Gemini 3.1 Pro vs Gemini 3.5 Flash-Lite: pricing and benchmarks
Gemini 3.5 Flash-Lite is 85% cheaper on input tokens ($0.30 vs $2.00 per 1M). Gemini 3.5 Flash-Lite is 79% cheaper on output tokens ($2.50 vs $12.00 per 1M). On our document Q&A workload (50,000 questions a month), Gemini 3.5 Flash-Lite costs $195.00 a month versus $1,160 for Gemini 3.1 Pro, 83% less. Gemini 3.1 Pro scores 155.0 on the Epoch Capabilities Index vs 145.1 for Gemini 3.5 Flash-Lite.
Prices verified September 14, 2026.
Which should you choose?
Gemini 3.1 Pro scores 155.0 on the Epoch Capabilities Index vs 145.1 for Gemini 3.5 Flash-Lite.
Gemini 3.1 Pro scores 59.6% on FrontierMath (Tiers 1–3) vs 26.0% for Gemini 3.5 Flash-Lite.
Gemini 3.5 Flash-Lite costs $0.85 per 1M tokens (3:1 input-to-output mix) vs $4.50 for Gemini 3.1 Pro, 81% less.
A trade-off: Gemini 3.1 Pro is 9.9 ECI points more capable but costs 5.3x as much as Gemini 3.5 Flash-Lite.
Pricing and specs
| Gemini 3.1 Pro | Gemini 3.5 Flash-Lite | |
|---|---|---|
| Provider | ||
| API model ID | gemini-3.1-pro-preview | gemini-3.5-flash-lite |
| Input / 1M tokens | $2.00 | $0.30 |
| Cached input / 1M tokens | $0.20 | $0.03 |
| Output / 1M tokens | $12.00 | $2.50 |
| Long-context rates | $4.00 in / $18.00 out above 200K prompt tokens | — |
| Context window | 1.05M tokens | 1.05M tokens |
| Max output | 66K tokens | 66K tokens |
| Batch discount | — | 50% off |
Benchmarks
| Gemini 3.1 Pro | Gemini 3.5 Flash-Lite | |
|---|---|---|
| Epoch Capabilities Index | 155.0 | 145.1 |
| GPQA Diamond· Science reasoning | 92.6% | 77.8% |
| FrontierMath (Tiers 1–3)· Advanced math | 59.6% | 26.0% |
| SimpleQA Verified· Factual accuracy | 73.5% | — |
| ARC-AGI-2· Abstract reasoning | 77.1% | 10.3% |
| DeepSWE· Coding | 11.7% | — |
| APEX-Agents· Agentic work | 33.5% | — |
Source: Epoch AI, best recorded result per model (CC BY 4.0). A dash means no published score. See all benchmarks
Monthly cost for real workloads
| Workload | Gemini 3.1 Pro | Gemini 3.5 Flash-Lite | Difference |
|---|---|---|---|
Support chatbot 100,000 replies a month, ~1,500 input tokens (system prompt + history) and ~400 output tokens each. | $780.00 | $145.00 | Gemini 3.5 Flash-Lite 81% cheaper |
Document Q&A (RAG) 50,000 questions a month with ~8,000 tokens of retrieved context and ~600 output tokens each. | $1,160 | $195.00 | Gemini 3.5 Flash-Lite 83% cheaper |
Coding agent 10,000 agent steps a month, ~40,000 input tokens each (70% read from the prompt cache) and ~2,000 output tokens. | $536.00 | $94.40 | Gemini 3.5 Flash-Lite 82% cheaper |
Estimates use standard list prices and ignore cache-write surcharges. Different tokenizers can count the same text differently, so test with your own prompts.
Gemini 3.1 Pro vs Gemini 3.5 Flash-Lite cost calculator
- $195.00/mo$0.0039 / request
- Gemini 3.1 ProGoogle$1,160/mo$0.02 / request
Standard-tier list prices. Long-context rates apply automatically where the provider publishes a threshold. Excludes cache-write surcharges, taxes, batch and volume discounts.
Gemini 3.1 Pro pricing notes
Google’s Gemini 3.1 Pro model, currently offered as a preview.
- Prompts over 200K tokens are billed at $4 input / $18 output per 1M tokens.
- No free tier on the Gemini API.
- Output price includes thinking tokens.
Gemini 3.5 Flash-Lite pricing notes
Google’s lowest-cost Gemini 3.5 model for high-volume work.
- The same input price applies to text, image, video and audio.
- Output price includes thinking tokens.
Frequently asked questions
- Is Gemini 3.1 Pro cheaper than Gemini 3.5 Flash-Lite?
- Gemini 3.5 Flash-Lite is 85% cheaper on input tokens ($0.30 vs $2.00 per 1M). Gemini 3.5 Flash-Lite is 79% cheaper on output tokens ($2.50 vs $12.00 per 1M). On our document Q&A workload (50,000 questions a month), Gemini 3.5 Flash-Lite costs $195.00 a month versus $1,160 for Gemini 3.1 Pro, 83% less.
- Which is more capable, Gemini 3.1 Pro or Gemini 3.5 Flash-Lite?
- Gemini 3.1 Pro scores 155.0 on the Epoch Capabilities Index vs 145.1 for Gemini 3.5 Flash-Lite.
- How much does Gemini 3.1 Pro cost per 1M tokens?
- Gemini 3.1 Pro costs $2.00 per 1M input tokens and $12.00 per 1M output tokens, and $0.20 per 1M cached input tokens on Google’s standard tier.
- How much does Gemini 3.5 Flash-Lite cost per 1M tokens?
- Gemini 3.5 Flash-Lite costs $0.30 per 1M input tokens and $2.50 per 1M output tokens, and $0.03 per 1M cached input tokens on Google’s standard tier.
- Which has the larger context window, Gemini 3.1 Pro or Gemini 3.5 Flash-Lite?
- Both offer a 1.05M-token context window.