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Claude Opus 4.6 vs GPT-5.3 Codex

A detailed comparison of Claude Opus 4.6 (Anthropic) and GPT-5.3 Codex (OpenAI) across pricing, performance, and features.

Pricing Comparison

MetricClaude Opus 4.6GPT-5.3 CodexDifference
Input / 1M tokens$5.00$2.00-60%
Output / 1M tokens$25.00$16.00-36%
Context window200K200K
Max output32K65.536K

Benchmark Comparison

BenchmarkClaude Opus 4.6GPT-5.3 Codex
MMLU-Pro89.5%90%
HumanEval95%96.5%
GPQA75.5%78%

Capabilities

CapabilityClaude Opus 4.6GPT-5.3 Codex
code
reasoning
text
tool-use
vision

Claude Opus 4.6 Strengths

  • Best-in-class agentic tool use and coding
  • 1M context available in beta (Tier 4)
  • Strong at following complex multi-step instructions

Claude Opus 4.6 Weaknesses

  • Premium pricing ($10/$37.50 at 1M context)
  • 1M context beta is Tier 4 only

GPT-5.3 Codex Strengths

  • Best coding model from OpenAI
  • Large output window (65K tokens)
  • Strong reasoning for complex tasks

GPT-5.3 Codex Weaknesses

  • API access not yet available
  • Premium pricing

Quick Verdict

Best value: GPT-5.3 Codex is the more affordable option at $2/$16 per 1M tokens.

Higher benchmarks: GPT-5.3 Codex scores higher on average across available benchmarks (88.2% avg).

Choose GPT-5.3 Codex if cost matters most. Choose Claude Opus 4.6 if you need the best possible quality for complex tasks.

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