AI IDE List

Anthropic / Model guide

Claude Fable 5.1

Compare Fable's capacity, API cost and reported results with the current Opus model.

Model facts

Context window
1M
Max output
128K
Input / 1M tokens
$10
Output / 1M tokens
$50

Adaptive, always on · high by default. Text and images in; text out. Reviewed 2026-09-25.

Official model documentation

Examples to explore

All 0 examples
No published cases in this collection yet. Explore the Opus 5.5 collection.

API pricing

$10 input · $50 output · $0.25 cache read per million tokens.

Standard input/output rates per million tokens. Check the official pricing documentation for caching and service tiers.

Official pricing

Reported benchmarks

Anthropic launch benchmarks, September 22, 2026
BenchmarkClaude Fable 5.1
Terminal-Bench 4.0Opus 5.5: xhigh effort55.8%
FrontierCode v1.1Opus 5.5: max effort50.3%
CursorBench 4.0Opus 5.5: max effort51.8%
GDPval-AA v2.1Opus 5.5: max effort1735 Elo
AutomationBenchOpus 5.5: max effort31.4%
Humanity's Last ExamWith tools · Opus 5.5: max effort65.6%

Vendor-reported launch results, September 22, 2026. Opus 5.5 uses max effort except Terminal-Bench (xhigh). Other models' effort, harness and tool settings can differ; see the original methodology. These are not AI IDE List tests and are separate from Anthropic's medium-effort cost charts.

Benchmark source and methodology

Compare Claude Fable 5.1

Claude Opus 5.5 vs Claude Fable 5.1

Both offer a 1M context window and 128K output. Opus 5.5 has 60% lower standard input and output rates; the best choice still depends on task quality.

View comparison