Claude Opus 5 vs o3
Detailed pricing comparison and cost analysis.
Updated September 2026
Cost Simulator
| Feature | Claude Opus 5 | o3 |
|---|---|---|
| Provider | Anthropic | OpenAI |
| Input Price (1M) | $5.00 | $2.00 |
| Output Price (1M) | $25.00 | $8.00 |
| Context Window | 1,000,000 | 200,000 |
Verdict
Claude Opus 5 costs $5.00 per 1M input tokens and $25.00 per 1M output tokens. o3 costs $2.00 per 1M input tokens and $8.00 per 1M output tokens. o3 is 60% cheaper on input tokens than Claude Opus 5. For output tokens, o3 is the more affordable option at $8.00/1M vs $25.00.
On context window, Claude Opus 5 supports 1,000,000 tokens — meaning it can fit more conversation history, documents, or code in a single request. This matters for RAG pipelines, long document analysis, and agentic workflows where context builds up over many turns.
When to choose Claude Opus 5
- ✓ You need a larger context window (1,000,000 tokens)
- ✓ You are already integrated with Anthropic
When to choose o3
- ✓ You need the lowest input token cost ($ 2.00/1M)
- ✓ Your workload is output-heavy — o3 generates text cheaper
- ✓ You are already integrated with OpenAI
Use the calculator above to simulate your specific workload and find the exact break-even point. For most applications, the cheapest model is the one that minimises your total monthly bill given your input-to-output token ratio.
Frequently Asked Questions
Is Claude Opus 5 cheaper than o3? ▼
o3 is cheaper on input tokens at $2.00/1M vs $5.00/1M for Claude Opus 5 — a 60% saving.
What is the context window of Claude Opus 5 vs o3? ▼
Claude Opus 5 has a 1,000,000-token context window. o3 has a 200,000-token context window. Claude Opus 5 supports the larger context, suitable for longer documents and agentic workflows.
Which model is better: Claude Opus 5 or o3? ▼
The best choice depends on your use case. For cost efficiency on input tokens, o3 is the cheaper option. For maximum context length, Claude Opus 5 supports 1,000,000 tokens. Use the comparison table above to find the right fit for your workload.