Prices verified 2026-09-02; GLM 5.3 figures as of September 2026
Fable 5.1 pricing is from Anthropic's September 2 release. GLM 5.3 rates are Zhipu list prices as of September 2026.
Browse all Chinese model comparisonsFable 5.1 vs GLM 5.3 · September 2026
Claude Fable 5.1 vs GLM 5.3
Anthropic's latest flagship against Zhipu's 2M-context open-weights challenger — specs, benchmarks, price, and when each model is the right call.
TL;DR
Fable 5.1 leads on agentic coding (87.7% SWE-bench Verified) and complex reasoning. GLM 5.3 wins on price (~8x cheaper input), 2M context, and self-hosting with open weights.
Specs at a glance
Fable 5.1 prices are Anthropic list rates; GLM 5.3 rates are Zhipu figures as of September 2026.
| Spec | Claude Fable 5.1 | GLM 5.3 |
|---|---|---|
| Model ID | claude-fable-5-1-20260902 | GLM-5.3 |
| Input price (per M tokens) | $10.00 | $1.20 |
| Output price (per M tokens) | $50.00 | $3.60 |
| Prompt cache read (per M tokens) | $1.00 | $0.30 |
| Context window | 1M | 2M |
| Max output | 128K | 64K |
| License | Closed API (proprietary) | Open weights — MIT |
| Data retention | 30-day mandatory | None (self-hostable) |
| Extended thinking | Adaptive budget + effort tiers | Standard reasoning tiers |
Fable 5.1 carries mandatory 30-day retention; GLM 5.3 is open-weights (MIT) and can be self-hosted.
Benchmark comparison
Fable 5.1 leads on coding and reasoning; GLM 5.3's 2M context is unmatched for whole-repo ingestion.
| Spec | Claude Fable 5.1 | GLM 5.3 |
|---|---|---|
| SWE-bench Verified | 87.7% | 68.4% |
| FrontierMath | 38.2% | 24.1% |
| Humanity's Last Exam (HLE) | 61.4% | 42.8% |
| OSWorld | 89.6% | 64.5% |
| Needle-in-haystack (context) | 99.8% (1M) | 98.2% (2M) |
| Time to first token | Low (optimized streaming) | Fast (regional edge) |
Fable 5.1 from Anthropic September 2, 2026 release. GLM 5.3 SWE-bench 68.4% vendor-reported by Zhipu.
How to decide
Route by what you actually need, not by the headline.
You need 2M-token whole-repo analysis
GLM 5.3's 2M context lets you ingest an entire monorepo in one shot. Fable 5.1's 1M window requires chunking for the largest codebases.
You're cost-sensitive at scale
At $1.20/$3.60 vs $10/$50, GLM 5.3 is roughly 8x cheaper on input. For high-volume batch work, GLM 5.3 wins on cost.
You need frontier agentic coding
Fable 5.1's 87.7% SWE-bench and 38.2% FrontierMath are a tier above GLM 5.3's 68.4% and 24.1%.
You need to self-host or air-gap
GLM 5.3's MIT open weights let you run locally or fine-tune. Fable 5.1 is a closed API only.
Retention or data sovereignty matters
Fable 5.1's 30-day mandatory retention is a blocker for some teams. GLM 5.3 self-hosted gives full data control.
The ~8x input price gap narrows when you factor in failed attempts on hard agentic tasks.
Estimate the real cost
Run both models through your own token mix before you commit to a production route.