Claude Opus 5 vs Claude Fable 5: Which Should You Use?
Model Comparison
Claude Fable 5 is Anthropic’s most capable model. Claude Opus 5 is the one Anthropic tells you to start with. At $10/$50 versus $5/$25 per million tokens, the real question isn’t which is stronger — it’s whether the gap is worth double the price for your work.
Disclosure and fact-check: this comparison was originally written by Claude Opus 5 — one of the two models being compared. That’s an obvious conflict of interest, so ClaudeAIHub.com sent a second, independent reviewer: Claude Sonnet 5 fact-checked every claim below against Anthropic’s official documentation and independent reporting on August 6, 2026. That review corrected three things — a tokenizer claim that unfairly singled out Fable 5 (both models actually use the same one), three benchmark rows that implied a head-to-head with Fable 5 when no such comparison was ever published, and a genuine Fable 5 win (legal and health tasks) the original draft missed. What’s below is Anthropic’s own published data, checked twice.
Quick answer: Choose Claude Opus 5 for agentic coding, computer use, and cost-sensitive work — it leads on OSWorld 2.0, Frontier-Bench v0.1, and GDPval-AA v2 knowledge work, at half Fable 5’s price. Choose Claude Fable 5 only where it still wins: CursorBench 3.2 (by 0.5%) and legal/health-heavy tasks. Most people need neither — Claude Sonnet 5 is cheaper than both and enough for everyday work.
Opus 5 vs Fable 5 at a Glance
| Dimension | Claude Opus 5 | Claude Fable 5 |
|---|---|---|
| Launched | July 24, 2026 | June 9, 2026 |
| API model ID | claude-opus-5 | claude-fable-5 |
| Positioning | Recommended default for complex agentic coding & enterprise work | Most capable widely released model; next-generation intelligence for long-running agents |
| Standard pricing | $5 / $25 per MTok | $10 / $50 per MTok |
| Batch API pricing | $2.50 / $12.50 per MTok | $5 / $25 per MTok |
| Prompt cache reads | $0.50 / MTok | $1 / MTok |
| Speed option | Fast mode (research preview): ~2.5× speed at $10/$50 | — |
| Context / max output | 1M / 128k tokens | 1M / 128k tokens |
| Knowledge cutoff | May 2026 | January 2026 |
| Latency | Moderate | Slower |
| Thinking | Adaptive (effort defaults to high) | Adaptive, always on |
| Data retention | None for general access | 30-day retention on Mythos-class traffic |
| Safeguard behaviour | Cyber classifiers fire ~85% less often; flagged requests fall back to Opus 4.8 | Classifiers route some requests to Opus 4.8 (under 5% of sessions) |
Both models use the same tokenizer (introduced with Opus 4.7), so token-count differences between them are not a factor — see the cost section below.
What the Benchmarks Actually Say
Anthropic’s framing of Opus 5 is that it “comes close to the frontier intelligence of Claude Fable 5 at half the price.” On the benchmarks where both models have been directly measured against each other, that holds up — but not every number Anthropic published for Opus 5 has a matching Fable 5 score to compare it to, and it’s important not to blur that distinction:
| Benchmark | Opus 5 | Fable 5 | Verdict |
|---|---|---|---|
| CursorBench 3.2 (agentic coding, max effort) | Opus 5 lands within 0.5% of Fable 5’s peak score, at half the cost per task | Fable 5, barely | |
| OSWorld 2.0 (computer use) | Opus 5 surpasses Fable 5’s best result, at just over a third of the cost | Opus 5 | |
| Frontier-Bench v0.1 (agentic coding) | 43.3% | 33.7% | Opus 5 |
| GDPval-AA v2 (real-world knowledge work, Elo) | 1,861 | 1,747 | Opus 5 |
| ARC-AGI 3 (novel problem-solving) | 30.2% | not tested | No Fable 5 comparison exists |
| Zapier AutomationBench (workflow automation) | ~1.5× the next-best competing model | no published score | No Fable 5 comparison exists |
| Legal- and health-domain tasks | — | Reported edge, by a small margin | Fable 5 |
Two takeaways. First, on the benchmarks where Anthropic and independent testing both put a number on each model, Opus 5 wins three of four (Frontier-Bench v0.1, OSWorld 2.0, GDPval-AA v2) and Fable 5 wins one, narrowly (CursorBench 3.2). Second, Anthropic’s ARC-AGI 3 and Zapier AutomationBench figures for Opus 5 are real, but they compare it to “the next-best model” generally — not specifically to Fable 5, which was never benchmarked on ARC-AGI 3 at all. Treat those two as evidence of Opus 5’s strength in absolute terms, not as confirmed wins over Fable 5 specifically.
For the wider lineup, see Claude Models Explained.
The Real Cost Difference
Per-token, Fable 5 costs exactly double on standard pricing. The practical gap moves around that baseline for a few reasons:
- Fable 5 is slower. Anthropic lists its comparative latency as “Slower” against Opus 5’s “Moderate.” On long agentic runs, wall-clock time is a cost too.
- Opus 5 has a cheaper speed lever. If you need Fable-class turnaround, Opus 5’s fast mode (currently a research preview) costs $10/$50 — the same as Fable 5’s standard rate — while running about 2.5× its base speed.
