Claude Fable 5 vs GPT-5.2
Anthropic · US | OpenAI · US · Updated June 2026
Quick verdict
Pick Claude Fable 5 for the hardest reasoning and most complex problems or long-horizon, multi-step agentic work. Pick GPT-5.2 for strong all-round reasoning or reliable structured output. On a tight budget at scale, GPT-5.2 is the value pick.
Claude Fable 5 (Anthropic) and GPT-5.2 (OpenAI) are two of the models people most often weigh against each other in 2026. Claude Fable 5 is anthropic's top public Mythos-class model and its most capable yet, though tier access was temporarily suspended in June 2026 under a US export-control directive. GPT-5.2 is a capable GPT-5-generation all-rounder, now succeeded by GPT-5.5. They diverge most on price and context window — each quantified below from the models' real specs.
Key differences at a glance
- ▸Price: GPT-5.2 is about 5.7× cheaper on input ($1.75/$14 per 1M tokens vs $10/$50 per 1M tokens) — a large enough gap that at scale it can be the single biggest line item in the decision.
- ▸Context window: Claude Fable 5 holds 2.5× more — 1M (~1,500 pages) vs 400K (~600 pages). But effective recall usually fades long before the advertised ceiling, so the bigger number only helps if the model reasons over it.
- ▸Recency: Claude Fable 5 is the newer model by about 6 months (released June 9, 2026), usually meaning fresher training data and capabilities.
Side-by-side specs
| Spec | Claude Fable 5 | GPT-5.2 |
|---|---|---|
| Provider | Anthropic (US) | OpenAI (US) |
| Released | June 9, 2026 | December 11, 2025 |
| Context window | 1M (~1,500 pages) | 400K (~600 pages) |
| Price (in/out) | $10/$50 per 1M tokens | $1.75/$14 per 1M tokens |
| Open weight? | No — API only | No — API only |
| Modalities | text, image, code | text, image, code |
| SWE-Bench Verified | Not published | Not published |
| MRCR v2 @ 1M | Not published | Not published |
Who wins what
The hardest reasoning and most complex problems
Claude Fable 5
Anthropic's top public Mythos-class model and its most capable yet, though tier access was temporarily suspended in June 2026 under a US export-control directive — and it carries the larger 1M context.
Long-horizon, multi-step agentic work
Claude Fable 5
Its 1M window holds about 2.5× more than GPT-5.2's 400K in a single prompt.
Frontier-level analysis and research
Claude Fable 5
Anthropic's top public Mythos-class model and its most capable yet, though tier access was temporarily suspended in June 2026 under a US export-control directive — and it is the newer of the two.
Strong all-round reasoning
GPT-5.2
A capable GPT-5-generation all-rounder, now succeeded by GPT-5.5 — and it runs cheaper at $1.75/$14 per 1M tokens.
Reliable structured output
GPT-5.2
GPT-5.2 lists reliable structured output among its strengths; Claude Fable 5 does not.
Broad ecosystem and tooling
GPT-5.2
GPT-5.2 lists broad ecosystem and tooling among its strengths; Claude Fable 5 does not.
Lowest cost at scale
GPT-5.2
At $1.75/$14 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.
Largest single-prompt input
Claude Fable 5
Its 1M window is about 2.5× larger than GPT-5.2's 400K, fitting roughly 1,500 pages in one prompt.
Which should you pick?
A cost-sensitive startup shipping high volume
→ GPT-5.2
At $1.75/$14 per 1M tokens it undercuts Claude Fable 5, and on millions of tokens that margin decides the monthly bill.
Someone analysing very long documents or codebases
→ Claude Fable 5
Larger 1M window fits more in one prompt.
Anyone whose priority is the hardest reasoning and most complex problems
→ Claude Fable 5
It is specifically built for that.
Anyone whose priority is strong all-round reasoning
→ GPT-5.2
That is its strongest area.
Claude Fable 5: where it fits
Anthropic's top public Mythos-class model and its most capable yet, though tier access was temporarily suspended in June 2026 under a US export-control directive. Released June 9, 2026 by Anthropic, it is built for the hardest reasoning and most complex problems, long-horizon, multi-step agentic work, frontier-level analysis and research, and work where maximum capability outweighs cost.
Its trade-offs are real: highest price in the Claude lineup, and tier access was temporarily suspended in June 2026 under a US export-control directive. At $10 in / $50 out per million tokens, it sits in the premium price band.
GPT-5.2: where it fits
A capable GPT-5-generation all-rounder, now succeeded by GPT-5.5. Released December 11, 2025 by OpenAI, it is built for strong all-round reasoning, reliable structured output, broad ecosystem and tooling, and professional workflows.
Its trade-offs: superseded by GPT-5.5, and smaller context than flagships. At $1.75 in / $14 out per million tokens, it sits in the mid price band.
The bottom line for this matchup
Claude Fable 5 and GPT-5.2 overlap enough that the right pick depends on your specific job. GPT-5.2 costs less per token; Claude Fable 5 holds the larger context; and each leads in its own area — Claude Fable 5 for the hardest reasoning and most complex problems, GPT-5.2 for strong all-round reasoning. Rather than crowning one, run the same hard task through both once and let the results decide.
Want both Claude Fable 5 and GPT-5.2 without two subscriptions? LumiChats gives you these plus 40+ models under one ₹69/day pass (about $1/day) — draft with one, cross-check with the other.
See pricingFrequently asked questions
Is Claude Fable 5 or GPT-5.2 better for coding?
Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, Claude Fable 5 leans toward the hardest reasoning and most complex problems while GPT-5.2 leans toward strong all-round reasoning, and that positioning usually predicts which feels better on your codebase.
Which is cheaper, Claude Fable 5 or GPT-5.2?
GPT-5.2 is cheaper — $10/$50 per 1M tokens vs $1.75/$14 per 1M tokens, roughly 5.7× apart on input.
Which has the bigger context window?
Claude Fable 5 — 1M vs 400K, about 2.5× larger. Useful only if the model actually reasons over the full window, which not all do.
Can I use both Claude Fable 5 and GPT-5.2 together?
Yes — a multi-model platform like LumiChats gives you Claude Fable 5, GPT-5.2 and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.
Which is newer, Claude Fable 5 or GPT-5.2?
Claude Fable 5 — released June 9, 2026, about 6 months after GPT-5.2.
Related comparisons
Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.