It has a 200k context window. At release it scored 75.7% on GPQA Diamond.

## Facts

| Field | Value |
| --- | --- |
| Model | o1 |
| Developer | OpenAI |
| Release date | Thursday, Dec 5 2024 |
| Licensing | Proprietary |
| Context window | 200k |

## API pricing

All rates in USD per 1,000,000 tokens, pay-as-you-go.

| Tier | Input | Cached input | Output |
| --- | --- | --- | --- |
| All documented contexts | $15.00 | $7.50 | $60.00 |

Verified August 18, 2026 against the first-party source: https://developers.openai.com/api/docs/models/o1

## Benchmark scores published at release

| Benchmark | Score | Source | What it measures |
| --- | --- | --- | --- |
| GPQA Diamond | 75.7% | Lab | Graduate-level science questions in biology, physics, and chemistry — hard enough that subject-matter PhDs score around 65%. Higher is better. |

## About o1

o1, released December 5, 2024 after a September preview, was the first production reasoning model: instead of answering immediately, it generates a long private chain of thought trained with reinforcement learning before responding. The approach produced dramatic gains on competition mathematics, science, and hard coding problems that had resisted ordinary scaling.

o1 established the test-time-compute paradigm that reshaped the entire industry — within months every major lab shipped a reasoning model, from DeepSeek R1 to Gemini 2.5 Pro to Claude 3.7 Sonnet's extended thinking. Its own line moved fast too: o3-mini arrived in January 2025 and the full o3 in April 2025.

## Questions and answers

### When was o1 released?

o1 was released by OpenAI on Thursday, Dec 5 2024.

### Who made o1?

o1 was built by OpenAI. Creators of ChatGPT and the GPT series of models. Pioneered large-scale language model research.

### How much does o1 cost?

o1 costs $15.00 per million input tokens and $60.00 per million output tokens through the OpenAI API. Cached input is $7.50 per million tokens. Rates are pay-as-you-go API prices verified against OpenAI's published pricing on August 18, 2026.

### What benchmark scores did o1 get?

o1 reports 1 tracked benchmark score — GPQA Diamond: 75.7%. Scores are the figures published at release by OpenAI.

### What is the context window of o1?

o1 has a context window of 200k. That is the maximum amount of input plus output the model can hold in a single request.

### Is o1 open source?

No. o1 is a proprietary model. The weights are not published — it is available only through the provider's own API, apps, or partner platforms.

### What came before and after o1?

OpenAI's previous tracked release was o1-mini on Sep 12 2024, 84 days earlier. It was followed by o3-mini on Jan 31 2025.


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Canonical page: https://aireleasetracker.com/model/openai/o1
Full dataset: https://aireleasetracker.com/llms-full.txt · JSON: https://aireleasetracker.com/models.json
Source: AI Release Tracker (https://aireleasetracker.com). Benchmark scores are the figures published by the releasing lab at launch.