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BenchLM
Anthropic logo
Model A
Claude Fable 5

Anthropic

80.9/100

Supported · Public rank #3

90% interval 78.7–83.1

Claude Fable 5 vs Claude Opus 4.8

Updated September 4, 2026. Public scores include evidence status and uncertainty. They are not guarantees for a specific workload.

Anthropic logo
Model B
Claude Opus 4.8

Anthropic

72.3/100

Supported · Public rank #11

90% interval 69.9–74.7

Decision reading

Claude Fable 5 has the higher public score, 80.9 versus 72.3, and the 90% score intervals do not overlap.

15 results are shared. Category rows resting on Estimated evidence or different benchmark sets are marked directional and do not name a winner.

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Which one for your work

Recommendations appear only when a shared evidence basis or an explicit operating constraint supports the call. Secondary and unsupported use cases stay disclosed below the initial list.

  • Coding work

    Code generation, repair, and software-engineering tasks

    Claude Fable 5

    Claude Fable 5 leads on the public coding lane, 76.9 to 66.5, with Supported evidence for both models, although the 90% intervals overlap.

    Confidence: limited

  • Agentic work

    Tool use, computer use, and multi-step task completion

    Claude Fable 5

    Claude Fable 5 leads on the public agentic lane, 74.8 to 63.2, with Supported evidence for both models, although the 90% intervals overlap.

    Confidence: limited

  • Chat turn cost

    1K fresh input + 500 output tokens

    Claude Opus 4.8

    Claude Opus 4.8 has the lower estimated token cost for this stated workload. Costs use the listed standard API rates.

    Confidence: listed-rates

Show secondary and unsupported calls

  • Cache-heavy agent loop cost

    200K cached + 20K fresh input + 10K output tokens

    Claude Fable 5

    Claude Fable 5 has the lower estimated token cost for this stated workload. Claude Opus 4.8 has no published cached-input rate, so cached tokens use its listed input rate.

    Confidence: rate-fallback

  • Repository review cost

    50K fresh input + 3K output tokens

    Claude Opus 4.8

    Claude Opus 4.8 has the lower estimated token cost for this stated workload. Costs use the listed standard API rates.

    Confidence: listed-rates

  • Long documents

    Prompts that approach the documented context limit

    No clear pick

    The documented context windows are equal.

    Confidence: documented

What is actually comparable

Shared results can support a head-to-head reading. Results present for only one model describe coverage, not superiority.

Shared results
15
Claude Fable 5 only
3
Claude Opus 4.8 only
23
Like-for-like categories
3 / 8

2 categories rest on Estimated evidence or different evidence sets. Those rows remain visible for coverage context but do not name a winner.

Category results, on a stated basis

Each row shows the public-lane category score for both models: the BenchAlign lane for agentic, coding, and knowledge, and the weighted public rows elsewhere, with the same rank each model page reports. A row is like-for-like only when both scores rest on Supported evidence or the same weighted set. Directional and not-comparable rows remain visible, but they never receive a winner.

Agentic

Like-for-like
Claude Fable 5
74.8
Supported · #3/151
Claude Opus 4.8
63.2
Supported · #16/151
Basis
BenchAlign lane · 4 vs 12 public rows
Reading
Claude Fable 5 leads · intervals overlap

Coding

Like-for-like
Claude Fable 5
76.9
Supported · #2/183
Claude Opus 4.8
66.5
Supported · #12/183
Basis
BenchAlign lane · 10 vs 10 public rows
Reading
Claude Fable 5 leads · intervals overlap

Knowledge

Like-for-like
Claude Fable 5
83.5
Supported · #2/181
Claude Opus 4.8
71.7
Supported · #9/181
Basis
BenchAlign lane · 2 vs 6 public rows
Reading
Claude Fable 5 leads · intervals overlap

Reasoning

Directional only
Claude Fable 5
76.2
#11/22
Claude Opus 4.8
55.1
#20/22
Basis
Provisional lane · 0 vs 2 weighted rows
Reading
Directional only

Instruction following

Directional only
Claude Fable 5
78.3
#54/120
Claude Opus 4.8
75.2
#59/120
Basis
Provisional lane · 0 vs 0 weighted rows
Reading
Directional only

Math

Not comparable
Claude Fable 5
Not ranked
Claude Opus 4.8
65.4
#2/7
Basis
Provisional lane · 0 vs 3 weighted rows
Reading
Not comparable

Multilingual

Not comparable
Claude Fable 5
Not ranked
Claude Opus 4.8
Not ranked
Basis
Provisional lane · 0 vs 0 weighted rows
Reading
Not comparable

Multimodal

Not comparable
Claude Fable 5
62.5
Unranked · 2 rankable rows
Claude Opus 4.8
87.8
#3/48
Basis
Provisional lane · 1 vs 2 weighted rows
Reading
Not comparable

Ranks count the models scored in each category’s lane, so the agentic, coding, and knowledge denominators (BenchAlign) differ from the provisional-lane categories. Unranked scores sit on the lane’s scale but never name a winner. Like-for-like rows within 0.5 points read as a practical tie.

