GPT-6.1 Sol vs GLM-5.3 vs Claude Sonnet 5.5
Too close to call on our weighted score (GPT-6.1 Sol 72, Claude Sonnet 5.5 72, GLM-5.3 63). The right pick depends on what you value most.
OpenAIGPT-6.1 Sol
72/100- ECI167.8
- Price$2.00 / $10.00
- Context1.05M
Z.ai (Zhipu)GLM-5.3
63/100- ECI156.2
- Price$1.40 / $4.40
- Context1M
AnthropicClaude Sonnet 5.5
72/100- ECI166.7
- Price$2.00 / $10.00
- Context1M
Too close to call
It is close. Our weighted score puts them within a point (GPT-6.1 Sol 72/100, Claude Sonnet 5.5 72/100, GLM-5.3 63/100), so choose by what matters most for your work: GPT-6.1 Sol for raw capability and GLM-5.3 on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityGPT-6.1 SolCapabilities Index (ECI): GPT-6.1 Sol 167.8 · Claude Sonnet 5.5 166.7 · GLM-5.3 156.2
- Lowest priceGLM-5.3GLM-5.3 $2.15 · GPT-6.1 Sol $4.00 · Claude Sonnet 5.5 $4.00 per 1M tokens (3:1 blend)
- Longest contextGPT-6.1 SolGPT-6.1 Sol 1,050,000 · GLM-5.3 1,000,000 · Claude Sonnet 5.5 1,000,000 tokens
- Widest inputsGPT-6.1 Sol and Claude Sonnet 5.5GPT-6.1 Sol: Text, Images, PDFs · GLM-5.3: Text · Claude Sonnet 5.5: Text, Images, PDFs
- Self-hostingGLM-5.3Publishes downloadable weights
| Measure | Weight | GPT-6.1 Sol | GLM-5.3 | Claude Sonnet 5.5 |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 99 | 84 | 97 |
| Price | 25% | 20 | 33 | 20 |
| Inputs & features | 15% | 80 | 45 | 80 |
| Context window | 10% | 61 | 60 | 60 |
| Overall | 100% | 72/100 | 63/100 | 72/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GPT-6.1 SolOpenAI | GLM-5.3Z.ai (Zhipu) | Claude Sonnet 5.5Anthropic |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 167.8 (best) | 156.2 | 166.7 |
| ECI rank | #4 of 165 (best) | #33 of 165 | #5 of 165 |
| GPQA DiamondGraduate-level science questions | 95.4% | 90.9% | 95.6% (best) |
| FrontierMath Tiers 1–3Research-level mathematics | 93.7% (best) | 68.8% | 88.8% |
| OTIS Mock AIME 2024–2025Competition mathematics | 100% (best) | 91.1% | 100% (best) |
| SimpleQA VerifiedShort factual questions | 73.9% (best) | 41.0% | 46.5% |
| Price per million tokens | |||
| Input | $2.00 | $1.40 (best) | $2.00 |
| Output | $10.00 | $4.40 (best) | $10.00 |
| Cached input | $0.10 (best) | $0.26 | $0.10 (best) |
| Blended (3:1) | $4.00 | $2.15 (best) | $4.00 |
| Long-context rate | Over 272K: $4.00 / $15.00 | Same rate | Same rate |
| Price source | Official OpenAI API | Official Z.AI 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 | 131,072 tokens (best) | 128,000 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | Yes | No | Yes |
| PDFs | Yes | No | Yes |
| Audio | No | No | No |
| Video | No | No | No |
| Reasoning | Yeslow · medium · high · xhigh · max | Yeslow · high · max | Yeslow · medium · high · xhigh · max |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Proprietary | Open | Proprietary |
| API model ID | gpt-6.1-sol | glm-5.3 | claude-sonnet-5-5 |
| API providers | 33 | 83 (best) | 34 |
| Released | Sep 29, 2026 | Aug 14, 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.
- GPT-6.1 Sol$40.00
- GLM-5.3$22.80
- Claude Sonnet 5.5$40.00
Which should you choose?
Which is better: GPT-6.1 Sol, GLM-5.3 or Claude Sonnet 5.5?
It is close. Our weighted score puts them within a point (GPT-6.1 Sol 72/100, Claude Sonnet 5.5 72/100, GLM-5.3 63/100), so choose by what matters most for your work: GPT-6.1 Sol for raw capability and GLM-5.3 on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, GPT-6.1 Sol, GLM-5.3 or Claude Sonnet 5.5?
GLM-5.3 is cheaper at $1.40 input / $4.40 output per million tokens (official Z.AI 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 $2.15 per million tokens for GLM-5.3 versus $4.00 for GPT-6.1 Sol (1.9× as much) and $4.00 for Claude Sonnet 5.5 (1.9× as much).
Which scores higher on benchmarks?
GPT-6.1 Sol scores higher on the Capabilities Index (ECI): GPT-6.1 Sol 167.8 (#4 of 165), Claude Sonnet 5.5 166.7 (#5 of 165) and GLM-5.3 156.2 (#33 of 165). The confidence ranges of the top two overlap (164.3–172.5 vs 163.6–171.3), so treat the gap as small. On individual benchmarks: GPQA Diamond — Claude Sonnet 5.5 95.6%, GPT-6.1 Sol 95.4%, GLM-5.3 90.9%; FrontierMath Tiers 1–3 — GPT-6.1 Sol 93.7%, Claude Sonnet 5.5 88.8%, GLM-5.3 68.8%; OTIS Mock AIME 2024–2025 — GPT-6.1 Sol 100%, Claude Sonnet 5.5 100%, GLM-5.3 91.1%; SimpleQA Verified — GPT-6.1 Sol 73.9%, Claude Sonnet 5.5 46.5%, GLM-5.3 41.0%.
Which is better for coding?
There are no published SWE-bench Verified results for GPT-6.1 Sol, GLM-5.3 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 GLM-5.3 and 1,000,000 for Claude Sonnet 5.5. Maximum output per response: GPT-6.1 Sol up to 128,000, GLM-5.3 up to 131,072, Claude Sonnet 5.5 up to 128,000 tokens.
Which can read images, PDFs, audio or video?
GPT-6.1 Sol accepts text, images and PDFs; GLM-5.3 accepts text; 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?
GLM-5.3 publishes its weights and can be self-hosted; GPT-6.1 Sol and Claude Sonnet 5.5 is proprietary.
Which is newer?
GPT-6.1 Sol is the newest, released Sep 29, 2026. Claude Sonnet 5.5 came out Sep 28, 2026; GLM-5.3 came out Aug 14, 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 Nov 2, 2026.
