GPT-5.5 vs Gemini 3.1 Pro Preview: API Pricing Comparison
OpenAI GPT-5.5 vs Google Gemini 3.1 Pro Preview: token prices, batch and cache rates, Arena ELO, and cost per request for 8 business use cases. Prices in USD per 1 million tokens. Data snapshot: 2026-09-06.
GPT-5.5 pricing (OpenAI)
- Input: $5.00 per 1M tokens
- Output: $30.00 per 1M tokens
- Batch API (input/output): $2.50 / $15.00
- Prompt-cache read: $0.50
- Context window: 1M
- Arena ELO: 1477 (as of 2026-09-01)
- Full GPT-5.5 pricing page
Gemini 3.1 Pro Preview pricing (Google)
- Input: $2.00 per 1M tokens
- Output: $12.00 per 1M tokens
- Batch API (input/output): $1.00 / $6.00
- Prompt-cache read: $0.20
- Context window: 1M
- Arena ELO: 1487 (as of 2026-09-01)
- Full Gemini 3.1 Pro Preview pricing page
Cost per request by business use case
List price vs optimized (prompt caching on the cached input share, batch API for async workloads, only where the provider publishes those rates).
| Use case | Tokens (in/out) | GPT-5.5 list | GPT-5.5 optimized | Gemini 3.1 Pro Preview list | Gemini 3.1 Pro Preview optimized |
|---|---|---|---|---|---|
| Support Ticket | 1,500 / 500 | $0.022 | $0.018 | $0.0090 | $0.0074 |
| Knowledge Q&A | 2,000 / 800 | $0.034 | $0.028 | $0.014 | $0.011 |
| Meeting Summary | 10,000 / 1,200 | $0.086 | $0.041 | $0.034 | $0.016 |
| Marketing Content | 2,500 / 1,800 | $0.067 | $0.064 | $0.027 | $0.026 |
| Coding Task | 3,000 / 2,000 | $0.075 | $0.068 | $0.030 | $0.027 |
| Invoice Processing | 1,500 / 600 | $0.025 | $0.012 | $0.010 | $0.0047 |
| Call Summary | 2,000 / 700 | $0.031 | $0.015 | $0.012 | $0.0060 |
| Agent Workflow | 6,000 / 3,000 | $0.120 | $0.101 | $0.048 | $0.040 |
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These are list prices: real cost also depends on caching, batching, negotiated discounts, marketplace agreements, and existing contracts. Get a FinOps review from OptimNow or compare all models.