Standard Compute
Model comparison 2026

Claude Fable 5.1 vs Claude Opus 4.8

Claude Fable 5.1
Anthropic · Frontier · Proprietary
$22/1M · 1M ctx
Claude Opus 4.8
Anthropic · Frontier · Proprietary
$11/1M · 1M ctx

Community vote

Pick a winner in each dimension. You can change your vote any time.

Output Quality
Correctness and depth of what it produces
Agentic Ability
Tool calls, instruction-following, and multi-step tasks
Speed
Tokens per second and time-to-first-token
Value for money
How much capability you get per dollar
Reliability
Consistent results: fewer refusals, loops and format breaks

Specs and pricing side by side

Spec
Fable 5.1
Opus 4.8
Maker
Anthropic
Anthropic
Blended price / 1M
$22
$11
Input / output
$10 in · $50 out / 1M tokens
$5.00 in · $25 out / 1M tokens
Context window
1M
1M
Open weights
No
No
Tool use
Yes
Yes
Reasoning
Yes
Yes
Output Quality
9.7
9.4
Agentic Ability
9.7
9.2
Speed
6.7
7.2
Value for money
6.9
7.5
Reliability
9.6
9.5

Pricing and capabilities synced from the OpenRouter catalogue. Scores are editorial (0–10).

Verdict: Fable 5.1 or Opus 4.8?

Updated 2026-10-13

Choose Claude Fable 5.1 if you want teams already standardized on Fable that want the newest premium Claude. Choose Claude Opus 4.8 if you want hard, high-stakes coding and reasoning where quality matters more than cost.

In our editorial scoring, Claude Fable 5.1 leads in 3 of five dimensions (output quality, agentic ability and reliability), while Claude Opus 4.8 leads in 2. On price, Claude Fable 5.1 runs about $22 per 1M tokens (blended) and is proprietary; Claude Opus 4.8 is about $11 and proprietary.

Where Fable 5.1 falls short
  • Opus 5.5 scores higher on Artificial Analysis and Terminal-Bench 4.0 at less than half the price
  • Slow: about 67 output tokens/s at max effort
Full Fable 5.1 breakdown →
Where Opus 4.8 falls short
  • Among the most expensive models per token
  • Superseded by Claude Opus 5.5, which costs less ($4/$20 vs $5/$25) and scores far higher
Full Opus 4.8 breakdown →

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