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openai/o3-mini
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o3 Mini

OpenAI o3-mini is a cost-efficient language model optimized for STEM reasoning tasks, particularly excelling in science, mathematics, and coding. This model supports the `reasoning_effort` parameter, which can be set to "high", "medium", or "low" to control the thinking time of the model. The default is "medium". OpenRouter also offers the model slug `openai/o3-mini-high` to default the parameter to "high". The model features three adjustable reasoning effort levels and supports key developer capabilities including function calling, structured outputs, and streaming, though it does not include vision processing capabilities. The model demonstrates significant improvements over its predecessor, with expert testers preferring its responses 56% of the time and noting a 39% reduction in major errors on complex questions. With medium reasoning effort settings, o3-mini matches the performance of the larger o1 model on challenging reasoning evaluations like AIME and GPQA, while maintaining lower latency and cost.

1/31/2025
200,000 tokens
#176 Text (Japanese)

Specifications

Modalities

Input
text
file
Output
text

Supported Parameters

max_tokens
response_format
seed
structured_outputs
tool_choice
tools

Max Output Tokens

100,000

Data policy

Prompt retention
Unknown — we could not confirm
Training
Unknown — not declared

"Unknown" does not mean "safe". It means we could not confirm it.

Whether a provider trains on prompts is a declared value from our terms with them. Retention is determined from the upstream listing for every host this model can reach. Neither is guessed.

Frequently asked questions

Is o3 Mini available on FastMetal?
Not at the moment. GPT-6.1 Sol, from the same lab, is available on the FastMetal API today.
What is the context window of o3 Mini?
200,000 tokens, shared between the prompt and the response.
How does o3 Mini rank?
#176 on the public arena's Japanese board (ELO 1,297). Ranks move as the leaderboard is updated.

Leaderboard

Text
spanishELO: 1,339
#215
russianELO: 1,329
#231
CodingELO: 1,416
#198
MathELO: 1,382
#189
Creative WritingELO: 1,301
#241
Instruction FollowingELO: 1,343
#214
Hard PromptsELO: 1,371
#215
Multi-TurnELO: 1,339
#229
OverallELO: 1,348
#223
JapaneseELO: 1,297
#176
ChineseELO: 1,357
#235
KoreanELO: 1,291
#186
EnglishELO: 1,362
#228
frenchELO: 1,350
#211
germanELO: 1,324
#198

Rankings: LMArena leaderboard dataset (lmarena-ai/leaderboard-dataset), CC BY 4.0, snapshot 2026-10-22; category names mapped and ratings rounded by FastMetal.