Noometry

Model comparison

Claude Haiku 4.5 vs Mercury 2.5

Claude Haiku 4.5 is the stronger model overall, scoring 39.5 to 33.5 on the Noometry Index. Mercury 2.5 costs 30× less per token, which makes it the better buy when Claude Haiku 4.5's lead doesn't matter for your workload.

Last verified . 3 shared benchmarks.

Claude Haiku 4.5 Anthropic

39.5

Rank #165 Confirmed

Mercury 2.5 Inception

33.5

Rank #242 Reported

Summary

  • They share 3 benchmarks with published results for both. Claude Haiku 4.5 scores higher in 2 categories and Mercury 2.5 in 1 category; 3 gaps are clear of the uncertainty.
  • The widest gap is in math, where Claude Haiku 4.5 leads 44.9 to 23.3.
  • Mercury 2.5 is cheaper at $0.04 / $0.15 per million input/output tokens, against $1 / $5 for Claude Haiku 4.5.
  • Mercury 2.5 accepts more context: 260K tokens versus 200K.

Side by side

Claude Haiku 4.5Mercury 2.5
ProviderAnthropicInception
Noometry Index39.533.5
Released2025-10-152026-09-08
WeightsProprietaryProprietary
Context window200K260K
Max output64K66K
Input $ / M tokens$1$0.04
Output $ / M tokens$5$0.15
Results tracked534

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Category by category

Coding Claude Haiku 4.5 leads

Claude Haiku 4.5: 44.0 (#78), Mercury 2.5: 39.5 (#156)

BenchmarkClaude Haiku 4.5Mercury 2.5
SciCode43.3%38.5%
ALE-Bench653.48301.65
SWE-bench Verified (bash only)66.6%—
LMArena WebDev1330—
SWE-bench Multilingual64.7%—
WeirdML45.4%—
LMArena Coding1453—

Agentic & Tool Use Not comparable

Claude Haiku 4.5: 33.6 (#52), Mercury 2.5: —

BenchmarkClaude Haiku 4.5Mercury 2.5
Terminal-Bench35.5%—
Berkeley Function Calling Leaderboard68.7%—
DeepResearch Bench45.5%—
BALROG31.2%—
ExploitBench13.7%—
Vending-Bench 2458.89—

Reasoning Mercury 2.5 leads

Claude Haiku 4.5: 15.1 (#320), Mercury 2.5: 22.4 (#193)

BenchmarkClaude Haiku 4.5Mercury 2.5
CritPt0%0%
ARC-AGI-24%—
NYT Connections (extended)14.3%—
ARC-AGI-147.7%—
Chess Puzzles8%—
LMArena Hard Prompts1420—
DTBench73.6%—
LMCA30.9%—
Epoch Capabilities Index142.41—
ForecastBench61.4—

Math Claude Haiku 4.5 leads

Claude Haiku 4.5: 44.9 (#78), Mercury 2.5: 23.3 (#272)

BenchmarkClaude Haiku 4.5Mercury 2.5
OTIS Mock AIME 2024-202566.7%—
ProofBench—3%
Omni-MATH56.1%—
LMArena Math1396—
MATH Level 596.4%—
FrontierMath (Feb 2025 set)5.9%—
FrontierMath Tier 4 (v1)2.1%—

Knowledge Not comparable

Claude Haiku 4.5: 37.7 (#153), Mercury 2.5: —

BenchmarkClaude Haiku 4.5Mercury 2.5
GPQA Diamond71.2%—
SimpleQA Verified13.2%—
MMLU-Pro77.7%—
Vectara Hallucination Rate9.8%—
GPQA (HELM)60.5%—
LMArena Expert1442—

Multimodal Not comparable

Claude Haiku 4.5: 26.8 (#118), Mercury 2.5: —

BenchmarkClaude Haiku 4.5Mercury 2.5
Blueprint-Bench 20%—
LMArena Document1420—

Multilingual Not comparable

Claude Haiku 4.5: 49.9 (#129), Mercury 2.5: —

BenchmarkClaude Haiku 4.5Mercury 2.5
LMArena Non-English1377—
LMArena Chinese1417—
LMArena French1408—
LMArena German1375—
LMArena Japanese1339—
LMArena Korean1347—
LMArena Russian1381—
LMArena Spanish1420—

Instruction Following Not comparable

Claude Haiku 4.5: 71.4 (#149), Mercury 2.5: —

BenchmarkClaude Haiku 4.5Mercury 2.5
IFEval80.1%—
LMArena Instruction Following1414—

Long Context Not comparable

Claude Haiku 4.5: 43.6 (#92), Mercury 2.5: —

BenchmarkClaude Haiku 4.5Mercury 2.5
LMArena Longer Query1427—

Writing & Preference Not comparable

Claude Haiku 4.5: 57.9 (#123), Mercury 2.5: —

BenchmarkClaude Haiku 4.5Mercury 2.5
LMArena Text1396—
LMArena Creative Writing1372—
WildBench83.9%—
EQ-Bench 41064—
LMArena Multi-Turn1409—

Frequently asked questions

Is Claude Haiku 4.5 better than Mercury 2.5?

Claude Haiku 4.5 is the stronger model overall, scoring 39.5 to 33.5 on the Noometry Index. Mercury 2.5 costs 30× less per token, which makes it the better buy when Claude Haiku 4.5's lead doesn't matter for your workload.

Which is cheaper, Claude Haiku 4.5 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 Haiku 4.5 lists at $1 and $5.

Is Claude Haiku 4.5 or Mercury 2.5 better for coding?

Claude Haiku 4.5 scores higher on coding benchmarks: 44.0 versus 39.5 in the Noometry coding category.

Which has the bigger context window?

Mercury 2.5 does, with 260K tokens against 200K.

How many benchmarks do Claude Haiku 4.5 and Mercury 2.5 share?

3 benchmarks have published results for both models. Claude Haiku 4.5 has 53 scored results on Noometry and Mercury 2.5 has 4.

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