Standard Compute
Model comparison 2026

Claude Fable 5.1 vs Claude Sonnet 5.5

Claude Fable 5.1
Anthropic · Frontier · Proprietary
$22/1M · 1M ctx
Claude Sonnet 5.5
Anthropic · Balanced · Proprietary
$4.40/1M · 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
Sonnet 5.5
Maker
Anthropic
Anthropic
Blended price / 1M
$22
$4.40
Input / output
$10 in · $50 out / 1M tokens
$2.00 in · $10 out / 1M tokens
Context window
1M
1M
Open weights
No
No
Tool use
Yes
Yes
Reasoning
Yes
Yes
Output Quality
9.7
9.8
Agentic Ability
9.7
9.8
Speed
6.7
8.4
Value for money
6.9
8.8
Reliability
9.6
9.4

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

Verdict: Fable 5.1 or Sonnet 5.5?

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 Sonnet 5.5 if you want the everyday default for coding agents, escalating to Opus 5.5 only for the hardest tasks.

In our editorial scoring, Claude Sonnet 5.5 leads in 4 of five dimensions (output quality, agentic ability, speed and value for money), while Claude Fable 5.1 leads in 1. On price, Claude Fable 5.1 runs about $22 per 1M tokens (blended) and is proprietary; Claude Sonnet 5.5 is about $4.40 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 Sonnet 5.5 falls short
  • Artificial Analysis flags it as very verbose, which adds output tokens
  • Released September 2026, so its long-run track record is still short
Full Sonnet 5.5 breakdown →

The agent matters as much as the model. Compare AI agents →

Every model on this page is included with Standard Compute

Standard Compute

Current frontier models Claude Opus 5.5 · Claude Sonnet 5.5

Your agents never stop.
Your bill never grows.

Frontier models when it counts. Efficient models when it doesn’t. The most intelligence per dollar. One flat bill.

Plans from $19/mo · cancel anytime · 7-day fair refund

7-day fair refund No credit card needed Billing by Stripe1,800+ agent users

Related comparisons