Shape of the matched evidence

Only shared public evidence is shown. Sparse evidence stays a ruled list rather than being closed into a radar shape.

Too few matched category axes support a radar. The ruled list below shows only shared benchmark results; positions use each benchmark’s normalized display scale when available.

What each workload costs

Three fixed token mixes turn per-token rates into comparable decisions. Each scenario states context fit and whether cached input had to fall back to the published list-input rate.

Chat turn

1K fresh input + 500 output tokens

Claude Fable 5
$0.035
Fits in one request
Claude Opus 4.8
$0.0175
Fits in one request

Claude Opus 4.8 has the lower modeled cost

Costs use the listed standard API rates.

Repository review

50K fresh input + 3K output tokens

Claude Fable 5
$0.65
Fits in one request
Claude Opus 4.8
$0.325
Fits in one request

Claude Opus 4.8 has the lower modeled cost

Costs use the listed standard API rates.

Cache-heavy agent loop

200K cached + 20K fresh input + 10K output tokens

Claude Fable 5
$0.9
Fits in one request
Claude Opus 4.8
$1.35
Fits in one request
Cached input priced at the published list-input rate

Claude Fable 5 has the lower modeled cost

Claude Opus 4.8 has no published cached-input rate, so cached tokens use its listed input rate.

Specification differences

Sourced differences are shown directly. Missing facts stay explicit instead of being inferred from a model name or family.

Cached-input rate

A missing cached-input rate falls back to the listed input rate only in the stated workload estimate.

Claude Fable 5

$1 per 1M cached input tokens

Claude API pricing

Claude Opus 4.8

Not published

Reasoning profile

Claude Fable 5

Reasoning

Claude Opus 4.8

Reasoning

Weight access

Claude Fable 5

Proprietary

Claude Opus 4.8

Proprietary

License

Claude Fable 5

Proprietary

Claude Opus 4.8

Proprietary

Release date

Claude Fable 5

2026-06-09

Claude Opus 4.8

2026-05-28

If you already use one of these models
Deployment change
Both entries list Anthropic as the provider. Confirm endpoint, model ID, limits, and feature support before switching.
Quality signal
Claude Fable 5 has the higher public score, 80.9 versus 72.3, and the 90% score intervals do not overlap.
Workload cost
Repository review: $0.65 vs $0.325. Cache-heavy agent loop: $0.9 vs $1.35.
Context tradeoff
Both models list 1M.

Run the same representative tasks against both endpoints before changing production traffic.

Benchmark evidence

The full public result ledger is available for audit without forcing a wide desktop table onto a phone.

Browse raw public benchmark evidence41 rows

Agentic

  • Terminal-Bench 3.0

    Shared source
    Claude Fable 534.0%
    Claude Opus 4.821.1%

    Claude Fable 5 leads this result

  • Terminal-Bench 2.0

    Claude Fable 584.3%
    Source
    Claude Opus 4.874.6%
    Source

    Claude Fable 5 leads this result

  • OSWorld-Verified

    Claude Fable 585%
    Source
    Claude Opus 4.883.4%
    Source

    Claude Fable 5 leads this result

  • Terminal-Bench 2.1 (Vals)

