Claude Fable 5.1 wins on coding (100 vs 91) and writing quality. GLM-5.3 wins on price ($1.4 vs $10/1M input). For most workflows, Claude Fable 5.1 is the stronger default — new frontier leader — better than fable 5 on every published benchmark, and cheaper to run.
The shortest way to see the safest default, the lower-cost option, and the specialist pick before you read deeper.
Claude Fable 5.1 is the safest overall answer here when you want the strongest default instead of the lowest list price.
Grok 4.5 is the lower-cost option to start with when you still need useful output at scale.
GLM-5.3 is the better pick when response speed matters more than maximum reasoning depth.
Claude Fable 5.1 leads on coding with a score of 100 vs 91 for GLM-5.3.
GLM-5.3 is cheaper at $1.4/1M input tokens vs $10/1M for Claude Fable 5.1.
Claude Fable 5.1 is the stronger default for coding tasks.
Claude Fable 5.1 is the safer default: it is built for frontier agentic coding, long-horizon autonomous work, and agentic scientific research, which covers most of what people bring to this comparison.
GLM-5.3 earns its place when your work is mostly agentic engineering and security work on open weights, even though it loses the overall count here.
GLM-5.3 is the more cost-efficient option at $1.4/1M input — Claude Fable 5.1 costs 7x more per input token, so the gap is worth taking seriously wherever token volume rather than peak quality drives the bill.
Switch the scoring lens to see whether the top answer changes when you care more about cost, speed, or long-document work.
Anthropic / Premium / Sep 1, 2026
New frontier leader — better than Fable 5 on every published benchmark, and cheaper to run.
Ranks models by the broadest mix of coding, writing, research, and long-context usefulness.
You need low latency, or your workload is uncached and cost-sensitive — Claude Opus 5 is half the base price and within a few points on agentic coding.
The fastest way to see where the recommendation shifts when your priority changes.
New frontier leader — better than Fable 5 on every published benchmark, and cheaper to run.
Same price as GLM-5.2, far stronger on agents and security.
Every figure below is the provider's list price or a published capability score — the same numbers the recommendation on this page is built from.
| Model | Input | Output | Est. month | Context | Speed | Coding | Writing | Research |
|---|---|---|---|---|---|---|---|---|
| Claude Fable 5.1Anthropic | $10.00/1M | $50.00/1M | $200 | 1M tokens | Deliberate | 100 | 98 | 100 |
| GLM-5.3Z.ai | $1.40/1M | $4.40/1M | $23 | 1M tokens | Balanced | 91 | 79 | 82 |
Capability scores are out of 100 and reflect our own weighting of published benchmarks and production signals — see how we evaluate models. “Est. month” assumes 10M input and 2M output tokens at list price, with no batch or caching discounts applied, so treat it as a ceiling.
What each one is genuinely good at, where it falls down, and the situations we would steer you away from it — not just the headline score.
Anthropic's September 1, 2026 frontier release and the new capability ceiling for coding, agents, and scientific work. Base pricing is unchanged at $10/$50, but cache reads dropped 75% to $0.25/1M — roughly 25% cheaper on typical workloads and up to 45% cheaper on agentic ones. 1M context, 128K output, adaptive thinking always on.
You need low latency, or your workload is uncached and cost-sensitive — Claude Opus 5 is half the base price and within a few points on agentic coding.
The new frontier leader, and the rare upgrade that costs less than the model it replaces. Base $10/$50 pricing did not move, but a 75% cut to cache reads makes typical workloads ~25% cheaper than Fable 5 and heavily agentic ones ~45% cheaper — while more than doubling Fable 5 on agentic science and beating Opus 5 on agentic coding. If you were already on Fable 5, switching is a straight win. If you were on Opus 5 for the price, it still costs 2x on uncached tokens.
