Gemini 3.8 Flash vs GPT-6.1 Sol vs Claude Sonnet 5.5
Gemini 3.8 Flash comes out ahead, 73 to 69 and 65 on our weighted score, and it is the cheaper option too.
- Our pick
GoogleGemini 3.8 Flash
73/100- ECI156.9
- Price$0.75 / $3.75
- Context1.05M
OpenAIGPT-6.1 Sol
69/100- ECI—
- Price$2.00 / $10.00
- Context1.05M
AnthropicClaude Sonnet 5.5
65/100- ECI165.2
- Price$2.00 / $10.00
- Context1M
Gemini 3.8 Flash is our pick
Gemini 3.8 Flash is the better all-round choice, scoring 73/100 against GPT-6.1 Sol (69) and Claude Sonnet 5.5 (65). It leads on price and inputs & features. GPT-6.1 Sol wins on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%. Capability uses the average of shared benchmarks (GPQA Diamond, FrontierMath Tiers 1–3, OTIS Mock AIME 2024–2025 and SimpleQA Verified), because GPT-6.1 Sol has no Capabilities Index score yet.
- CapabilityGPT-6.1 SolShared benchmarks: GPT-6.1 Sol 90.7% · Gemini 3.8 Flash 83.1% · Claude Sonnet 5.5 82.7%
- Lowest priceGemini 3.8 FlashGemini 3.8 Flash $1.50 · GPT-6.1 Sol $4.00 · Claude Sonnet 5.5 $4.00 per 1M tokens (3:1 blend)
- Longest contextGPT-6.1 Sol and Gemini 3.8 FlashGPT-6.1 Sol 1,050,000 · Gemini 3.8 Flash 1,048,576 · Claude Sonnet 5.5 1,000,000 tokens
- Widest inputsGemini 3.8 FlashGemini 3.8 Flash: Text, Images, PDFs, Audio, Video · GPT-6.1 Sol: Text, Images, PDFs · Claude Sonnet 5.5: Text, Images, PDFs
- Self-hostingNo open weightsAll three are available only through APIs
| Measure | Weight | Gemini 3.8 Flash | GPT-6.1 Sol | Claude Sonnet 5.5 |
|---|---|---|---|---|
| CapabilityShared benchmarks | 50% | 83 | 91 | 83 |
| Price | 25% | 42 | 21 | 21 |
| Inputs & features | 15% | 100 | 80 | 80 |
| Context window | 10% | 61 | 61 | 60 |
| Overall | 100% | 73/100 | 69/100 | 65/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Gemini 3.8 FlashGoogle | GPT-6.1 SolOpenAI | Claude Sonnet 5.5Anthropic |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 156.9 | — | 165.2 (best) |
| ECI rank | #15 of 148 | — | #3 of 148 (best) |
| GPQA DiamondGraduate-level science questions | 95.4% | 95.4% | 95.6% (best) |
| FrontierMath Tiers 1–3Research-level mathematics | 68.4% | 93.7% (best) | 88.8% |
| OTIS Mock AIME 2024–2025Competition mathematics | 98.9% | 100% (best) | 100% (best) |
| SimpleQA VerifiedShort factual questions | 69.7% | 73.9% (best) | 46.5% |
| Price per million tokens | |||
| Input | $0.75 (best) | $2.00 | $2.00 |
| Output | $3.75 (best) | $10.00 | $10.00 |
| Cached input | $0.075 (best) | $0.10 | $0.20 |
| Blended (3:1) | $1.50 (best) | $4.00 | $4.00 |
| Long-context rate | Same rate | Over 272K: $4.00 / $15.00 | Same rate |
| Price source | Official Google API | Official OpenAI API | Official Anthropic API |
| Limits | |||
| Context window | 1,048,576 tokens | 1,050,000 tokens (best) | 1,000,000 tokens |
| Max output | 65,536 tokens | 128,000 tokens (best) | 128,000 tokens (best) |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | Yes | Yes |
| Audio | Yes | No | No |
| Video | Yes | No | No |
| Reasoning | Yeslow · medium · high | Yeslow · medium · high · xhigh · max | Yeslow · medium · high · xhigh · max |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Proprietary | Proprietary |
| API model ID | gemini-3.8-flash | gpt-6.1-sol | claude-sonnet-5-5 |
| API providers | 21 | 21 | 23 (best) |
| Released | Sep 2, 2026 | Sep 29, 2026 | Sep 28, 2026 |
| Knowledge cutoff | — | Apr 30, 2026 | Jun 2026 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Gemini 3.8 Flash$15.00
- GPT-6.1 Sol$40.00
- Claude Sonnet 5.5$40.00
Which should you choose?
