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AI Choice Engine

Model comparison

Claude Fable 5.1 vs Claude Haiku 4.5

Two Anthropic tiers compared on the figures that decide which one a workload actually needs.

Recorded profile verification October 1, 2026Individual provider fields may changeEvidence confidence: Medium — see receipts below

Anthropic

Claude Fable 5.1

Frontier

vs

Anthropic

Claude Haiku 4.5

Budget

AI model capability comparison
SpecificationClaude Fable 5.1Claude Haiku 4.5
ProviderAnthropicAnthropic
TierFrontierBudget
Context windowWinner: 1M200K
Max outputWinner: 128K64K
Input / 1M tokens$10Winner: $1
Output / 1M tokens$50Winner: $5
WeightsClosedClosed
ParametersNot verifiedUnverifiedNot verifiedUnverified
Reasoning levelslow, medium, high, xhigh, maxextended thinking (budget_tokens)
Modalitiestext, imagetext, image
API model idclaude-fable-5-1claude-haiku-4-5-20251001
ReleasedSeptember 1, 2026October 15, 2025
Artificial Analysis Intelligence Index [max] · source date Claude Fable 5.1: 2026-10-0153Not verifiedUnverified
Humanity's Last Exam · source date Claude Fable 5.1: 2026-09-0165Not verifiedUnverified
Terminal-Bench 2.1 · source date Claude Fable 5.1: 2026-09-2691.4Not verifiedUnverified
DeepSWE 1.1 · source date Claude Fable 5.1: 2026-09-0367.4Not verifiedUnverified
SWE-bench Verified [high] · source date Claude Haiku 4.5: 2026-02-17Not verifiedUnverified66.6
SWE-bench Verified · source date Claude Haiku 4.5: 2025-10-15Not verifiedUnverified73.3
Terminal-Bench · source date Claude Haiku 4.5: 2025-10-15Not verifiedUnverified40.21

Dates beside benchmark scores refer to the linked source’s publication or capture date unless that source explicitly states when it measured the result. A shared URL alone does not establish comparable runs; unverified setups are marked. Prices are USD per million tokens at standard rates, excluding batch and caching discounts. Values we could not confirm from the provider are shown as “Not verified” rather than estimated.

Benchmark receipts

Where each score comes from, and how far it can be compared across models.

Pricing tiers

Claude Fable 5.1: Standard $10/$50 per MTok with no long-context surcharge. Cache reads $0.25, versus Fable 5's $1; 5-minute writes $12.50 and 1-hour writes $20. Batch $5/$25. US-only inference adds 10% where supported. Adaptive thinking is always on, default effort high; knowledge cutoff Jun 2026. Retirement not sooner than September 1, 2027.

Claude Haiku 4.5: Standard $1/$5 per MTok; cache reads $0.10, 5-minute writes $1.25 and 1-hour writes $2. Batch $0.50/$2.50. Context 200K and output 64K. Reliable knowledge cutoff Feb 2025; training cutoff Jul 2025. The alias claude-haiku-4-5 resolves to claude-haiku-4-5-20251001. Retirement not sooner than October 15, 2026; no definite shutdown is announced.

FrontierRecord checked October 1, 2026

Claude Fable 5.1

Claude Fable 5.1 is Anthropic's model for the most demanding reasoning and long-horizon agentic work at $10/$50 — Anthropic now recommends Opus 5.5 as the default for most workloads.

Best for

  • Frontier agents
  • Hardest reasoning work
  • Fable 5 workloads at the same price

Watch out

Standard token rates are 2.5x Opus 5.5's. Forced tool use errors; thinking blocks are model/conversation-bound, so editing earlier turns or switching models can invalidate them. Display updates and per-message effort are beta. Match benchmark settings and evaluate pinned workloads before migrating.

BudgetRecord checked October 1, 2026

Claude Haiku 4.5

Claude Haiku 4.5 is Anthropic's lower-cost Haiku tier for high-volume classification and extraction at $1/$5 per million input/output tokens.

Best for

  • High-volume classification
  • Routine extraction
  • Latency-sensitive stacks

Watch out

No adaptive thinking (manual extended thinking via budget_tokens only); 200K context. Anthropic lists 2026-10-15 as the earliest possible retirement date, and Haiku 5.5 is announced but not released.

When the cheaper one wins

Claude Haiku 4.5 is cheaper on output at $5 per million tokens against $50 for Claude Fable 5.1 — about 10×. Use the cheaper tier for classification, extraction, summarisation, and any task where the expensive model’s extra score does not change the accepted output. The expensive one only pays if your hardest task actually fails on the cheap tier. This compares standard short-context token rates, not total cost per accepted task. Include input, cache, context tiers, schedules, retries and review in your pilot.

