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OpenAI: o1 vs OpenAI: GPT-5.1-Codex

Head-to-head API cost, context, and performance comparison. Synced at 2:27:54 PM.

Executive Summary

When evaluating OpenAI: o1 against OpenAI: GPT-5.1-Codex, the pricing structure is a key differentiator. OpenAI: GPT-5.1-Codex is approximately 85% more cost-effective per 1 million tokens overall.

However, when looking at raw reasoning capabilities, OpenAI: GPT-5.1-Codex leads with a statistical ELO score of 1481. For tasks involving complex logic, coding, or instruction-following, developers might prefer OpenAI: GPT-5.1-Codex, provided their budget allows for the API burn rate.

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Raw Technical comparison

Metric
OpenAI: o1
OpenAI: GPT-5.1-Codex
Performance (ELO)
1481
1481
Input Cost / 1M
$15.00
$1.25
Output Cost / 1M
$60.00
$10.00
Context Window
200,000 tokens
400,000 tokens

Verdict

If you are looking for pure performance and capability, Tie is statistically superior. However, if API burn rate is the primary concern, OpenAI: GPT-5.1-Codex wins out aggressively in pricing.

People Also Ask

Is OpenAI: o1 cheaper than OpenAI: GPT-5.1-Codex?

No. OpenAI: GPT-5.1-Codex is the more cost-effective model, operating at a lower price point per 1 million tokens.

Which model has the larger context window?

The OpenAI: GPT-5.1-Codex model has the advantage in memory, offering a massive 400,000 token limit for document ingestion.

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