- Opus 5’s Batch and caching rates are also half of Fable 5’s — $2.50/$12.50 vs $5/$25 for Batch API, $0.50 vs $1 per MTok for cache reads. The 2× gap holds across pricing modes, it isn’t just the headline rate.
One thing that does not widen the gap, despite an earlier version of this article claiming otherwise: both models use the same tokenizer (introduced with Opus 4.7), which produces roughly 30% more tokens than pre-4.7 models for the same text. That affects your budget versus older models — it does not favor either Opus 5 or Fable 5 over the other. Model your own numbers with the Claude API cost estimator, which includes both models and Opus 5’s fast mode.
Access, Plans, and Restrictions
This is where the two diverge most sharply, and it catches people out:
- Opus 5 is the default model on Claude Max and the strongest model on Pro. It has no data-retention requirement for general access, and it’s available across the API, claude.ai, Claude Code, and Claude Cowork.
- Fable 5 is included in Max and Team Premium plans at up to 50% of weekly limits. On Pro and Team Standard it requires usage credits billed at API rates — Anthropic granted those users a one-time $100 credit when the arrangement began. Mythos-class traffic also carries a 30-day data-retention requirement, which can matter for compliance-sensitive work.
On safeguards, both route flagged requests to Opus 4.8, but at very different rates: Fable 5’s classifiers trigger in under 5% of sessions, while Anthropic expects cyber classifiers to intervene around 85% less often for Opus 5 than for Fable 5. If you work in security-adjacent domains and have found Fable 5 frustratingly cautious, that difference is the reason. Full details on each: the Claude Opus 5 guide and the Claude Fable 5 guide.
The Verdict: Which Should You Use?
Choose Claude Opus 5 if you’re doing complex agentic coding, enterprise workloads, or computer-use automation. It’s Anthropic’s own recommended starting point, it has confirmed leads on OSWorld 2.0, Frontier-Bench v0.1, and GDPval-AA v2 knowledge-work benchmarks, it has the more current knowledge cutoff (May 2026 vs January 2026), it’s faster, it has no retention requirement, and it triggers far fewer false refusals. For most teams, this is the default.
Choose Claude Fable 5 if you need the absolute ceiling on capability and the half-percent at the top of CursorBench 3.2 is worth double the price, or your work is legal- or health-domain heavy, where independent testing reports Fable 5 holding a narrow edge. It also fits very long-horizon agentic runs where a single failure costs more than the token bill.
Honestly, for most people: neither. If your work is everyday writing, research, or routine coding, Claude Sonnet 5 at $3/$15 per MTok will do the job faster and cheaper than both, and the quality difference won’t be your bottleneck. Reach for a flagship when the task genuinely warrants it. The Claude model selector can sanity-check that decision in a few clicks.
Frequently Asked Questions
Is Claude Opus 5 better than Claude Fable 5?
On the benchmarks where both models have been directly measured, Opus 5 leads on three of four: Frontier-Bench v0.1 (43.3% vs 33.7%), OSWorld 2.0 computer use, and GDPval-AA v2 knowledge work. Fable 5 holds the top spot on CursorBench 3.2, though Opus 5 lands within 0.5% of it at half the price. Independent reporting also credits Fable 5 with a narrow edge on legal- and health-domain tasks. Anthropic recommends starting with Opus 5 and reserving Fable 5 for work that needs the absolute ceiling.
What is the price difference between Opus 5 and Fable 5?
Claude Opus 5 costs $5 per million input tokens and $25 per million output tokens. Claude Fable 5 costs $10 and $50 — exactly double. That 2x gap holds across pricing modes: Opus 5’s Batch API rate ($2.50/$12.50) and cache-read rate ($0.50/MTok) are also half of Fable 5’s ($5/$25 and $1/MTok).
Is Claude Fable 5 worth double the price of Opus 5?
For most workloads, no — Opus 5 comes within 0.5% of Fable 5 on CursorBench 3.2 and leads on computer use and real-world knowledge-work benchmarks. Fable 5 earns its price on very long-horizon agentic runs, research-grade work, and legal- or health-domain tasks where independent testing shows it holding a narrow edge.
Was Claude Fable 5 tested on ARC-AGI-3?
No. Anthropic published an ARC-AGI-3 score for Claude Opus 5 (30.2%) as a comparison against competing AI models, but Fable 5 was not tested on this benchmark, so there is no direct Opus-5-vs-Fable-5 comparison on it despite some early coverage implying otherwise.
Which is faster, Claude Opus 5 or Fable 5?
Opus 5. Anthropic lists Opus 5’s comparative latency as “Moderate” and Fable 5’s as “Slower.” Opus 5 also offers a fast mode (currently in research preview) that runs roughly 2.5 times its base speed for $10/$50 per MTok — the same rate as Fable 5’s standard pricing.
Are Opus 5 and Fable 5 both included in my Claude plan?
Opus 5 is the default model on Claude Max and the strongest model on Pro. Fable 5 is included in Max and Team Premium at up to 50% of weekly limits, but Pro and Team Standard users need usage credits to access it, billed at API rates.
Does Claude Fable 5 have data retention requirements?
Yes. Mythos-class traffic, which includes Fable 5, carries a 30-day data-retention requirement. Claude Opus 5 has no data-retention requirement for general access, which can matter for compliance-sensitive workloads.