How much does a RAG app cost on Claude Opus 5.5?
Running a "chat with your docs" app that stuffs retrieved chunks into every prompt on Claude Opus 5.5 costs about $3,355/month for 500 users × 8 messages/day: that's $6.71 per user and $27.96 per 1,000 requests.
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Assumptions
- 500 users × 8 messages/day (120,000 per month)
- System prompt 600 tokens, retrieved context 4,000 tokens, user input 100, output 500 tokens
- Prompt cache hit rate 50%
- Claude Opus 5.5 list price: $4/1M input, $20/1M output, $0.2/1M cached input; context window 1,000,000 tokens
How Claude Opus 5.5 compares for a RAG app
13 of 14 other popular models are cheaper for this workload. Cheapest isn't always best: check the quality index, and consider routing easy requests to a cheap model and only hard ones to a frontier model.
| Model | Quality | Monthly | Per user |
|---|---|---|---|
| GPT-5 Nano | 13 | $50.58 | $0.10 |
| DeepSeek V4 Flash 0423 | 24.4 | $59.62 | $0.12 |
| Gemini 2.5 Flash Lite | 10.4 | $76.56 | $0.15 |
| Claude Haiku 5.5 | 43.4 | $84.06 | $0.17 |
| Llama 4 Maverick | 9.3 | $140 | $0.28 |
| DeepSeek V4 Pro 0423 | 30.4 | $252 | $0.50 |
| Gemini 3.8 Flash | 40.9 | $658 | $1.32 |
| GPT-5.4 Mini | 24.1 | $669 | $1.34 |
| Grok 4.3 | 24.9 | $817 | $1.63 |
| Grok 4.7 | 46.4 | $1,434 | $2.87 |
| Gemini 4 Argon | 52.6 | $1,594 | $3.19 |
| GPT-6.1 Sol | 51.8 | $1,678 | $3.36 |
| Claude Sonnet 5.5 | 56 | $1,678 | $3.36 |
| Claude Opus 5.5 | 57.6 | $3,355 | $6.71 |
| GPT-5.5 | 38.4 | $4,458 | $8.92 |
More Claude Opus 5.5 cost guides
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Prices: OpenRouter list prices (USD per 1M tokens), updated 2026-10-15. Estimates only; a month is 30 days. See how the math works.