O4 Mini
OpenAI's compact reasoning model with extended thinking, native vision input, and a 200K context window. Built for problems that need step-by-step logic — math, code, and structured analysis.
Model Specs
- Released
- Apr 2025
- Context window
- 200K tokens
- Capabilities
- reasoningextended-thinkingmultimodalfunction-calling
- Modalities
- textvision
About this model
O4 Mini is OpenAI's compact reasoning model, released on April 16, 2025 alongside o3. It's part of OpenAI's o-series — models that use extended thinking (chain-of-thought spent at inference time) to solve hard problems that non-reasoning models often miss. Where GPT-5 Mini optimizes for everyday speed and broad utility, O4 Mini optimizes for harder reasoning at a smaller-than-flagship size.
The model has a 200K-token context window — smaller than the GPT-5 family's 400K but still large enough for full codebases, lengthy documents, and complex multi-document synthesis. It accepts text and image input, produces text output, and ranks well on math benchmarks (AIME), competitive programming (HumanEval-class), and graduate-level science questions (GPQA).
On Renas AI, O4 Mini costs 0.06 credits per word — close to the flagship tier. The pricing reflects the compute cost of extended thinking. Reach for O4 Mini when you have a hard problem and want a structured, traceable reasoning trace; reach for GPT-5 Mini for the same problem at lower cost when you don't need explicit step-by-step output.
Key Strengths
Extended thinking for hard problems
O4 Mini spends extra inference time on chain-of-thought reasoning before producing the final answer. On math olympiad problems, complex code, and multi-step logic, this reliably improves accuracy over non-reasoning models.
200K context with native vision
Large enough for entire books, codebases, or document archives. Vision input is included at no extra credit — useful for analyzing diagrams, charts, or screenshots alongside text.
Strong on math and code
OpenAI positions o-series models as their best for technical reasoning. AIME math competitions, competitive coding, and scientific Q&A are the model's natural sweet spot.
Audit-friendly reasoning trace
When the model thinks step by step, you can read the reasoning and catch errors. This makes O4 Mini useful in domains where you need to verify how the model reached its answer (research, legal analysis, scientific work).
Function calling and structured output
Production-grade JSON mode and tool use, same as the rest of the GPT family. Suitable for agents that need to reason then act.
Available across Renas AI
Use O4 Mini in Chat, the AI Editor, and content generation flows. Same credit balance, no separate setup.
How it compares
O4 Mini sits between the budget GPT-5 Mini and the flagship GPT-5.2. Each makes a different trade-off between cost, reasoning depth, and knowledge recency.
| vs. Model | Verdict | Outcome |
|---|---|---|
| GPT-5.2 | GPT-5.2 is OpenAI's current flagship — newer (Dec 2025 vs April 2025), stronger benchmark scores (GPQA Diamond 93.2, AIME 100), and a 400K context vs O4 Mini's 200K. GPT-5.2 also costs slightly more (0.07 vs 0.06 credits per word) but is the better default for almost any reasoning task today. Pick O4 Mini only if you specifically prefer the o-series reasoning trace style. | Other wins |
| GPT-5 Mini | GPT-5 Mini is 6x cheaper (0.01 vs 0.06 credits per word) and has a larger 400K context. For everyday tasks the quality gap is small. Use O4 Mini when you specifically need the explicit reasoning trace, or when math/code-heavy problems are the bulk of your workload. | Depends |
| Claude Sonnet 4.5 | Claude Sonnet 4.5 is Renas's chat default and matches O4 Mini on price (0.07 vs 0.06 credits per word). Anthropic models are often preferred for long-form writing voice and software-engineering benchmarks (SWE-bench). O4 Mini is preferred for math olympiad and scientific reasoning. Test both on your specific workload. | Depends |
Pros
- Extended thinking improves accuracy on hard reasoning problems
- Audit-friendly reasoning trace — you can verify how the model arrived at the answer
- 200K context with native vision input
- Strong on math (AIME), code, and graduate-level science (GPQA)
- Production-grade function calling and JSON mode
Things to consider
- Smaller context window than GPT-5 family (200K vs 400K)
- Older release date (April 2025) — newer GPT-5 family generally outperforms it
- Knowledge cutoff not publicly disclosed by OpenAI
- Extended thinking adds latency — overkill for simple writing tasks
- AA Intelligence Index 33 vs 41 (GPT-5 Mini) and 51 (GPT-5.2) — newer OpenAI models score higher
Best use cases
Math and quantitative reasoning
Olympiad problems, statistical analysis, financial modeling, scientific calculations. Extended thinking shines on problems where the answer depends on multiple correct intermediate steps.
Code generation and debugging
Hard bug fixes that require reasoning about state, complex algorithm implementation, and architectural decisions. Pair with the full-codebase paste pattern in the AI Editor.
Scientific and academic research
Reading papers, generating literature summaries, designing experiments, analyzing data sets. The reasoning trace helps you spot misinterpretations before they propagate.
Strategic and analytical decisions
Multi-variable trade-off analyses, scenario planning, decision frameworks. The model's explicit reasoning makes it easier to verify the logic chain.
Multimodal technical analysis
Reviewing UI screenshots for accessibility, interpreting scientific diagrams, extracting structured data from charts. Vision + reasoning together work well on technical content.
Tool-using agents
Agents that need to think before acting — query a database, reason about results, decide on next steps. Function calling stays consistent across long agentic sessions.
How to use it on Renas AI
- 1
Step 1
Pick the surface that fits the task
O4 Mini is available in Renas AI Chat for conversational reasoning, the AI Editor for inline document analysis, and the AI Text Generator for one-shot reasoning tasks. Pick the one that matches the workflow.
- 2
Step 2
Select O4 Mini from the model picker
Use the model selector in any text tool. Choose O4 Mini specifically when the task is hard reasoning — math, complex code, multi-step analysis. For everyday writing, GPT-5 Mini is cheaper and nearly as capable; for the hardest tasks, GPT-5.2 has better benchmark scores.
- 3
Step 3
Provide the full problem and constraints
Reasoning models work best with the entire problem stated upfront — known constraints, success criteria, edge cases. The 200K context handles full codebases, long papers, and complex problem sets in a single message.
- 4
Step 4
Read the reasoning trace, then decide
O4 Mini often shows its work. Skim the reasoning before accepting the final answer — it's a fast way to spot wrong assumptions or missed cases. For automated pipelines, you can suppress the trace via system prompt.
Pricing
Pricing on Renas AI
Pay-as-you-go credits, no API keys, no rate limits.
~166,667 words on a 10,000-credit Spark plan
Frequently asked questions
Other OpenAI models
Other text models on Renas AI
Use O4 Mini for hard reasoning tasks
Run O4 Mini with your Renas AI subscription credits — no API key, no setup, no per-seat fees.
Try O4 Mini