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Head-to-head comparison

Claude Fable 5.1 vs Claude Haiku 5.5

Claude Fable 5.1 (Anthropic) and Claude Haiku 5.5 (Anthropic) compared on the ModelCap Index, API price, context window, provider availability, weight access and every public benchmark board they share. Figures are the same ones shown on the live rankings; nothing here is a hidden score.

Snapshot as of 14 October 2026

As of 14 October 2026, Claude Fable 5.1 holds the stronger ModelCap Index position (#4 vs #59); and Claude Haiku 5.5 is 100× cheaper per output token ($0.50/1M vs $50.00/1M).

Which should you choose?

Choose Claude Fable 5.1 if…

  • you want the stronger overall ModelCap Index position — #4 against #59 (85.6 vs 63.5 points).
  • LMArena Agent is your yardstick — 14.3% against 1.5%.
  • AA Intelligence Index is your yardstick — 53.4 against 43.4.
  • AA Humanity's Last Exam is your yardstick — 59.1% against 44.4%.

Choose Claude Haiku 5.5 if…

  • API cost matters — $0.50/1M output tokens against $50.00/1M, about 100× cheaper.
  • your workload is prompt-heavy — input tokens cost $0.10/1M against $10.00/1M.
  • you want provider choice — 5 listed API providers against 4.
  • you want the more recently listed model — Claude Haiku 5.5 was listed 7 October 2026, Claude Fable 5.1 1 September 2026.

Claude Fable 5.1 vs Claude Haiku 5.5: specs, pricing and context

Specification comparison of Claude Fable 5.1 and Claude Haiku 5.5
FieldClaude Fable 5.1AnthropicClaude Haiku 5.5Anthropic
ModelCap Index position#4#59
Index score85.663.5
EvidenceMeasuredMeasured
Input price / 1M tokens$10.00$0.10
Output price / 1M tokens$50.00$0.50
Context window1M tokens1M tokens
Declared route output cap128K128K
API providers listed45
Weight accessNo linked weightsNo linked weights
Input modalitiesText, Image, FileText, Image, File
First listed1 September 20267 October 2026
PublisherAnthropicAnthropic

Evidence: 4 public benchmark observations across 4 boards · 1 reported rows against measured corpus ladders (24%); publisher-corpus-prior over 213 held-out anchors (14%); measured predecessor anthropic/claude-haiku-4.5 less the succession penalty (51%); 1 specialist-board observation at 2.5% support (11%); shrunk 2.3 up toward the measured corpus. Prices are the lowest listed API offer per million tokens observed on the OpenRouter catalogue.

Benchmark scores: Claude Fable 5.1 vs Claude Haiku 5.5

Public benchmark boards where Claude Fable 5.1 or Claude Haiku 5.5 has a published result
BoardClaude Fable 5.1Claude Haiku 5.5Leads
Arena textArena (LMArena)15011494–1507Max—Only one result
Arena codingArena (LMArena)15351524–1547Max—Only one result
LMArena AgentLMArena14.3%12.3%–16.4%Max1.5%0.5%–2.5%HighClaude Fable 5.1
ARC-AGI-2ARC Prize Foundation90.0%Max—Only one result
AA Intelligence IndexArtificial Analysis53.4Reasoning43.4MaxClaude Fable 5.1
AA Terminal-Bench 2.1Artificial Analysis91.4%Reasoning—Only one result
AA Humanity's Last ExamArtificial Analysis59.1%Reasoning44.4%MaxClaude Fable 5.1
Terminal-Bench 4.0Terminal-Bench (Laude Institute)57.9%54.1%–61.6%Claude Code · Max—Only one result

Scores are the sources' own published figures for each model's best evaluated configuration; ModelCap never re-runs a benchmark.

Want a different pairing? Open the interactive comparison tool to swap either model for any current ranked language model.

Claude Fable 5.1 vs Claude Haiku 5.5: common questions

Is Claude Fable 5.1 better than Claude Haiku 5.5?

Claude Fable 5.1 ranks higher on the ModelCap Index as of 14 October 2026: #4 against #59. That is a capability ranking built from public benchmark evidence with published uncertainty; whether it is "better" for you also depends on price, context and where you can run it. Their published uncertainty intervals do not overlap, but the aggregate Index does not predict performance on every task; compare the relevant benchmark configurations before choosing.

Is Claude Fable 5.1 cheaper than Claude Haiku 5.5?

Claude Haiku 5.5 is cheaper on output tokens: $0.50/1M against $50.00/1M. Input tokens are $10.00/1M for Claude Fable 5.1 and $0.10/1M for Claude Haiku 5.5. Prices are the lowest listed API offer ModelCap observed, in USD per million tokens. For 1,000 requests with 2,000 input and 500 output tokens each (2M input + 0.5M output), the listed-rate estimate is $45.00 for Claude Fable 5.1 versus $0.45 for Claude Haiku 5.5. Claude Haiku 5.5 costs 99.0% less in this scenario. This excludes caching, batch discounts, prompt-length tiers, tool charges and retries; verify the selected endpoint before budgeting.

Which has the bigger context window, Claude Fable 5.1 or Claude Haiku 5.5?

Both publish a 1M-token context window. OpenRouter catalogue or provider-endpoint declaration. Limits can vary by provider and prompt length; a model-wide maximum has not been independently verified.

Which is better for coding, Claude Fable 5.1 or Claude Haiku 5.5?

The two models do not share a coding benchmark board on ModelCap yet, so no head-to-head coding score is published; the ModelCap Index position is the closest overall signal.

Are Claude Fable 5.1 and Claude Haiku 5.5 open-weight models?

Claude Fable 5.1: No linked weights. Claude Haiku 5.5: No linked weights. Open weights mean the checkpoint can be downloaded and self-hosted under its licence. A missing weight link does not identify every API or chat product that offers a model.

Where can I run Claude Fable 5.1 and Claude Haiku 5.5?

ModelCap currently lists 4 API providers for Claude Fable 5.1 and 5 for Claude Haiku 5.5, from the OpenRouter catalogue snapshot the site serves; each model page lists the providers and their prices.

How current is this Claude Fable 5.1 vs Claude Haiku 5.5 comparison?

Every figure and ModelCap Index position comes from the same published snapshot dated 14 October 2026. Publication and page updates happen separately; use the snapshot date shown on the page.

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