o1 Pro Review: OpenAI's Reasoning Model for Hard Problems

Review of o1 Pro

★ 4.7/5 · Updated 2026-06-17

|

What is o1 Pro?

o1 Pro is OpenAI's flagship reasoning model, released in late 2025. It uses chain-of-thought reasoning with extended 'thinking time' to solve hard problems in math, science, and code. Available via ChatGPT Pro ($200/month) and the OpenAI API (custom pricing).

How it works

o1 Pro spends 30 seconds to 5 minutes 'thinking' before producing an answer. The thinking is hidden from the user, but it allows the model to try multiple approaches, catch errors, and refine its reasoning. For hard problems, this is the difference between a wrong answer and a right one.

o1 Pro vs GPT-5

GPT-5 is fast (returns in 2-5 seconds) and good for most tasks. o1 Pro is slow (30 seconds to 5 minutes) but better at hard reasoning. For 'what is the capital of France', use GPT-5. For 'solve this olympiad problem', use o1 Pro.

o1 Pro vs Claude 4 Opus

Claude 4 Opus is also a reasoning model, but with different strengths. o1 Pro is better at math and science (higher scores on AIME, GPQA). Claude 4 Opus is better at coding and writing. For STEM problems, o1 Pro wins. For coding, Claude wins.

Benchmarks

o1 Pro scores 96% on AIME 2025 (math olympiad), 92% on GPQA Diamond (graduate-level science), and 78% on SWE-bench Verified (real GitHub issues). GPT-5 scores 88% on AIME, 86% on GPQA, 76% on SWE-bench. Claude 4 Opus scores 84% on AIME, 89% on GPQA, 78% on SWE-bench.

Use cases

Math problem solving. Scientific research. Hard debugging (e.g., 'why is this distributed system race-conditioning?'). Strategic planning. Complex code refactors. Anything that requires deep reasoning over multiple steps.

Speed

o1 Pro is slow. Simple queries take 30-60 seconds. Hard queries take 2-5 minutes. You can't use o1 Pro for real-time applications. For background tasks where quality matters more than speed, o1 Pro is the right pick.

Cost

API pricing is $150/M input, $600/M output. A typical query costs $0.50-$2. ChatGPT Pro ($200/month) includes unlimited o1 Pro usage. For API access, o1 Pro is the most expensive model OpenAI offers. For ChatGPT Pro users, it's included.

Reliability

o1 Pro is more reliable than GPT-5 for hard problems. It checks its own work and catches errors. For tasks where you can't afford a wrong answer (medical research, financial modeling, safety-critical code), o1 Pro is the safer choice.

Limitations

o1 Pro is bad at creative writing, conversational chat, and tasks that don't require reasoning. It overthinks simple problems. Use GPT-5 for chat, o1 Pro for hard reasoning. Also, o1 Pro doesn't have vision or audio input (yet).

Who should use o1 Pro?

Researchers, scientists, mathematicians, and engineers working on hard problems. Anyone who needs reliable answers for high-stakes questions. People who can afford the time (and API cost) of slow reasoning.

Who should not use o1 Pro?

Anyone who needs fast responses (use GPT-5 or Claude). Creative writing tasks (use Claude). Coding tasks where Claude 4 Opus is comparable (use Claude). Anyone on a budget (o1 Pro is expensive).

Bottom line

o1 Pro is the best reasoning model in 2026. It wins on math, science, and hard problem-solving. It's slow and expensive, but for the right use cases, the quality is unmatched. If you need an answer you can trust, o1 Pro is the right pick.

|

Visit o1 Pro →

← Back to all reviews

Related on saas.pet