o4 for reasoning
o4 is ranked #6 on LLMDex's llm for reasoning ranking out of 6 models we track for this use case. Below, the specific reasons it slots where it does, and when you should reach for an alternative.
Updated
At a glance
- Rank
- #6 of 6
- Context
- 200K tokens
- Output / 1M
- Pricing not published
- Released
- Dec 2025
Why o4 fits this task
Three things about o4 that map directly onto what this task rewards: Exceptional performance on hard math and reasoning benchmarks; Strong scientific reasoning. Beyond the task-specific fit, o4 also brings good at multi-step planning and verification, both of which compound when the workload broadens.
The criteria this task rewards
LLMDex ranks best llm for reasoning on 5 criteria , these are the axes the ranking uses, in priority order:
- GPQA Diamond performance
- ARC-AGI public set scores
- Chain-of-thought coherence on novel puzzles
- Reasoning-token cost, expensive on flagship reasoning models
- Latency budget, reasoning runs are slow by design
How o4 scores on each axis
Where o4 costs you: slow, reasoning tokens take real wall-clock time. For most teams this is acceptable on this workload, the value of the strengths above outweighs the cost. For cost-bound workloads or teams with strict latency budgets, run an eval against the next two ranked models on real data before committing.
Strengths that pay off here
- Exceptional performance on hard math and reasoning benchmarks
- Good at multi-step planning and verification
- Strong scientific reasoning
Tracked weaknesses
- Slow, reasoning tokens take real wall-clock time
- Expensive on reasoning-heavy queries
- Overkill for chat or simple tasks
When to pick something else
If you can pay slightly more or accept slightly different tradeoffs, Gemini 3 Pro from Google ranks one position higher and tends to win on the hardest cases. Google's late-2025 flagship, set new benchmarks on long-context, vision, and reasoning at competitive pricing.
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Other models for reasoning
- o3 for reasoning
OpenAI's flagship reasoning model, set the bar for hard math, GPQA, and agent benchmarks in 2025.
Read guide - GPT-5.5 for reasoning
OpenAI's mid-cycle GPT-5 refresh, improved reasoning, tool use, and multimodal grounding over the 2025 launch.
Read guide - Claude Opus 4.7 for reasoning
Anthropic's mid-2026 flagship, ahead on SWE-bench, agent reliability, and writing quality.
Read guide - DeepSeek-R1 for reasoning
First open-weight reasoning model to match o1, the release that proved RL-from-scratch reasoning training was reproducible.
Read guide - Gemini 3 Pro for reasoning
Google's late-2025 flagship, set new benchmarks on long-context, vision, and reasoning at competitive pricing.
Read guide
o4 for other use cases
Direct comparisons
Frequently asked
Is o4 good for reasoning?
o4 is ranked #6 on LLMDex's reasoning list. OpenAI's late-2025 standalone reasoning model, an evolution of o3 with deeper chain-of-thought and stronger multimodal reasoning.How much does o4 cost for reasoning?
OpenAI has not published per-token pricing for o4 at the time of writing.What's a cheaper alternative to o4 for reasoning?
Look at the full Best LLM for Reasoning ranking for cheaper picks at lower ranks.When should I NOT use o4 for reasoning?
Tracked weakness: Slow, reasoning tokens take real wall-clock time. If that constraint is binding for your workload, the next-ranked model on this task is the safer pick.
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