GLM-5.3 vs Claude Fable 5.1
Claude Fable 5.1 comes out ahead, 66 to 63 on our weighted score, though GLM-5.3 is 9.3× cheaper per token.
Z.ai (Zhipu)GLM-5.3
63/100- ECI156.2
- Price$1.40 / $4.40
- Context1M
- Our pick
AnthropicClaude Fable 5.1
66/100- ECI166.4
- Price$10.00 / $50.00
- Context1M
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Make it a three-way comparison.
Claude Fable 5.1 is our pick
Claude Fable 5.1 is the better all-round choice, scoring 66/100 against GLM-5.3 (63). It leads on capability and inputs & features. GLM-5.3 wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
- CapabilityClaude Fable 5.1Capabilities Index (ECI): Claude Fable 5.1 166.4 · GLM-5.3 156.2
- Lowest priceGLM-5.3GLM-5.3 $2.15 · Claude Fable 5.1 $20.00 per 1M tokens (3:1 blend)
- Longest contextAbout the sameGLM-5.3 1,000,000 · Claude Fable 5.1 1,000,000 tokens
- Widest inputsClaude Fable 5.1GLM-5.3: Text · Claude Fable 5.1: Text, Images, PDFs
- Self-hostingGLM-5.3Publishes downloadable weights
| Measure | Weight | GLM-5.3 | Claude Fable 5.1 |
|---|---|---|---|
| CapabilityCapabilities Index (ECI) | 50% | 84 | 97 |
| Price | 25% | 33 | 0 |
| Inputs & features | 15% | 45 | 80 |
| Context window | 10% | 60 | 60 |
| Overall | 100% | 63/100 | 66/100 |
Every spec in one table
Highlighted cells lead their row. Dashes mean the data is not published.
| Specification | GLM-5.3Z.ai (Zhipu) | Claude Fable 5.1Anthropic |
|---|---|---|
| Capability | ||
| Capabilities Index (ECI) | 156.2 | 166.4 (best) |
| ECI rank | #33 of 165 | #6 of 165 (best) |
| GPQA DiamondGraduate-level science questions | 90.9% | — |
| FrontierMath Tiers 1–3Research-level mathematics | 68.8% | 90.2% (best) |
| OTIS Mock AIME 2024–2025Competition mathematics | 91.1% | 100% (best) |
| SimpleQA VerifiedShort factual questions | 41.0% | 70.8% (best) |
| Price per million tokens | ||
| Input | $1.40 (best) | $10.00 |
| Output | $4.40 (best) | $50.00 |
| Cached input | $0.26 | $0.25 (best) |
| Blended (3:1) | $2.15 (best) | $20.00 |
| Long-context rate | Same rate | Same rate |
| Price source | Official Z.AI API | Official Anthropic API |
| Limits | ||
| Context window | 1,000,000 tokens | 1,000,000 tokens |
| Max output | 131,072 tokens (best) | 128,000 tokens |
| Inputs and features | ||
| Text | Yes | Yes |
| Images | No | Yes |
| PDFs | No | Yes |
| Audio | No | No |
| Video | No | No |
| Reasoning | Yeslow · high · max | Yeslow · medium · high · xhigh · max |
| Tool calling | Yes | Yes |
| Structured output | Yes | Yes |
| Availability | ||
| Weights | Open | Proprietary |
| API model ID | glm-5.3 | claude-fable-5-1 |
| API providers | 83 (best) | 37 |
| Released | Aug 14, 2026 | Sep 1, 2026 |
| Knowledge cutoff | — | 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.
- GLM-5.3$22.80
- Claude Fable 5.1$200.00
Which should you choose?
Which is better: GLM-5.3 or Claude Fable 5.1?
Claude Fable 5.1 is the better all-round choice, scoring 66/100 against GLM-5.3 (63). It leads on capability and inputs & features. GLM-5.3 wins on price. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.
Which is cheaper, GLM-5.3 or Claude Fable 5.1?
GLM-5.3 is cheaper at $1.40 input / $4.40 output per million tokens (official Z.AI API price). Claude Fable 5.1 costs $10.00 input / $50.00 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 $20.00 for Claude Fable 5.1 (9.3× as much).
Which scores higher on benchmarks?
Claude Fable 5.1 scores higher on the Capabilities Index (ECI): Claude Fable 5.1 166.4 (#6 of 165) and GLM-5.3 156.2 (#33 of 165). Their confidence ranges do not overlap (163.6–170.8 vs 154.3–158.5), so the gap is a real one. On individual benchmarks: FrontierMath Tiers 1–3 — Claude Fable 5.1 90.2%, GLM-5.3 68.8%; OTIS Mock AIME 2024–2025 — Claude Fable 5.1 100%, GLM-5.3 91.1%; SimpleQA Verified — Claude Fable 5.1 70.8%, GLM-5.3 41.0%.
Which is better for coding?
There are no published SWE-bench Verified results for GLM-5.3 and Claude Fable 5.1 yet, so there is no like-for-like coding score. On overall capability, Claude Fable 5.1 leads, which tends to carry over to coding, but test on your own codebase. Both support tool calling for agent workflows.
Which has the bigger context window?
GLM-5.3 and Claude Fable 5.1 share the same 1,000,000-token context window. Maximum output per response: GLM-5.3 up to 131,072, Claude Fable 5.1 up to 128,000 tokens.
Which can read images, PDFs, audio or video?
GLM-5.3 accepts text; Claude Fable 5.1 accepts text, images and PDFs. Claude Fable 5.1 handles the widest range of inputs.
Are any of these open source?
GLM-5.3 publishes its weights and can be self-hosted; Claude Fable 5.1 is proprietary.
Which is newer?
Claude Fable 5.1 is the newest, released Sep 1, 2026. GLM-5.3 came out Aug 14, 2026. Knowledge cutoff: Claude Fable 5.1 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.
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