GPT-5.2 vs GPT-6.1 Sol vs Claude Sonnet 5.5
GPT-6.1 Sol comes out ahead, 69 to 65 and 56 on our weighted score.
OpenAIGPT-5.2
56/100- ECI153.5
- Price$1.75 / $14.00
- Context400K
- Our pickOpenAI
GPT-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
GPT-6.1 Sol is our pick
GPT-6.1 Sol is the better all-round choice, scoring 69/100 against Claude Sonnet 5.5 (65) and GPT-5.2 (56). It leads 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% · Claude Sonnet 5.5 82.7% · GPT-5.2 73.0%
- Lowest priceGPT-6.1 Sol and Claude Sonnet 5.5GPT-6.1 Sol $4.00 · Claude Sonnet 5.5 $4.00 · GPT-5.2 $4.81 per 1M tokens (3:1 blend)
- Longest contextGPT-6.1 SolGPT-6.1 Sol 1,050,000 · Claude Sonnet 5.5 1,000,000 · GPT-5.2 400,000 tokens
- Widest inputsGPT-6.1 Sol and Claude Sonnet 5.5GPT-5.2: Text, Images · 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 | GPT-5.2 | GPT-6.1 Sol | Claude Sonnet 5.5 |
|---|---|---|---|---|
| CapabilityShared benchmarks | 50% | 73 | 91 | 83 |
| Price | 25% | 18 | 21 | 21 |
| Inputs & features | 15% | 70 | 80 | 80 |
| Context window | 10% | 44 | 61 | 60 |
| Overall | 100% | 56/100 | 69/100 | 65/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-5.2OpenAI | GPT-6.1 SolOpenAI | Claude Sonnet 5.5Anthropic |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 153.5 | — | 165.2 (best) |
| ECI rank | #38 of 148 | — | #3 of 148 (best) |
| GPQA DiamondGraduate-level science questions | 91.4% | 95.4% | 95.6% (best) |
| FrontierMath Tiers 1–3Research-level mathematics | 67.4% | 93.7% (best) | 88.8% |
| OTIS Mock AIME 2024–2025Competition mathematics | 96.1% | 100% (best) | 100% (best) |
| SWE-bench VerifiedFixing real GitHub issues | 73.8% | — | — |
| SimpleQA VerifiedShort factual questions | 37.1% | 73.9% (best) | 46.5% |
| Price per million tokens | |||
| Input | $1.75 (best) | $2.00 | $2.00 |
| Output | $14.00 | $10.00 (best) | $10.00 (best) |
| Cached input | $0.175 | $0.10 (best) | $0.20 |
| Blended (3:1) | $4.81 | $4.00 (best) | $4.00 (best) |
| Long-context rate | Same rate | Over 272K: $4.00 / $15.00 | Same rate |
| Price source | Official OpenAI API | Official OpenAI API | Official Anthropic API |
| Limits | |||
| Context window | 400,000 tokens | 1,050,000 tokens (best) | 1,000,000 tokens |
| Max output | 128,000 tokens | 128,000 tokens | 128,000 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | No | Yes | Yes |
| Audio | No | No | No |
| Video | No | No | No |
| Reasoning | Yeslow · medium · high · xhigh | 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 | gpt-5.2 | gpt-6.1-sol | claude-sonnet-5-5 |
| API providers | 21 | 21 | 23 (best) |
| Released | Dec 11, 2025 | Sep 29, 2026 | Sep 28, 2026 |
| Knowledge cutoff | Aug 31, 2025 | 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.
- GPT-5.2$45.50
- GPT-6.1 Sol$40.00
- Claude Sonnet 5.5$40.00
Which should you choose?
Which is better: GPT-5.2, GPT-6.1 Sol or Claude Sonnet 5.5?
GPT-6.1 Sol is the better all-round choice, scoring 69/100 against Claude Sonnet 5.5 (65) and GPT-5.2 (56). It leads 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, GPT-5.2, GPT-6.1 Sol or Claude Sonnet 5.5?
GPT-6.1 Sol is cheaper at $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); GPT-5.2 costs $1.75 input / $14.00 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $4.00 per million tokens for GPT-6.1 Sol versus $4.00 for Claude Sonnet 5.5 (1× as much) and $4.81 for GPT-5.2 (1.2× 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%, Claude Sonnet 5.5 82.7% and GPT-5.2 73.0%. On individual benchmarks: GPQA Diamond — Claude Sonnet 5.5 95.6%, GPT-6.1 Sol 95.4%, GPT-5.2 91.4%; FrontierMath Tiers 1–3 — GPT-6.1 Sol 93.7%, Claude Sonnet 5.5 88.8%, GPT-5.2 67.4%; OTIS Mock AIME 2024–2025 — GPT-6.1 Sol 100%, Claude Sonnet 5.5 100%, GPT-5.2 96.1%; SimpleQA Verified — GPT-6.1 Sol 73.9%, Claude Sonnet 5.5 46.5%, GPT-5.2 37.1%.
Which is better for coding?
There are no published SWE-bench Verified results for 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 has the largest context window at 1,050,000 tokens, against 1,000,000 for Claude Sonnet 5.5 and 400,000 for GPT-5.2. Maximum output per response: GPT-5.2 up to 128,000, 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?
GPT-5.2 accepts text and images; GPT-6.1 Sol accepts text, images and PDFs; Claude Sonnet 5.5 accepts text, images and PDFs. GPT-6.1 Sol handles the widest range of inputs.
Are any of these open source?
No. GPT-5.2, 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; GPT-5.2 came out Dec 11, 2025. Knowledge cutoff: GPT-5.2 Aug 31, 2025, 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.
