GLM-5.1 vs Claude Opus 4.1
GLM-5.1 comes out ahead, 57 to 49 on our weighted score, and it is the cheaper option too.
- Our pick
Z.ai (Zhipu)GLM-5.1
57/100- ECI149.9
- Price$1.40 / $4.40
- Context200K
AnthropicClaude Opus 4.1
49/100- ECI144.1
- Price$15.00 / $75.00
- Context200K
Add a model
Make it a three-way comparison.
GLM-5.1 is our pick
GLM-5.1 is the better all-round choice, scoring 57/100 against Claude Opus 4.1 (49). It leads on capability and price. Claude Opus 4.1 wins on inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityGLM-5.1Capabilities Index (ECI): GLM-5.1 149.9 · Claude Opus 4.1 144.1
- Lowest priceGLM-5.1GLM-5.1 $2.15 · Claude Opus 4.1 $30.00 per 1M tokens (3:1 blend)
- Longest contextAbout the sameGLM-5.1 200,000 · Claude Opus 4.1 200,000 tokens
- Widest inputsClaude Opus 4.1GLM-5.1: Text · Claude Opus 4.1: Text, Images, PDFs
- Self-hostingGLM-5.1Publishes downloadable weights
| Measure | Weight | GLM-5.1 | Claude Opus 4.1 |
|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 78 | 71 |
| Price | 25% | 34 | 0 |
| Inputs & features | 15% | 45 | 70 |
| Context window | 10% | 32 | 32 |
| Overall | 100% | 57/100 | 49/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GLM-5.1Z.ai (Zhipu) | Claude Opus 4.1Anthropic |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | 149.9 (best) | 144.1 |
| ECI rank | #51 of 148 (best) | #81 of 148 |
| GPQA DiamondGraduate-level science questions | 89.9% (best) | 77.3% |
| FrontierMath Tiers 1–3Research-level mathematics | 36.8% (best) | 12.6% |
| OTIS Mock AIME 2024–2025Competition mathematics | 93.3% (best) | 68.9% |
| SWE-bench VerifiedFixing real GitHub issues | 74.2% (best) | 73.4% |
| SimpleQA VerifiedShort factual questions | 34.0% | — |
| Price per million tokens | ||
| Input | $1.40 (best) | $15.00 |
| Output | $4.40 (best) | $75.00 |
| Cached input | $0.26 | — |
| Blended (3:1) | $2.15 (best) | $30.00 |
| Long-context rate | Same rate | Same rate |
| Price source | Official Z.AI API | Median of 14 providers |
| Limits | ||
| Context window | 200,000 tokens | 200,000 tokens |
| Max output | 131,072 tokens (best) | 32,000 tokens |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | No | Yes |
| PDFs | No | Yes |
| Audio | No | No |
| Video | No | No |
| Reasoning | Yes | Yes |
| Tool calling | Yes | Yes |
| Structured output | Yes | No |
| Availability | ||
| Weights | Open | Proprietary |
| API model ID | glm-5.1 | — |
| API providers | 40 (best) | 14 |
| Released | Apr 7, 2026 | Aug 5, 2025 |
| Knowledge cutoff | — | Mar 31, 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
- Claude Opus 4.1$300.00
Which should you choose?
Which is better: GLM-5.1 or Claude Opus 4.1?
GLM-5.1 is the better all-round choice, scoring 57/100 against Claude Opus 4.1 (49). It leads on capability and price. Claude Opus 4.1 wins on inputs & features. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, GLM-5.1 or Claude Opus 4.1?
GLM-5.1 is cheaper at $1.40 input / $4.40 output per million tokens (official Z.AI API price). Claude Opus 4.1 costs $15.00 input / $75.00 output per million tokens (median across 14 API providers). At a typical mix of three input tokens to one output token, that is $2.15 per million tokens for GLM-5.1 versus $30.00 for Claude Opus 4.1 (14× as much).
Which scores higher on benchmarks?
GLM-5.1 scores higher on the Capabilities Index (ECI): GLM-5.1 149.9 (#51 of 148) and Claude Opus 4.1 144.1 (#81 of 148). Their confidence ranges do not overlap (148.0–151.6 vs 141.6–146.0), so the gap is a real one. On individual benchmarks: GPQA Diamond — GLM-5.1 89.9%, Claude Opus 4.1 77.3%; FrontierMath Tiers 1–3 — GLM-5.1 36.8%, Claude Opus 4.1 12.6%; OTIS Mock AIME 2024–2025 — GLM-5.1 93.3%, Claude Opus 4.1 68.9%; SWE-bench Verified — GLM-5.1 74.2%, Claude Opus 4.1 73.4%.
Which is better for coding?
GLM-5.1 resolves more real GitHub issues on SWE-bench Verified: GLM-5.1 74.2% and Claude Opus 4.1 73.4%. Both support tool calling for agent workflows.
Which has the bigger context window?
GLM-5.1 and Claude Opus 4.1 share the same 200,000-token context window. Maximum output per response: GLM-5.1 up to 131,072, Claude Opus 4.1 up to 32,000 tokens.
Which can read images, PDFs, audio or video?
GLM-5.1 accepts text; Claude Opus 4.1 accepts text, images and PDFs. Claude Opus 4.1 handles the widest range of inputs.
Are any of these open source?
GLM-5.1 publishes its weights and can be self-hosted; Claude Opus 4.1 is proprietary.
Which is newer?
GLM-5.1 is the newest, released Apr 7, 2026. Claude Opus 4.1 came out Aug 5, 2025. Knowledge cutoff: Claude Opus 4.1 Mar 31, 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.
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