Gemini 3.5 Flash vs Gemini 3.1 Pro
Google's mid-tier siblings go head-to-head. Flash is 25% cheaper on both input and output — with the same 1M context. See which fits your workload.
Pricing data verified: 2026-06-20
| Specification | Gemini 3.5 Flash (Google) | Gemini 3.1 Pro (Google) |
|---|---|---|
| Input Price (per 1M tokens) | $1.50 | $2.00 |
| Output Price (per 1M tokens) | $9.00 | $12.00 |
| Context Window | 1M | 1M |
| Tier | Mid | Mid |
| Provider |
Calculate Your Exact Costs
See how the costs stack up for your specific usage pattern.
Other Models to Consider
Which Model for Which Use Case?
High-Volume Chatbots
Gemini 3.5 Flash's 25% cheaper pricing makes it the clear winner for chatbots handling thousands of daily conversations. Same 1M context, lower cost per message.
Complex Reasoning
Gemini 3.1 Pro's enhanced reasoning capabilities may justify the 25% premium for tasks requiring nuanced analysis, multi-step logic, or sophisticated function calling.
Long Document Processing
Both models share the same 1M token context window, making them equally capable for long documents, codebases, and extended conversations. Flash gets you there cheaper.
Enterprise Integration
Gemini 3.1 Pro may offer better enterprise features, compliance options, and support SLAs. If your organization needs enterprise-grade reliability, Pro is the safer choice.
Comparing Google Models?
APIpulse Pro lets you compare all 42 models, find the cheapest option for your exact usage, and save scenarios for your team.
Frequently Asked Questions
Is Gemini 3.5 Flash cheaper than Gemini 3.1 Pro?
Yes. Gemini 3.5 Flash is 25% cheaper on both input and output: $1.50/M input vs $2.00/M, and $9.00/M output vs $12.00/M. Both share the same 1M token context window.
When should I choose Gemini 3.1 Pro over Gemini 3.5 Flash?
Choose Gemini 3.1 Pro for complex reasoning tasks, enterprise features, and situations where output quality matters more than cost. Pro may have better reasoning capabilities for nuanced analysis.
Do they have the same context window?
Yes, both Gemini 3.5 Flash and Gemini 3.1 Pro have a 1M token context window, making them equally capable for long document processing and extended conversations.
Can Gemini 3.5 Flash match Gemini 3.1 Pro quality?
For most tasks like chatbots, content generation, and classification, Gemini 3.5 Flash delivers comparable quality at 25% less cost. Pro edges ahead on complex reasoning and enterprise use cases.