Noometry

Model comparison

Claude Opus 4.8 vs Mercury 2.5

Claude Opus 4.8 has enough public results to be ranked (#9); Mercury 2.5 does not yet, so treat this comparison as directional.

Last verified . 2 shared benchmarks.

Claude Opus 4.8 Anthropic

60.7

Rank #9 Confirmed

Mercury 2.5 Inception

30.2

Unranked Sparse

Summary

  • They share 2 benchmarks with published results for both. Claude Opus 4.8 scores higher in 1 category and Mercury 2.5 in 0 categories; one gap is clear of the uncertainty.
  • The widest gap is in math, where Claude Opus 4.8 leads 78.2 to 22.4.
  • The biggest single-benchmark swing is ProofBench: 69% for Claude Opus 4.8 and 3% for Mercury 2.5.
  • Mercury 2.5 is cheaper at $0.04 / $0.15 per million input/output tokens, against $5 / $25 for Claude Opus 4.8.
  • Claude Opus 4.8 accepts more context: 1M tokens versus 260K.

Side by side

Claude Opus 4.8Mercury 2.5
ProviderAnthropicInception
Noometry Index60.730.2
Released2026-05-282026-09-08
WeightsProprietaryProprietary
Context window1M260K
Max output128K66K
Input $ / M tokens$5$0.04
Output $ / M tokens$25$0.15
Results tracked652

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Category by category

Coding Not comparable

Claude Opus 4.8: 60.2 (#9), Mercury 2.5: —

BenchmarkClaude Opus 4.8Mercury 2.5
ALE-Bench1,564301.65
DeepSWE59%—
FrontierCode46.5%—
LMArena WebDev1556—
SciCode53.5%—
GSO47.1%—
WeirdML82.9%—
LMArena Coding1491—

Agentic & Tool Use Not comparable

Claude Opus 4.8: 47.6 (#10), Mercury 2.5: —

BenchmarkClaude Opus 4.8Mercury 2.5
APEX-Agents48.9%—
OSWorld 2.020.6%—
Remote Labor Index8.3%—
τ²-bench Banking39.7%—
DeepResearch Bench50.2%—
PostTrainBench33.8%—
GBAEval70.9%—
GDP.pdf24%—
LMArena Search1204—
Vending-Bench 25,787—

Reasoning Not comparable

Claude Opus 4.8: 64.6 (#14), Mercury 2.5: —

BenchmarkClaude Opus 4.8Mercury 2.5
ARC-AGI-272.1%—
SimpleBench64.8%—
Kagi LLM Benchmark88.8%—
NYT Connections (extended)91.1%—
ARC-AGI-192.5%—
CritPt20.9%—
Chess Puzzles34%—
EnigmaEval23.5%—
EBR-Bench28.6%—
LMArena Hard Prompts1481—
Mystery Game Puzzles36%—
DTBench94.9%—
LMCA57.5%—
Surface Evolver Bench87.5%—
Bench to the Future 30.14—
Epoch Capabilities Index158.3—
ForecastBench59.9—

Math Claude Opus 4.8 leads

Claude Opus 4.8: 78.2 (#11), Mercury 2.5: 22.4

BenchmarkClaude Opus 4.8Mercury 2.5
ProofBench69%3%
FrontierMath (Tiers 1-3)80%—
FrontierMath Tier 456.1%—
MathArena Final-Answer Competitions91.8%—
OTIS Mock AIME 2024-202598.3%—
LMArena Math1487—
FrontierMath (Feb 2025 set)47.2%—
FrontierMath Tier 4 (v1)31.3%—

Knowledge Not comparable

Claude Opus 4.8: 61.3 (#26), Mercury 2.5: —

BenchmarkClaude Opus 4.8Mercury 2.5
GPQA Diamond91%—
SimpleQA Verified53%—
LMArena Expert1501—

Multimodal Not comparable

Claude Opus 4.8: 43.2 (#20), Mercury 2.5: —

BenchmarkClaude Opus 4.8Mercury 2.5
LMArena Vision1295—
Blueprint-Bench 214.5%—
Furniture Assembly42.5%—
LMArena Document1475—

Multilingual Not comparable

Claude Opus 4.8: 55.4 (#31), Mercury 2.5: —

BenchmarkClaude Opus 4.8Mercury 2.5
LMArena Non-English1450—
LMArena Chinese1509—
LMArena French1482—
LMArena German1470—
LMArena Japanese1440—
LMArena Korean1432—
LMArena Russian1476—
LMArena Spanish1470—

Instruction Following Not comparable

Claude Opus 4.8: 77.6 (#22), Mercury 2.5: —

BenchmarkClaude Opus 4.8Mercury 2.5
LMArena Instruction Following1476—

Long Context Not comparable

Claude Opus 4.8: 45.4 (#37), Mercury 2.5: —

BenchmarkClaude Opus 4.8Mercury 2.5
LMArena Longer Query1482—

Writing & Preference Not comparable

Claude Opus 4.8: 72.1 (#17), Mercury 2.5: —

BenchmarkClaude Opus 4.8Mercury 2.5
LMArena Text1460—
LMArena Creative Writing1453—
EQ-Bench Creative Writing1840—
EQ-Bench 41281—
LMArena Multi-Turn1476—

Frequently asked questions

Is Claude Opus 4.8 better than Mercury 2.5?

Claude Opus 4.8 has enough public results to be ranked (#9); Mercury 2.5 does not yet, so treat this comparison as directional.

Which is cheaper, Claude Opus 4.8 or Mercury 2.5?

Mercury 2.5 is cheaper. It lists at $0.04 per million input tokens and $0.15 per million output tokens; Claude Opus 4.8 lists at $5 and $25.

Which has the bigger context window?

Claude Opus 4.8 does, with 1M tokens against 260K.

How many benchmarks do Claude Opus 4.8 and Mercury 2.5 share?

2 benchmarks have published results for both models. Claude Opus 4.8 has 65 scored results on Noometry and Mercury 2.5 has 2.

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