    Claude Fable 580.5%
    Source
    Claude Opus 4.871.9%
    Source

    Claude Fable 5 leads this result

  • BrowseComp

    Claude Fable 5—
    Claude Opus 4.884.3%
    Source

    Not directly comparable

  • DeepSearchQA

    Claude Fable 5—
    Claude Opus 4.893.1%
    Source

    Not directly comparable

  • Finance Agent v2

    Claude Fable 5—
    Claude Opus 4.853.9%
    Source

    Not directly comparable

  • MCP Atlas

    Claude Fable 5—
    Claude Opus 4.882.2%
    Source

    Not directly comparable

  • Toolathlon

    Claude Fable 5—
    Claude Opus 4.859.9%
    Source

    Not directly comparable

  • Gert Labs

    Claude Fable 5—
    Claude Opus 4.872.97%
    Source

    Not directly comparable

  • ResearchClawBench

    Claude Fable 5—
    Claude Opus 4.821.1%
    Source

    Not directly comparable

  • OSWorld 2.0

    Claude Fable 5—
    Claude Opus 4.820.6%
    Source

    Not directly comparable

Coding

  • SWE-bench Verified

    Claude Fable 595%
    Source
    Claude Opus 4.888.6%
    Source

    Claude Fable 5 leads this result

  • SWE-bench Pro

    Claude Fable 580%
    Source
    Claude Opus 4.869.2%
    Source

    Claude Fable 5 leads this result

  • FrontierSWE v2

    Claude Fable 548.0%
    Source
    Claude Opus 4.8—

    Not directly comparable

  • FrontierCode 1.1 Main

    Shared source
    Claude Fable 553.5%
    Claude Opus 4.846.5%

    Claude Fable 5 leads this result

  • Terminal-Bench 2.0

    Claude Fable 584.3%
    Source
    Claude Opus 4.874.6%
    Source

    Claude Fable 5 leads this result

  • cursorBench31

    Shared source
    Claude Fable 570.6%
    Claude Opus 4.858.4%

    Claude Fable 5 leads this result

  • cursorBench32

    Shared source
    Claude Fable 570.5%
    Claude Opus 4.862.3%

    Claude Fable 5 leads this result

  • VulcanBench v3

    Claude Fable 589.5%
    Source
    Claude Opus 4.8—

    Not directly comparable

  • LiveCodeBench (Vals)

    Claude Fable 589.8%
    Source
    Claude Opus 4.887.8%
    Source

    Claude Fable 5 leads this result

  • SWE-bench (Vals)

    Claude Fable 595.0%
    Source
    Claude Opus 4.888.6%
    Source

    Claude Fable 5 leads this result

  • SWE Multilingual

    Claude Fable 5—
    Claude Opus 4.884.4%
    Source

    Not directly comparable

  • SWE Multimodal

    Claude Fable 5—
    Claude Opus 4.838.4%
    Source

    Not directly comparable

Reasoning

  • ARC-AGI-2

    Claude Fable 5—
    Claude Opus 4.872.1%
    Source

    Not directly comparable

  • ARC-AGI-3

    Claude Fable 5—
    Claude Opus 4.81.5%
    Source

    Not directly comparable

Knowledge

  • GPQA Diamond (Vals)

    Claude Fable 593.2%
    Source
    Claude Opus 4.892.4%
    Source

    Claude Fable 5 leads this result

  • MMLU-Pro (Vals)

    Claude Fable 591.5%
    Source
    Claude Opus 4.889.6%
    Source

    Claude Fable 5 leads this result

  • GPQA

    Claude Fable 5—
    Claude Opus 4.893.6%
    Source

    Not directly comparable

  • GPQA-D

    Claude Fable 5—
    Claude Opus 4.893.6%
    Source

    Not directly comparable

  • HLE

    Claude Fable 5—
    Claude Opus 4.857.9%
    Source

    Not directly comparable

  • HLE w/o tools

    Claude Fable 5—
    Claude Opus 4.849.8%
    Source

    Not directly comparable

Math

  • USAMO 2026

    Claude Fable 5—
    Claude Opus 4.896.7%
    Source

    Not directly comparable

  • FrontierMath v2 (Tiers 1-3)

    Claude Fable 5—
    Claude Opus 4.847.241%
    Source

    Not directly comparable

  • FrontierMath v2 (Tier 4)

    Claude Fable 5—
    Claude Opus 4.831.250%
    Source

    Not directly comparable

Multilingual

  • INCLUDE

    Claude Fable 5—
    Claude Opus 4.887.6%
    Source

    Not directly comparable

Multimodal

  • Blueprint-Bench 2

    Claude Fable 538.6%
    Source
    Claude Opus 4.8—

    Not directly comparable

  • OfficeQA Pro

    Claude Fable 557.9%
    Source
    Claude Opus 4.866.2%
    Source

    Claude Opus 4.8 leads this result

  • ScreenSpot Pro

    Claude Fable 5—
    Claude Opus 4.887.9%
    Source

    Not directly comparable

  • CharXiv

    Claude Fable 5—
    Claude Opus 4.889.9%
    Source

    Not directly comparable

  • CharXiv w/o tools

    Claude Fable 5—
    Claude Opus 4.880.5%
    Source

    Not directly comparable

Frequently asked questions

Which is better, Claude Fable 5 or Claude Opus 4.8?

Claude Fable 5 has the higher public score, 80.9 versus 72.3, and the 90% score intervals do not overlap. That is the clearest overall quality signal in the current public data.

Which is better for coding, Claude Fable 5 or Claude Opus 4.8?

Claude Fable 5 leads the public coding lane, 76.9 to 66.5, with Supported evidence for both models, although the 90% intervals overlap.

Which is better for agentic tasks, Claude Fable 5 or Claude Opus 4.8?

Claude Fable 5 leads the public agentic tasks lane, 74.8 to 63.2, with Supported evidence for both models, although the 90% intervals overlap.

Which costs less, Claude Fable 5 or Claude Opus 4.8?

For the stated presets, chat costs $0.035 on Claude Fable 5 and $0.0175 on Claude Opus 4.8; repository review costs $0.65 and $0.325; the cache-heavy agent loop costs $0.9 and $1.35. Claude Opus 4.8 has no published cached-input rate, so cached tokens use its listed input rate.

Which has the larger context window, Claude Fable 5 or Claude Opus 4.8?

Both models list the same context window, 1M.

Related comparisons

Compare API pricing Read the methodology Open the model selector

Last updated September 4, 2026

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