GLM-5.1 vs GPT-5.1 vs Claude Opus 4.5
Too close to call on our weighted score (GPT-5.1 60, GLM-5.1 57, Claude Opus 4.5 55). The right pick depends on what you value most.
Z.ai (Zhipu)GLM-5.1
57/100- ECI149.9
- Price$1.40 / $4.40
- Context200K
OpenAIGPT-5.1
60/100- ECI149.7
- Price$1.25 / $10.00
- Context400K
AnthropicClaude Opus 4.5
55/100- ECI150.1
- Price$5.00 / $25.00
- Context200K
Too close to call
It is close. Our weighted score puts them within 2 points (GPT-5.1 60/100, GLM-5.1 57/100, Claude Opus 4.5 55/100), so choose by what matters most for your work: Claude Opus 4.5 for raw capability, GLM-5.1 on price and GPT-5.1 for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityClaude Opus 4.5Capabilities Index (ECI): Claude Opus 4.5 150.1 · GLM-5.1 149.9 · GPT-5.1 149.7
- Lowest priceGLM-5.1GLM-5.1 $2.15 · GPT-5.1 $3.44 · Claude Opus 4.5 $10.00 per 1M tokens (3:1 blend)
- Longest contextGPT-5.1GPT-5.1 400,000 · GLM-5.1 200,000 · Claude Opus 4.5 200,000 tokens
- Widest inputsClaude Opus 4.5GLM-5.1: Text · GPT-5.1: Text, Images · Claude Opus 4.5: Text, Images, PDFs
- Self-hostingGLM-5.1Publishes downloadable weights
| Measure | Weight | GLM-5.1 | GPT-5.1 | Claude Opus 4.5 |
|---|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 78 | 78 | 78 |
| Price | 25% | 34 | 24 | 2 |
| Inputs & features | 15% | 45 | 70 | 80 |
| Context window | 10% | 32 | 44 | 32 |
| Overall | 100% | 57/100 | 60/100 | 55/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GLM-5.1Z.ai (Zhipu) | GPT-5.1OpenAI | Claude Opus 4.5Anthropic |
|---|---|---|---|
| Capability | |||
| Capabilities Index (ECI) | 149.9 | 149.7 | 150.1 (best) |
| ECI rank | #51 of 148 | #52 of 148 | #48 of 148 (best) |
| GPQA DiamondGraduate-level science questions | 89.9% (best) | 87.6% | 86.1% |
| FrontierMath Tiers 1–3Research-level mathematics | 36.8% (best) | — | 34.4% |
| OTIS Mock AIME 2024–2025Competition mathematics | 93.3% (best) | 88.6% | 86.1% |
| SWE-bench VerifiedFixing real GitHub issues | 74.2% | 68.0% | 76.7% (best) |
| SimpleQA VerifiedShort factual questions | 34.0% | 48.0% (best) | 45.7% |
| Price per million tokens | |||
| Input | $1.40 | $1.25 (best) | $5.00 |
| Output | $4.40 (best) | $10.00 | $25.00 |
| Cached input | $0.26 | $0.125 (best) | $0.50 |
| Blended (3:1) | $2.15 (best) | $3.44 | $10.00 |
| Long-context rate | Same rate | Same rate | Same rate |
| Price source | Official Z.AI API | Official OpenAI API | Official Anthropic API |
| Limits | |||
| Context window | 200,000 tokens | 400,000 tokens (best) | 200,000 tokens |
| Max output | 131,072 tokens (best) | 128,000 tokens | 64,000 tokens |
| Inputs and features | |||
| Text | Yes | Yes | Yes |
| Images | No | Yes | Yes |
| PDFs | No | No | Yes |
| Audio | No | No | No |
| Video | No | No | No |
| Reasoning | Yes | Yeslow · medium · high | Yeslow · medium · high |
| Tool calling | Yes | Yes | Yes |
| Structured output | Yes | Yes | Yes |
| Availability | |||
| Weights | Open | Proprietary | Proprietary |
| API model ID | glm-5.1 | gpt-5.1 | claude-opus-4-5 |
| API providers | 40 (best) | 21 | 28 |
| Released | Apr 7, 2026 | Nov 13, 2025 | Nov 24, 2025 |
| Knowledge cutoff | — | Sep 30, 2024 | May 2025 |
What would a month cost?
Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.
- GLM-5.1$22.80
- GPT-5.1$32.50
- Claude Opus 4.5$100.00
Which should you choose?
Which is better: GLM-5.1, GPT-5.1 or Claude Opus 4.5?
It is close. Our weighted score puts them within 2 points (GPT-5.1 60/100, GLM-5.1 57/100, Claude Opus 4.5 55/100), so choose by what matters most for your work: Claude Opus 4.5 for raw capability, GLM-5.1 on price and GPT-5.1 for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, GLM-5.1, GPT-5.1 or Claude Opus 4.5?
GLM-5.1 is cheaper at $1.40 input / $4.40 output per million tokens (official Z.AI API price). GPT-5.1 costs $1.25 input / $10.00 output per million tokens (official OpenAI API price); Claude Opus 4.5 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 $2.15 per million tokens for GLM-5.1 versus $3.44 for GPT-5.1 (1.6× as much) and $10.00 for Claude Opus 4.5 (4.7× as much).
Which scores higher on benchmarks?
Claude Opus 4.5 scores higher on the Capabilities Index (ECI): Claude Opus 4.5 150.1 (#48 of 148), GLM-5.1 149.9 (#51 of 148) and GPT-5.1 149.7 (#52 of 148). The confidence ranges of the top two overlap (147.9–153.0 vs 148.0–151.6), so treat the gap as small. On individual benchmarks: GPQA Diamond — GLM-5.1 89.9%, GPT-5.1 87.6%, Claude Opus 4.5 86.1%; OTIS Mock AIME 2024–2025 — GLM-5.1 93.3%, GPT-5.1 88.6%, Claude Opus 4.5 86.1%; SWE-bench Verified — Claude Opus 4.5 76.7%, GLM-5.1 74.2%, GPT-5.1 68.0%; SimpleQA Verified — GPT-5.1 48.0%, Claude Opus 4.5 45.7%, GLM-5.1 34.0%.
Which is better for coding?
Claude Opus 4.5 resolves more real GitHub issues on SWE-bench Verified: Claude Opus 4.5 76.7%, GLM-5.1 74.2% and GPT-5.1 68.0%. All three support tool calling for agent workflows.
Which has the bigger context window?
GPT-5.1 has the largest context window at 400,000 tokens, against 200,000 for GLM-5.1 and 200,000 for Claude Opus 4.5. Maximum output per response: GLM-5.1 up to 131,072, GPT-5.1 up to 128,000, Claude Opus 4.5 up to 64,000 tokens.
Which can read images, PDFs, audio or video?
GLM-5.1 accepts text; GPT-5.1 accepts text and images; Claude Opus 4.5 accepts text, images and PDFs. Claude Opus 4.5 handles the widest range of inputs.
Are any of these open source?
GLM-5.1 publishes its weights and can be self-hosted; GPT-5.1 and Claude Opus 4.5 is proprietary.
Which is newer?
GLM-5.1 is the newest, released Apr 7, 2026. Claude Opus 4.5 came out Nov 24, 2025; GPT-5.1 came out Nov 13, 2025. Knowledge cutoff: GPT-5.1 Sep 30, 2024, Claude Opus 4.5 May 2025.
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.
