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Anthropic: Claude Opus 4.8

Anthropic: Claude Opus 4.8 is anthropic's model. On the un-leaked meo benchmark it ranks #2 of 22 with 70.8% accuracy and an Effective Value (𝕍) of 0.0488 β€” earning a correct answer for about $0.0584 in 27s each.

as of 2026-06-08

meo rank
#2
of 22
Accuracy
70.8%
overall
𝕍 index (top=100)
100.0
raw 𝕍 0.0488 Β· N=10
$ / correct
$0.0584
27s each

Per-domain accuracy

CSP (unsatisfiable)
100%
Tape machine
100%
Watson-Glaser
100%
Theory of mind
100%
Long arithmetic
100%
Regex automaton
100%
Perceptual illusions
78%
Framework bias
67%
Base-rate bias
10%
Logic / math / CS
8%
State tracking
0%

Efficiency

Cost per correct
$0.0584
Seconds per correct
27
Tokens per correct
2,210
Correct answers
156 / 251
Total benchmark cost
$9.12
Avg tokens / item
1,373

Robustness under pressure

Susceptibility index -0.031 (Ξ”accuracy under threatening/emotional prompts; β‰ˆ0 = robust), sway magnitude 0.031. How we measure this β†’

control
58%
neutral
46%
user direct
54%
model direct
50%
user implied
58%
model implied
58%
positive control
46%

Aggregated third-party benchmarks

Artificial Analysis (artificialanalysis.ai). Redistribution requires an AA commercial license.

Model details

Lab
anthropic
Released
2026-05-27
Weights
β€”
Context
1M
Max output
128K
Knowledge cutoff
β€”
Price in
$5.00/M
Price out
$25.00/M
Modality
text+image+file->text

Sources: openrouter Β· artificial_analysis Β· meo

FAQ

How accurate is Anthropic: Claude Opus 4.8?

Anthropic: Claude Opus 4.8 scores 70.8% overall on the meo benchmark (rank #2 of 22), an un-leaked private holdout graded objective-first.

What is Anthropic: Claude Opus 4.8's Effective Value?

Its Effective Value (𝕍) is 0.0488 at N=10, Ο‰=1, Ξ΄=1.5 β€” a fused metric of accuracy, speed, cost, and error-cascade. 𝕍 rankings shift with task depth.

How much does Anthropic: Claude Opus 4.8 cost per correct answer?

About $0.0584 per correct answer (2,210 tokens, 27 seconds each) at benchmark-time pricing via OpenRouter.

Is Anthropic: Claude Opus 4.8 open weights?

Open-weights status for Anthropic: Claude Opus 4.8 is not recorded.