Claude Sonnet 5.5 vs Muse Spark 1.3 vs GPT-6.1 Sol
Too close to call on our weighted score (Muse Spark 1.3 73, GPT-6.1 Sol 72, Claude Sonnet 5.5 70). The right pick depends on what you value most.
AnthropicClaude Sonnet 5.5
70/100- ECI165.2
- Price$2.00 / $10.00
- Context1M
MetaMuse Spark 1.3
73/100- ECI156.9
- Price$1.25 / $4.25
- Context1.05M
OpenAIGPT-6.1 Sol
72/100- ECI—
- Price$2.00 / $10.00
- Context1.05M
Too close to call
It is close. Our weighted score puts them within 2 points (Muse Spark 1.3 73/100, GPT-6.1 Sol 72/100, Claude Sonnet 5.5 70/100), so choose by what matters most for your work: GPT-6.1 Sol for raw capability and Muse Spark 1.3 on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%. Capability uses the average of shared benchmarks (FrontierMath Tiers 1–3 and OTIS Mock AIME 2024–2025), because GPT-6.1 Sol has no Capabilities Index score yet.
- CapabilityGPT-6.1 SolShared benchmarks: GPT-6.1 Sol 96.8% · Claude Sonnet 5.5 94.4% · Muse Spark 1.3 86.8%
- Lowest priceMuse Spark 1.3Muse Spark 1.3 $2.00 · Claude Sonnet 5.5 $4.00 · GPT-6.1 Sol $4.00 per 1M tokens (3:1 blend)
- Longest contextGPT-6.1 Sol and Muse Spark 1.3GPT-6.1 Sol 1,050,000 · Muse Spark 1.3 1,048,576 · Claude Sonnet 5.5 1,000,000 tokens
- Widest inputsMuse Spark 1.3Claude Sonnet 5.5: Text, Images, PDFs · Muse Spark 1.3: Text, Images, PDFs, Audio, Video · GPT-6.1 Sol: Text, Images, PDFs
- Self-hostingNo open weightsAll three are available only through APIs
| Measure | Weight | Claude Sonnet 5.5 | Muse Spark 1.3 | GPT-6.1 Sol |
|---|---|---|---|---|
| CapabilityShared benchmarks | 50% | 94 | 87 | 97 |
| Price | 25% | 21 | 36 | 21 |
| Inputs & features | 15% | 80 | 100 | 80 |
| Context window | 10% | 60 | 61 | 61 |
| Overall | 100% | 70/100 | 73/100 | 72/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | Claude Sonnet 5.5Anthropic | Muse Spark 1.3Meta | GPT-6.1 SolOpenAI |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 165.2 (best) | 156.9 | — |
| ECI rank | #3 of 148 (best) | #17 of 148 | — |
| GPQA DiamondGraduate-level science questions | 95.6% (best) | — | 95.4% |
| FrontierMath Tiers 1–3Research-level mathematics | 88.8% | 74.4% | 93.7% (best) |
| OTIS Mock AIME 2024–2025Competition mathematics | 100% (best) | 99.2% | 100% (best) |
| SimpleQA VerifiedShort factual questions | 46.5% | — | 73.9% (best) |
| Price per million tokens | |||
| Input | $2.00 | $1.25 (best) | $2.00 |
| Output | $10.00 | $4.25 (best) | $10.00 |
| Cached input | $0.20 | $0.15 | $0.10 (best) |
| Blended (3:1) | $4.00 | $2.00 (best) | $4.00 |
| Long-context rate | Same rate | Same rate | Over 272K: $4.00 / $15.00 |
| Price source | Official Anthropic API | Official Meta API | Official OpenAI API |
| Limits | |||
| Context window | 1,000,000 tokens | 1,048,576 tokens | 1,050,000 tokens (best) |
| Max output | 128,000 tokens | 131,072 tokens (best) | 128,000 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | Yes | Yes |
| PDFs | Yes | Yes | Yes |
| Audio | No | Yes | No |
| Video | No | Yes | No |
| Reasoning | Yeslow · medium · high · xhigh · max | Yesminimal · low · 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 | claude-sonnet-5-5 | muse-spark-1.3 | gpt-6.1-sol |
| API providers | 23 (best) | 12 | 21 |
| Released | Sep 28, 2026 | Sep 2, 2026 | Sep 29, 2026 |
| Knowledge cutoff | Jun 2026 | — | Apr 30, 2026 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- Claude Sonnet 5.5$40.00
- Muse Spark 1.3$21.00
- GPT-6.1 Sol$40.00
Which should you choose?
Which is better: Claude Sonnet 5.5, Muse Spark 1.3 or GPT-6.1 Sol?
It is close. Our weighted score puts them within 2 points (Muse Spark 1.3 73/100, GPT-6.1 Sol 72/100, Claude Sonnet 5.5 70/100), so choose by what matters most for your work: GPT-6.1 Sol for raw capability and Muse Spark 1.3 on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%. Capability uses the average of shared benchmarks (FrontierMath Tiers 1–3 and OTIS Mock AIME 2024–2025), because GPT-6.1 Sol has no Capabilities Index score yet.
Which is cheaper, Claude Sonnet 5.5, Muse Spark 1.3 or GPT-6.1 Sol?
Muse Spark 1.3 is cheaper at $1.25 input / $4.25 output per million tokens (official Meta API price). Claude Sonnet 5.5 costs $2.00 input / $10.00 output per million tokens (official Anthropic API price); GPT-6.1 Sol costs $2.00 input / $10.00 output per million tokens (official OpenAI API price). At a typical mix of three input tokens to one output token, that is $2.00 per million tokens for Muse Spark 1.3 versus $4.00 for Claude Sonnet 5.5 (2× as much) and $4.00 for GPT-6.1 Sol (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 (FrontierMath Tiers 1–3 and OTIS Mock AIME 2024–2025): GPT-6.1 Sol 96.8%, Claude Sonnet 5.5 94.4% and Muse Spark 1.3 86.8%. On individual benchmarks: FrontierMath Tiers 1–3 — GPT-6.1 Sol 93.7%, Claude Sonnet 5.5 88.8%, Muse Spark 1.3 74.4%; OTIS Mock AIME 2024–2025 — Claude Sonnet 5.5 100%, GPT-6.1 Sol 100%, Muse Spark 1.3 99.2%.
Which is better for coding?
There are no published SWE-bench Verified results for Claude Sonnet 5.5, Muse Spark 1.3 and GPT-6.1 Sol 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 Muse Spark 1.3 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: Claude Sonnet 5.5 up to 128,000, Muse Spark 1.3 up to 131,072, GPT-6.1 Sol up to 128,000 tokens.
Which can read images, PDFs, audio or video?
Claude Sonnet 5.5 accepts text, images and PDFs; Muse Spark 1.3 accepts text, images, PDFs, audio and video; GPT-6.1 Sol accepts text, images and PDFs. Muse Spark 1.3 handles the widest range of inputs.
Are any of these open source?
No. Claude Sonnet 5.5, Muse Spark 1.3 and GPT-6.1 Sol 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; Muse Spark 1.3 came out Sep 2, 2026. Knowledge cutoff: Claude Sonnet 5.5 Jun 2026, GPT-6.1 Sol Apr 30, 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.