Run the model picker

Evidence confidence: Medium

How strong and complete the evidence behind this comparison is — not a prediction of which model is better.

  • Pricing verified on both sides — Input and output rates are verified for both models.
  • 4/5 core specs verified on both sides — Not published for at least one side: parameter count.
  • No directly aligned benchmark setup — No benchmark has matching cited sources, source dates, units, effort and recorded run details on both models.
  • Verified within the last 90 days — Older of the two catalog checks was 25 days ago.
  • Both models carry source citations — Each side has at least two catalog sources on record.

Source receipts

Each catalog figure was checked against the provider or an independent second source on the date shown.

Related comparisons

Diving deeper on one model? Claude Fable 5.1 · Claude Haiku 4.5

Common questions

Claude Fable 5.1 vs Claude Haiku 4.5

Answered from the verified figures on this page rather than general guidance.

Is Claude Fable 5.1 or Claude Haiku 4.5 cheaper for input?
Claude Haiku 4.5 is cheaper at $1 per million input tokens, against $10 for Claude Fable 5.1 — roughly 10× the price. Estimate both input and output token volume for your workload. These are base rates; Claude Fable 5.1: Standard $10/$50 per MTok with no long-context surcharge. Cache reads $0.25, versus Fable 5's $1; 5-minute writes $12.50 and 1-hour writes $20. Batch $5/$25. US-only inference adds 10% where supported. Adaptive thinking is always on, default effort high; knowledge cutoff Jun 2026. Retirement not sooner than September 1, 2027. Claude Haiku 4.5: Standard $1/$5 per MTok; cache reads $0.10, 5-minute writes $1.25 and 1-hour writes $2. Batch $0.50/$2.50. Context 200K and output 64K. Reliable knowledge cutoff Feb 2025; training cutoff Jul 2025. The alias claude-haiku-4-5 resolves to claude-haiku-4-5-20251001. Retirement not sooner than October 15, 2026; no definite shutdown is announced.
Is Claude Fable 5.1 or Claude Haiku 4.5 cheaper for output?
Claude Haiku 4.5 is cheaper at $5 per million output tokens, against $50 for Claude Fable 5.1 — roughly 10× the price. Estimate both input and output token volume for your workload. These are base rates; Claude Fable 5.1: Standard $10/$50 per MTok with no long-context surcharge. Cache reads $0.25, versus Fable 5's $1; 5-minute writes $12.50 and 1-hour writes $20. Batch $5/$25. US-only inference adds 10% where supported. Adaptive thinking is always on, default effort high; knowledge cutoff Jun 2026. Retirement not sooner than September 1, 2027. Claude Haiku 4.5: Standard $1/$5 per MTok; cache reads $0.10, 5-minute writes $1.25 and 1-hour writes $2. Batch $0.50/$2.50. Context 200K and output 64K. Reliable knowledge cutoff Feb 2025; training cutoff Jul 2025. The alias claude-haiku-4-5 resolves to claude-haiku-4-5-20251001. Retirement not sooner than October 15, 2026; no definite shutdown is announced.
Which has the larger context window, Claude Fable 5.1 or Claude Haiku 4.5?
Claude Fable 5.1 accepts 1M tokens against 200K for Claude Haiku 4.5. This only matters if you routinely send very long documents or large codebases.
Do Claude Fable 5.1 and Claude Haiku 4.5 support the same reasoning levels?
Claude Fable 5.1 exposes low, medium, high, xhigh, max, while Claude Haiku 4.5 exposes extended thinking (budget_tokens).
Should I use Claude Fable 5.1 or Claude Haiku 4.5?
We classify Claude Fable 5.1 in the frontier tier and Claude Haiku 4.5 in the budget tier. Test whether either meets your accuracy, tool-use and latency requirements before choosing on price.

Next step

Choosing between them

The verified figures that separate this pair, computed from the catalog rather than restated boilerplate.

  • Input price: Claude Haiku 4.5 costs $1 per 1M tokens versus $10 for Claude Fable 5.1 — a 10x difference at the headline tier.
  • Context: Claude Fable 5.1 takes 1M against 200K for Claude Haiku 4.5 — only decisive if your prompts approach the smaller window.
  • Positioning: Claude Fable 5.1 sits in the frontier tier, Claude Haiku 4.5 in the budget tier. Compare accuracy, reliability, latency, and cost on representative tasks before choosing.
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