Gemini 3.5 Flash vs GPT-6.1 Sol: pricing and benchmarks
Gemini 3.5 Flash is 25% cheaper on input tokens ($1.50 vs $2.00 per 1M). Gemini 3.5 Flash is 10% cheaper on output tokens ($9.00 vs $10.00 per 1M). On our document Q&A workload (50,000 questions a month), Gemini 3.5 Flash costs $870.00 a month versus $1,100 for GPT-6.1 Sol, 21% less. Epoch AI has not published a capability index score for GPT-6.1 Sol yet.
Prices verified October 3, 2026.
Which should you choose?
Epoch AI has not published a capability index score for GPT-6.1 Sol yet.
Gemini 3.5 Flash costs $3.375 per 1M tokens (3:1 input-to-output mix) vs $4.00 for GPT-6.1 Sol, 16% less.
Pricing and specs
| Gemini 3.5 Flash | GPT-6.1 Sol | |
|---|---|---|
| Provider | OpenAI | |
| API model ID | gemini-3.5-flash | gpt-6.1-sol |
| Input / 1M tokens | $1.50 | $2.00 |
| Cached input / 1M tokens | $0.15 | $0.10 |
| Output / 1M tokens | $9.00 | $10.00 |
| Long-context rates | — | $4.00 in / $15.00 out above 272K prompt tokens |
| Context window | 1.05M tokens | 1.05M tokens |
| Max output | 66K tokens | 128K tokens |
| Batch discount | 50% off | 50% off |
Benchmarks
| Gemini 3.5 Flash | GPT-6.1 Sol | |
|---|---|---|
| Epoch Capabilities Index | 154.7 | — |
| GPQA Diamond· Science reasoning | 90.4% | — |
| FrontierMath (Tiers 1–3)· Advanced math | 62.8% | — |
| SimpleQA Verified· Factual accuracy | 66.2% | — |
| ARC-AGI-2· Abstract reasoning | 72.1% | — |
| DeepSWE· Coding | 37.4% | — |
| APEX-Agents· Agentic work | — | — |
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 3.5 Flash | GPT-6.1 Sol | Difference |
|---|---|---|---|
Support chatbot 100,000 replies a month, ~1,500 input tokens (system prompt + history) and ~400 output tokens each. | $585.00 | $700.00 | Gemini 3.5 Flash 16% cheaper |
Document Q&A (RAG) 50,000 questions a month with ~8,000 tokens of retrieved context and ~600 output tokens each. | $870.00 | $1,100 | Gemini 3.5 Flash 21% 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. | $402.00 | $468.00 | Gemini 3.5 Flash 14% 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 3.5 Flash vs GPT-6.1 Sol cost calculator
- $870.00/mo$0.02 / request
- GPT-6.1 SolOpenAI$1,100/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 3.5 Flash pricing notes
Google’s Gemini 3.5 Flash model, with thinking, tool use and a 1M-token context window.
- Output price includes thinking tokens.
- Context cache storage costs $1.00 per 1M tokens per hour.
- Priority inference costs 1.8x the standard rate.
GPT-6.1 Sol pricing notes
OpenAI’s update to GPT-6 Sol, with near-Astra performance for complex work at a lower cost.
- Cached input costs $0.10 per 1M tokens, half of GPT-6 Sol’s $0.20.
- Cache writes are billed at $2.50 per 1M tokens.
- Prompts over 272K input tokens use the long-context rates.
- Fast mode costs 2x the standard rate; Flex costs half.
Frequently asked questions
- Is Gemini 3.5 Flash cheaper than GPT-6.1 Sol?
- Gemini 3.5 Flash is 25% cheaper on input tokens ($1.50 vs $2.00 per 1M). Gemini 3.5 Flash is 10% cheaper on output tokens ($9.00 vs $10.00 per 1M). On our document Q&A workload (50,000 questions a month), Gemini 3.5 Flash costs $870.00 a month versus $1,100 for GPT-6.1 Sol, 21% less.
- Which is more capable, Gemini 3.5 Flash or GPT-6.1 Sol?
- Epoch AI has not published a capability index score for GPT-6.1 Sol yet.
- How much does Gemini 3.5 Flash cost per 1M tokens?
- Gemini 3.5 Flash costs $1.50 per 1M input tokens and $9.00 per 1M output tokens, and $0.15 per 1M cached input tokens on Google’s standard tier.
- How much does GPT-6.1 Sol cost per 1M tokens?
- GPT-6.1 Sol costs $2.00 per 1M input tokens and $10.00 per 1M output tokens, and $0.10 per 1M cached input tokens on OpenAI’s standard tier.
- Which has the larger context window, Gemini 3.5 Flash or GPT-6.1 Sol?
- GPT-6.1 Sol has the larger context window: 1.05M tokens versus 1.05M for Gemini 3.5 Flash.