Which is better: Gemini 3.8 Flash, GPT-6.1 Sol or Claude Sonnet 5.5?
Gemini 3.8 Flash is the better all-round choice, scoring 73/100 against GPT-6.1 Sol (69) and Claude Sonnet 5.5 (65). It leads on price and inputs & features. GPT-6.1 Sol wins on capability. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%. Capability uses the average of shared benchmarks (GPQA Diamond, FrontierMath Tiers 1–3, OTIS Mock AIME 2024–2025 and SimpleQA Verified), because GPT-6.1 Sol has no Capabilities Index score yet.
Which is cheaper, Gemini 3.8 Flash, GPT-6.1 Sol or Claude Sonnet 5.5?
Gemini 3.8 Flash is cheaper at $0.75 input / $3.75 output per million tokens (official Google API price). GPT-6.1 Sol costs $2.00 input / $10.00 output per million tokens (official OpenAI API price); Claude Sonnet 5.5 costs $2.00 input / $10.00 output per million tokens (official Anthropic API price). At a typical mix of three input tokens to one output token, that is $1.50 per million tokens for Gemini 3.8 Flash versus $4.00 for GPT-6.1 Sol (2.7× as much) and $4.00 for Claude Sonnet 5.5 (2.7× as much).
Which scores higher on benchmarks?
Not every model here has a Capabilities Index score, so we compare the average of shared benchmarks (GPQA Diamond, FrontierMath Tiers 1–3, OTIS Mock AIME 2024–2025 and SimpleQA Verified): GPT-6.1 Sol 90.7%, Gemini 3.8 Flash 83.1% and Claude Sonnet 5.5 82.7%. On individual benchmarks: GPQA Diamond — Claude Sonnet 5.5 95.6%, Gemini 3.8 Flash 95.4%, GPT-6.1 Sol 95.4%; FrontierMath Tiers 1–3 — GPT-6.1 Sol 93.7%, Claude Sonnet 5.5 88.8%, Gemini 3.8 Flash 68.4%; OTIS Mock AIME 2024–2025 — GPT-6.1 Sol 100%, Claude Sonnet 5.5 100%, Gemini 3.8 Flash 98.9%; SimpleQA Verified — GPT-6.1 Sol 73.9%, Gemini 3.8 Flash 69.7%, Claude Sonnet 5.5 46.5%.
Which is better for coding?
There are no published SWE-bench Verified results for Gemini 3.8 Flash, GPT-6.1 Sol and Claude Sonnet 5.5 yet, so there is no like-for-like coding score. On overall capability, GPT-6.1 Sol leads, which tends to carry over to coding, but test on your own codebase. All three support tool calling for agent workflows.
Which has the bigger context window?
GPT-6.1 Sol and Gemini 3.8 Flash have the largest context windows (1,050,000 and 1,048,576 tokens), against 1,000,000 for Claude Sonnet 5.5. Maximum output per response: Gemini 3.8 Flash up to 65,536, GPT-6.1 Sol up to 128,000, Claude Sonnet 5.5 up to 128,000 tokens.
Which can read images, PDFs, audio or video?
Gemini 3.8 Flash accepts text, images, PDFs, audio and video; GPT-6.1 Sol accepts text, images and PDFs; Claude Sonnet 5.5 accepts text, images and PDFs. Gemini 3.8 Flash handles the widest range of inputs.
Are any of these open source?
No. Gemini 3.8 Flash, GPT-6.1 Sol and Claude Sonnet 5.5 are proprietary and only available through APIs and apps.
Which is newer?
GPT-6.1 Sol is the newest, released Sep 29, 2026. Claude Sonnet 5.5 came out Sep 28, 2026; Gemini 3.8 Flash came out Sep 2, 2026. Knowledge cutoff: GPT-6.1 Sol Apr 30, 2026, Claude Sonnet 5.5 Jun 2026.
How do you decide the winner?
Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Oct 4, 2026.
