GPT-5 nano vs o3-pro
Detailed pricing comparison and cost analysis.
Updated September 2026
Cost Simulator
| Feature | GPT-5 nano | o3-pro |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Input Price (1M) | $0.05 | $20.00 |
| Output Price (1M) | $0.40 | $80.00 |
| Context Window | 400,000 | 200,000 |
Verdict
GPT-5 nano costs $0.05 per 1M input tokens and $0.40 per 1M output tokens. o3-pro costs $20.00 per 1M input tokens and $80.00 per 1M output tokens. GPT-5 nano is 100% cheaper on input tokens than o3-pro. For output tokens, GPT-5 nano is the more affordable option at $0.40/1M vs $80.00.
On context window, GPT-5 nano supports 400,000 tokens — meaning it can fit more conversation history, documents, or code in a single request. This matters for RAG pipelines, long document analysis, and agentic workflows where context builds up over many turns.
When to choose GPT-5 nano
- ✓ You need the lowest input token cost ($ 0.05/1M)
- ✓ Your workload is output-heavy — GPT-5 nano generates text cheaper
- ✓ You need a larger context window (400,000 tokens)
- ✓ You are already integrated with OpenAI
When to choose o3-pro
- ✓ 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 GPT-5 nano cheaper than o3-pro? ▼
GPT-5 nano is cheaper on input tokens at $0.05/1M vs $20.00/1M for o3-pro — a 100% saving.
What is the context window of GPT-5 nano vs o3-pro? ▼
GPT-5 nano has a 400,000-token context window. o3-pro has a 200,000-token context window. GPT-5 nano supports the larger context, suitable for longer documents and agentic workflows.
Which model is better: GPT-5 nano or o3-pro? ▼
The best choice depends on your use case. For cost efficiency on input tokens, GPT-5 nano is the cheaper option. For maximum context length, GPT-5 nano supports 400,000 tokens. Use the comparison table above to find the right fit for your workload.