GPT-6 Sol vs Claude Opus 5 vs Claude Sonnet 5.5
Too close to call on our weighted score (GPT-6 Sol 67, Claude Sonnet 5.5 65, Claude Opus 5 61). The right pick depends on what you value most.
OpenAIGPT-6 Sol
67/100- ECI—
- Price$2.00 / $10.00
- Context1.05M
AnthropicClaude Opus 5
61/100- ECI162.9
- Price$5.00 / $25.00
- Context1M
- Anthropic
Claude Sonnet 5.5
65/100- ECI165.2
- Price$2.00 / $10.00
- Context1M
Too close to call
It is close. Our weighted score puts them within 2 points (GPT-6 Sol 67/100, Claude Sonnet 5.5 65/100, Claude Opus 5 61/100), so choose by what matters most for your work: GPT-6 Sol for raw 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 Sol has no Capabilities Index score yet.
- CapabilityGPT-6 SolShared benchmarks: GPT-6 Sol 86.2% · Claude Opus 5 84.6% · Claude Sonnet 5.5 82.7%
- Lowest priceGPT-6 Sol and Claude Sonnet 5.5GPT-6 Sol $4.00 · Claude Sonnet 5.5 $4.00 · Claude Opus 5 $10.00 per 1M tokens (3:1 blend)
- Longest contextGPT-6 SolGPT-6 Sol 1,050,000 · Claude Opus 5 1,000,000 · Claude Sonnet 5.5 1,000,000 tokens
- Widest inputsSame inputsGPT-6 Sol: Text, Images, PDFs · Claude Opus 5: Text, Images, PDFs · Claude Sonnet 5.5: Text, Images, PDFs
- Self-hostingNo open weightsAll three are available only through APIs
| Measure | Weight | GPT-6 Sol | Claude Opus 5 | Claude Sonnet 5.5 |
|---|---|---|---|---|
| CapabilityShared benchmarks | 50% | 86 | 85 | 83 |
| Price | 25% | 21 | 2 | 21 |
| Inputs & features | 15% | 80 | 80 | 80 |
| Context window | 10% | 61 | 60 | 60 |
| Overall | 100% | 67/100 | 61/100 | 65/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-6 SolOpenAI | Claude Opus 5Anthropic | Claude Sonnet 5.5Anthropic |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | — | 162.9 | 165.2 (best) |
| ECI rank | — | #5 of 148 | #3 of 148 (best) |
| GPQA DiamondGraduate-level science questions | 94.3% | 93.9% | 95.6% (best) |
| FrontierMath Tiers 1–3Research-level mathematics | 89.8% (best) | 85.6% | 88.8% |
| OTIS Mock AIME 2024–2025Competition mathematics | 100% (best) | 98.9% | 100% (best) |
| SimpleQA VerifiedShort factual questions | 60.7% (best) | 59.9% | 46.5% |
| Price per million tokens | |||
| Input | $2.00 (best) | $5.00 | $2.00 (best) |
| Output | $10.00 (best) | $25.00 | $10.00 (best) |
| Cached input | $0.20 (best) | $0.50 | $0.20 (best) |
| Blended (3:1) | $4.00 (best) | $10.00 | $4.00 (best) |
| Long-context rate | Over 272K: $4.00 / $15.00 | Same rate | Same rate |
| Price source | Official OpenAI API | Official Anthropic API | Official Anthropic API |
| Limits | |||
| Context window | 1,050,000 tokens (best) | 1,000,000 tokens | 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 | Yes | Yes | Yes |
| Audio | No | No | No |
| Video | No | No | No |
| Reasoning | Yeslow · medium · high · xhigh · max | 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-6-sol | claude-opus-5 | claude-sonnet-5-5 |
| API providers | 25 | 35 (best) | 23 |
| Released | Sep 22, 2026 | Jul 24, 2026 | Sep 28, 2026 |
| Knowledge cutoff | Apr 20, 2026 | May 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-6 Sol$40.00
- Claude Opus 5$100.00
- Claude Sonnet 5.5$40.00
Which should you choose?
Which is better: GPT-6 Sol, Claude Opus 5 or Claude Sonnet 5.5?
It is close. Our weighted score puts them within 2 points (GPT-6 Sol 67/100, Claude Sonnet 5.5 65/100, Claude Opus 5 61/100), so choose by what matters most for your work: GPT-6 Sol for raw 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 Sol has no Capabilities Index score yet.
Which is cheaper, GPT-6 Sol, Claude Opus 5 or Claude Sonnet 5.5?
GPT-6 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); Claude Opus 5 costs $5.00 input / $25.00 output per million tokens (official Anthropic API price). At a typical mix of three input tokens to one output token, that is $4.00 per million tokens for GPT-6 Sol versus $4.00 for Claude Sonnet 5.5 (1× as much) and $10.00 for Claude Opus 5 (2.5× 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 Sol 86.2%, Claude Opus 5 84.6% and Claude Sonnet 5.5 82.7%. On individual benchmarks: GPQA Diamond — Claude Sonnet 5.5 95.6%, GPT-6 Sol 94.3%, Claude Opus 5 93.9%; FrontierMath Tiers 1–3 — GPT-6 Sol 89.8%, Claude Sonnet 5.5 88.8%, Claude Opus 5 85.6%; OTIS Mock AIME 2024–2025 — GPT-6 Sol 100%, Claude Sonnet 5.5 100%, Claude Opus 5 98.9%; SimpleQA Verified — GPT-6 Sol 60.7%, Claude Opus 5 59.9%, Claude Sonnet 5.5 46.5%.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-6 Sol, Claude Opus 5 and Claude Sonnet 5.5 yet, so there is no like-for-like coding score. On overall capability, GPT-6 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 Sol has the largest context window at 1,050,000 tokens, against 1,000,000 for Claude Opus 5 and 1,000,000 for Claude Sonnet 5.5. Maximum output per response: GPT-6 Sol up to 128,000, Claude Opus 5 up to 128,000, Claude Sonnet 5.5 up to 128,000 tokens.
Which can read images, PDFs, audio or video?
GPT-6 Sol accepts text, images and PDFs; Claude Opus 5 accepts text, images and PDFs; Claude Sonnet 5.5 accepts text, images and PDFs. They handle the same number of input types.
Are any of these open source?
No. GPT-6 Sol, Claude Opus 5 and Claude Sonnet 5.5 are proprietary and only available through APIs and apps.
Which is newer?
Claude Sonnet 5.5 is the newest, released Sep 28, 2026. GPT-6 Sol came out Sep 22, 2026; Claude Opus 5 came out Jul 24, 2026. Knowledge cutoff: GPT-6 Sol Apr 20, 2026, Claude Opus 5 May 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.