Released September 1, 2026 alongside Claude Mythos 5.1, the first update to the Mythos-class line since Fable 5 on June 9. API ID claude-fable-5-1; generally available on the Claude API, Amazon Bedrock, Google Cloud, and Microsoft Foundry. Published launch numbers (Fable 5.1 / Fable 5 / Opus 5 / GPT-5.6 Sol): Terminal-Bench-Science 0.1 52.6 / 24.7 / 29.0 / 22.4; Terminal-Bench 4.0 55.8 / 42.0 / 52.3 / 37.3; CursorBench 3.2.0 73.4 / 70.5 / 70.0 / 67.2; AutomationBench 31.4 / 17.1 / 26.9 / 19.6; OSWorld 2.0 strict 41.7 / 36.1 / 39.6; Humanity's Last Exam (no tools) 60.9 / 57.8 / 56.6; GDPval-AA v2 1853 / 1723 / 1824 / 1711. GDPval-AA v2 is rescaled from the v1 numbers quoted on the Fable 5 page and is not directly comparable to them.
Z.ai's newest flagship, aimed squarely at software engineering, autonomous agents and cybersecurity — and the first open-weights model to beat Claude Mythos 5 on a security benchmark.
Your procurement process requires a SWE-bench Verified figure, or you need the closed-frontier reasoning ceiling.
The clear upgrade over GLM-5.2 at the same price — take it unless you specifically need a published SWE-bench Verified number to sign off on. The security benchmark lead over Mythos 5 is the genuinely new thing here.
Released August 14, 2026. Z.ai list pricing is $1.40/$4.40, the same rate as GLM-5.2; resellers discount from that list. Also available through the GLM Coding Plan from $18/mo. Reported GPQA Diamond 91.7% and Artificial Analysis Intelligence Index 59.5.
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Claude Fable 5.1 wins on more of the categories we score — coding, research, long context — so it is the better default of the two. GLM-5.3 is the better pick when your work is mostly agentic engineering and security work on open weights. Neither is universally "better": Claude Fable 5.1 is aimed at frontier agentic coding and long-horizon autonomous work, GLM-5.3 at agentic engineering and security work on open weights.
GLM-5.3 is cheaper at $1.4/1M input and $4.4/1M output. Claude Fable 5.1 costs $10/1M input and $50/1M output.
Both Claude Fable 5.1 and GLM-5.3 have the same 1M context window.
Claude Fable 5.1 is better for coding with a score of 100 vs GLM-5.3's 91 (out of 100). Claude Fable 5.1 is the overall coding leader in this directory at 100/100.
GLM-5.3 is faster with a balanced speed rating (score: 3) vs Claude Fable 5.1's deliberate rating (score: 2). Speed matters most for interactive and high-throughput work; for batch jobs the Claude Fable 5.1 latency penalty is usually invisible.
Base rates are still $10/$50 per 1M — double Claude Opus 5 for anything that is not cache-heavy. Anthropic published no SWE-bench Verified or SWE-bench Pro figure for 5.1 at launch. On Claude Pro it only runs on pay-as-you-go credits; Max includes it up to 50% of weekly limits. Avoid it if you need low latency, or your workload is uncached and cost-sensitive — Claude Opus 5 is half the base price and within a few points on agentic coding. That is the main case for looking at GLM-5.3 instead.
No published SWE-bench Verified score, so it is absent from the benchmark most buyers compare on. Priced identically to GLM-5.2 at $1.40/$4.40 — the upgrade is capability, not value. Avoid it if your procurement process requires a SWE-bench Verified figure, or you need the closed-frontier reasoning ceiling. Against Claude Fable 5.1 specifically, the gap shows up most on coding (100 vs 91).
Take a moderate workload of 10M input and 2M output tokens a month. Claude Fable 5.1 runs $200.00 (at $10/1M in and $50/1M out); GLM-5.3 runs $22.80 (at $1.4/1M in and $4.4/1M out). That is a $177.20/month difference — GLM-5.3 is the cheaper of the two at this volume, and the gap scales linearly as you send more. Output tokens dominate the bill on both, so prompt length matters far less than response length.
Yes, and for most teams that beats picking one. A common split is Claude Fable 5.1 for frontier agentic coding and long-horizon autonomous work, with GLM-5.3 handling agentic engineering and security work on open weights. Routing high-volume, low-stakes calls to GLM-5.3 at $1.4/1M and reserving Claude Fable 5.1 for the hard cases is usually the cheapest arrangement that does not cost you quality.