Model Details
o1-preview
Quick answer: o1-preview is OpenAI's September 2024 first public reasoning model, scoring 85.5% on MATH, 90.8% on MMLU, and 42.4% on SimpleQA. It introduced chain-of-thought reasoning to the OpenAI API — a preview release ahead of the full o1 model. It has been superseded by o1, o3, and o4-mini.
At a Glance
Where o1-preview leads
- First public o-series reasoning model — historically significant
- 90.8% MMLU — strong general knowledge (higher than o3-mini's 86.9%)
- 42.4% SimpleQA — better factual accuracy than later o-series models
- 85.5% MATH — strong mathematical reasoning for a 2024 model
- Good factual recall relative to other reasoning models
Where it lags
- Preview model — limited features vs full o1
- Superseded by o1, o3-mini, o3, and o4-mini in all dimensions
- October 2023 knowledge cutoff — over a year behind current models
- No vision support
- 128K context (vs 200K for o3-mini and o4-mini)
- Pricing no longer publicly listed
Best for: Historical comparisons; legacy integrations; understanding o-series model progression.
What o1-preview Is
o1-preview (released September 12, 2024) was OpenAI's first public deployment of the o-series reasoning paradigm — making chain-of-thought reasoning available through the API before the full o1 model launched in December 2024.
The model introduced a fundamentally different approach to generation: instead of producing output directly, o-series models "think" through problems using internal reasoning steps, then produce a final answer. This yielded dramatically improved performance on mathematics (85.5% MATH), science, and coding compared to GPT-4o.
o1-preview was explicitly a preview — limited context (128K vs 200K for o1), no image support, and fewer system prompt capabilities than the production o1. It was retired as the o-series portfolio expanded.
For historical context: o1-preview demonstrated that reasoning models would become the standard for complex tasks, setting the stage for the entire o-series roadmap.
Specifications
| Field | Value |
|---|---|
| Organization | OpenAI |
| Context window | 128,000 tokens |
| License | Proprietary (API only) |
| Release date | September 12, 2024 |
| Knowledge cutoff | October 2023 |
| Modality | Text only |
Pricing
o1-preview pricing is no longer publicly listed on the OpenAI pricing page — this model has been deprecated in favor of o1, o3-mini, and o4-mini.
Public Benchmark Scores
| Benchmark | Score | Source | Date |
|---|---|---|---|
| MATH | 85.5% | Benchgen evaluation | 2025-07 |
| MMLU | 90.8% | Benchgen evaluation | 2025-07 |
| SimpleQA | 42.4% | Benchgen evaluation | 2025-07 |
o1-preview vs Alternatives
| Model | MATH | MMLU | SimpleQA | Context |
|---|---|---|---|---|
| o1-preview | 85.5% | 90.8% | 42.4% | 128K |
| o3-mini | 97.9% | 86.9% | 15.0% | 200K |
| o1 | — | — | — | 200K |
| o4-mini | — | — | — | 200K |
o1-preview vs o3-mini: o3-mini is much stronger on MATH (97.9% vs 85.5%), but o1-preview has higher SimpleQA (42.4% vs 15.0%). o1-preview is a legacy model; use o3-mini or o4-mini for new work.
Related Models & Benchmarks
Frequently Asked Questions
What is o1-preview?
o1-preview is OpenAI's September 2024 first public reasoning model, scoring 85.5% MATH, 90.8% MMLU, and 42.4% SimpleQA. It was a preview release ahead of the full o1 model and has been superseded.Is o1-preview still available?
o1-preview has been deprecated and is no longer listed on the OpenAI pricing page. Migrate to o1, o3-mini, or o4-mini.What is the difference between o1-preview and o1?
o1-preview was a limited preview with 128K context and restricted features. The full o1 (December 2024) added 200K context, vision support, and more complete system prompt capabilities.Specs from OpenAI's o1-preview launch (September 2024) and Benchgen evaluations. Last updated 2026-07-24.
Benchmark Leaderboards
This model isn’t on any benchmark leaderboard yet.