API Pricing
AI API Pricing Guide 2026:
GPT-6 vs Claude 5.5 vs Gemini 3 vs Mistral
Current production AI API pricing, verified against official vendor sources. Compare GPT-6, Claude 5.5, Gemini 3 and Mistral side by side. Last verified: 2026-10-01.
16 min read·Updated October 2026
Current Production AI API Pricing (October 2026)
| Model | Provider | Input /1M | Output /1M | Context | Speed |
|---|---|---|---|---|---|
| GPT-6 Astra | OpenAI | $10.00 | $50.00 | 1.05M | Medium |
| GPT-6.1 Sol | OpenAI | $2.00 | $10.00 | 1.05M | Fast |
| GPT-6 Luna | OpenAI | $0.10 | $0.50 | 1.05M | Very Fast |
| Claude Fable 5.1 | Anthropic | $10.00 | $50.00 | 1M | Medium |
| Claude Opus 5.5 | Anthropic | $4.00 | $20.00 | 1M | Medium |
| Claude Sonnet 5.5 | Anthropic | $2.00 | $10.00 | 1M | Fast |
| Claude Haiku 4.5 | Anthropic | $1.00 | $5.00 | 200K | Very Fast |
| Gemini 3.1 Pro Preview* | $2.00 | $12.00 | 1M | Fast | |
| Gemini 3.8 Flash** | $0.75 | $3.75 | 1M | Very Fast | |
| Gemini 2.5 Flash-Lite | $0.10 | $0.40 | 1M | Very Fast | |
| Mistral Medium 3.5 | Mistral | $1.50 | $7.50 | 256K | Fast |
| Mistral Large 3 | Mistral | $0.50 | $1.50 | 256K | Fast |
| Mistral Small 4 | Mistral | $0.15 | $0.60 | 256K | Very Fast |
* Gemini 3.1 Pro Preview: $2/$12 for prompts up to 200K tokens, $4/$18 above. ** Gemini 3.8 Flash promotional rate through December 31, 2026; $1.50/$7.50 from January 1, 2027. GPT-6 prices apply up to 272K input tokens.
Real-World Cost Per Task (1,000 tasks)
Customer support reply
Gemini 2.5 Flash-Lite$0.13 ✓
GPT-6 Luna$0.15
Mistral Small 4$0.20
Claude Haiku 4.5$1.50
~500 input + 200 output tokens per reply — cost per 1,000 replies
Document summarization
Gemini 2.5 Flash-Lite$0.60 ✓
GPT-6 Luna$0.65
Gemini 3.8 Flash$4.88
Claude Sonnet 5.5$13.00
~4,000 input + 500 output tokens per doc — cost per 1,000 docs
Code generation
Gemini 2.5 Flash-Lite$0.42 ✓
GPT-6 Luna$0.50
Claude Haiku 4.5$5.00
Claude Sonnet 5.5$10.00
~1,000 input + 800 output tokens per task — cost per 1,000 tasks
Content moderation
Gemini 2.5 Flash-Lite$0.05 ✓
GPT-6 Luna$0.055
Mistral Small 4$0.075
Claude Haiku 4.5$0.55
~300 input + 50 output tokens per check — cost per 1,000 checks
Which AI Model Should You Choose?
Choose OpenAI GPT-6 if:
- GPT-6.1 Sol ($2/$10) is a strong default for coding and analysis, with very cheap cached input ($0.10/1M)
- GPT-6 Astra ($10/$50) is OpenAI's flagship for the hardest reasoning and research tasks
- GPT-6 Luna ($0.10/$0.50) covers high-volume simple work; all three have a 1.05M context window
Choose Claude Sonnet 5.5, Opus 5.5 or Fable 5.1 if:
- You need top-tier instruction-following and coding quality with a 1M-token context window
- Sonnet 5.5 is the production default at $2/1M input — half the price of Opus 5.5
- Opus 5.5 ($4/$20) and Fable 5.1 ($10/$50) are best reserved for the most demanding agentic or multi-step reasoning work
Choose Gemini Flash or Flash-Lite if:
- Cost efficiency is the top priority
- You need a 1M-token context for very long documents at a low price
- Gemini 2.5 Flash-Lite at $0.10/$0.40 is the cheapest capable model; Gemini 3.8 Flash ($0.75/$3.75 until 2027) is the stronger mid-price option
Choose Mistral or open-source if:
- Data privacy requires on-premise or EU-hosted deployment
- You want open-weights models with commercial-friendly licensing (Large 3 and Small 4 are Apache 2.0)
- Mistral Small 4 at $0.15/1M input is the cheapest current Mistral model; Mistral Medium 3.5 ($1.50/$7.50) is its strongest
AI API Cost Optimization Strategies
- Prompt caching: OpenAI, Anthropic and Google bill cached prompt tokens at 90–95% off. Cache your system prompts.
- Model routing: Use a cheap fast model (GPT-6 Luna, Gemini 2.5 Flash-Lite) for classification/routing, then only invoke the expensive model when needed.
- Semantic caching: Cache semantically similar requests. Tools like GPTCache can reduce API calls by 30-70%.
- Output length control: Set explicit max_tokens limits. Unconstrained output is the biggest source of surprise costs.
- Batch API: OpenAI, Anthropic and Google offer 50% batch discounts for asynchronous workloads (acceptable for non-real-time tasks).
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