Gemini 3.1 Pro Preview Custom Tools vs GPT-5.5: API Cost Comparison
Compare the API pricing, context windows, features, and real-world cost projections for Gemini 3.1 Pro Preview Custom Tools (Google) and GPT-5.5 (OpenAI). Use the interactive calculator below to compute your exact monthly cost based on your token usage and request volume.
Prices verified Apr 30, 2026
Interactive Cost Calculator
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Showing costs for 2 models. Cheapest: Gemini 3.1 Pro Preview Custom Tools at $80.00/month.
| Alert | |||||||
|---|---|---|---|---|---|---|---|
BestGemini 3.1 Pro Preview Custom Tools | $80.00 | $0.008000 | $20.00 | $60.00 | 60.0% | Alerts coming soon | |
GPT-5.5 | OpenAI | $200.00 | $0.020000 | $50.00 | $150.00 | — | Alerts coming soon |
Monthly Cost Comparison
Price Comparison at a Glance
All prices are in USD per 1 million tokens ($/M tokens). Lower is cheaper.
| Pricing Type | Gemini 3.1 Pro Preview Custom Tools | GPT-5.5 | Cheaper |
|---|---|---|---|
| Input (standard) | $2.00/M | $5.00/M | Gemini 3.1 Pro Preview Custom Tools |
| Output | $12.00/M | $30.00/M | Gemini 3.1 Pro Preview Custom Tools |
Prices last verified: 2026-03-27 – 2026-04-30
Cost Breakdown by Usage Volume
Estimated monthly costs at different request volumes, assuming 1,000 input tokens and 500 output tokens per request. Adjust in the calculator above for your specific use case.
| Volume | Gemini 3.1 Pro Preview Custom ToolsMonthly | GPT-5.5Monthly | Gemini 3.1 Pro Preview Custom ToolsPer request | GPT-5.5Per request |
|---|---|---|---|---|
| 1K requests/mo | $8.00 | $20.00 | $0.008000 | $0.020000 |
| 10K requests/mo | $80.00 | $200.00 | $0.008000 | $0.020000 |
| 100K requests/mo | $800.00 | $2,000.00 | $0.008000 | $0.020000 |
| 1M requests/mo | $8,000.00 | $20,000.00 | $0.008000 | $0.020000 |
Green values indicate the lower-cost option at each volume tier. Cost per request is calculated at 1,000 input + 500 output tokens using standard (non-batch, non-cached) pricing.
Price History
Input price per 1M tokensWhen to Choose Gemini 3.1 Pro Preview Custom Tools
by Google
- General chatbot
Input / 1M tokens
$2.00/M
Output / 1M tokens
$12.00/M
Context window
1,048,576
Tier
mid
When to Choose GPT-5.5
by OpenAI
- General chatbot
Input / 1M tokens
$5.00/M
Output / 1M tokens
$30.00/M
Context window
1,050,000
Tier
premium
Key Differences Beyond Price
Cost is only one factor in choosing an AI model. Context window size, rate limits, supported features, and latency all affect whether a model fits your use case.
| Capability | Gemini 3.1 Pro Preview Custom Tools | GPT-5.5 |
|---|---|---|
| Context window | 1,048,576 tokens | 1,050,000 tokens |
| Max output tokens | 65,536 tokens | 128,000 tokens |
| Performance tier | Mid | Premium |
| Vision / image input | Yes | Yes |
| Function calling | Yes | Yes |
| JSON mode | Yes | Yes |
| Prompt caching | No | No |
| Batch API (50% discount) | No | No |
| Extended reasoning | No | Yes |
| Fine-tuning | No | No |
Frequently Asked Questions
Is Gemini 3.1 Pro Preview Custom Tools cheaper than GPT-5.5?
At standard usage (1,000 input tokens, 500 output tokens, 100,000 requests/month), Gemini 3.1 Pro Preview Custom Tools costs $800.00/month versus $2,000.00/month for GPT-5.5 — a 60% saving. Your actual savings will vary based on your token profile; output-heavy workloads amplify differences in output pricing.
Which model has a larger context window, Gemini 3.1 Pro Preview Custom Tools or GPT-5.5?
GPT-5.5 has a larger context window at 1,050,000 tokens, compared to 1,048,576 tokens for Gemini 3.1 Pro Preview Custom Tools. A larger context window is important for processing long documents, multi-turn conversations, or large codebases without truncation.
Do Gemini 3.1 Pro Preview Custom Tools and GPT-5.5 support the Batch API?
Neither Gemini 3.1 Pro Preview Custom Tools nor GPT-5.5 currently supports a batch API with discounted pricing. For batch-eligible alternatives, consider models from OpenAI, Anthropic, or Google that include batch API support.
Which model offers better prompt caching?
Neither Gemini 3.1 Pro Preview Custom Tools nor GPT-5.5 currently supports prompt caching. For prompt-caching capable alternatives, consider Claude models from Anthropic or GPT-4o from OpenAI.
What are the best use cases for Gemini 3.1 Pro Preview Custom Tools vs GPT-5.5?
Both models are well-suited for General chatbot. Gemini 3.1 Pro Preview Custom Tools is particularly strong for overlapping tasks. GPT-5.5 is favored for similar workflows. At the same quality level, the lower-cost model is usually preferable; use this page's calculator to compare total monthly spend at your volume.
What is the cost per request for Gemini 3.1 Pro Preview Custom Tools vs GPT-5.5?
At 1,000 input tokens and 500 output tokens per request — a typical conversational workload — Gemini 3.1 Pro Preview Custom Tools costs $0.008000 per request and GPT-5.5 costs $0.020000 per request. At 100,000 requests/month, that translates to $800.00 and $2,000.00 respectively. Use the interactive calculator to adjust these parameters for your actual workload.
Gemini 3.1 Pro Preview Custom Tools vs GPT-5.5: Summary
When comparing Gemini 3.1 Pro Preview Custom Tools and GPT-5.5 for API cost, the right choice depends on your workload's token profile, required features, and tolerance for latency. Gemini 3.1 Pro Preview Custom Tools offers lower total cost at standard usage volumes (1,000 input + 500 output tokens per request at 100,000 requests/month) at $800.00/month, compared to $2,000.00/month for GPT-5.5.
Both models are priced in USD per million tokens, the standard unit across all major AI API providers. Gemini 3.1 Pro Preview Custom Tools charges $2.00/M for input tokens and $12.00/M for output tokens. GPT-5.5 charges $5.00/M input and $30.00/M output. If your workload is output-heavy (more tokens generated than consumed as input), the model with the lower output price compounds cost savings significantly at scale.
Context window capacity differs between the two: GPT-5.5 supports up to 1,050,000 tokens in a single request, versus 1,048,576 tokens for Gemini 3.1 Pro Preview Custom Tools. A larger context window is essential for document summarization, large codebase analysis, and multi-document retrieval-augmented generation (RAG) applications.
Use the interactive calculator at the top of this page to enter your actual token usage and monthly request volume for a precise cost comparison tailored to your workload. Adjust for batch API discounts and prompt caching to find the most cost-effective option for your specific deployment.
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Relevant Use Cases
See cost recommendations for workloads where Gemini 3.1 Pro Preview Custom Tools or GPT-5.5 is recommended.