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BenchLM

Claude Opus 5.5 vs Mercury 2.5

Updated September 23, 2026. We do not rank this pair: at least one has no public score. Public scores include evidence status and uncertainty.

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Decision reading

The public evidence has no benchmark result shared by both models, so it does not support a quality verdict. Use the documented cost, context, and runtime rows instead. 0 results are shared. Category rows resting on Estimated evidence or different benchmark sets are marked directional and do not name a winner.

Model A
Anthropic logo
Claude Opus 5.5

Anthropic

88.45/100

Estimated · Public rank #2

90% interval 76.9–100.0

Model B
Inception logo
Mercury 2.5

Inception

—

Evidence status unavailable

90% interval unavailable

Shared results
0
Claude Opus 5.5 only
47
Mercury 2.5 only
6
Like-for-like categories
1 / 8
Estimated: Claude Opus 5.5How the comparison works

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.

  • Agentic work

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

    Claude Opus 5.5

    Claude Opus 5.5 leads on the public agentic lane, 88.8 to 12.4, with Supported evidence for both models and non-overlapping 90% intervals.

    Confidence: stronger

  • Long documents

    Prompts that approach the documented context limit

    Claude Opus 5.5

    Claude Opus 5.5 has the larger documented context window.

    Confidence: documented

  • Chat turn cost

    1K fresh input + 500 output tokens

    Mercury 2.5

    Mercury 2.5 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

    Mercury 2.5

    Mercury 2.5 has the lower estimated token cost for this stated workload. Costs use the listed standard API rates.

    Confidence: listed-rates

  • Repository review cost

    50K fresh input + 3K output tokens

    Mercury 2.5

    Mercury 2.5 has the lower estimated token cost for this stated workload. Costs use the listed standard API rates.

    Confidence: listed-rates

  • Coding work

    Code generation, repair, and software-engineering tasks

    Not enough matched evidence

    Mercury 2.5 is scored on Estimated evidence for coding, so the reading is directional rather than like-for-like.

    Confidence: limited

Which one for a specific job

Choose a job from the LLM Selector's task catalog to see the category row it rests on, under the same basis rules as the table below. A directional row stays directional; choosing a job never creates a winner.

The same task catalog as the LLM Selector. Each job names the evidence surface it rests on; nothing here adds a new score.

87.1Claude Opus 5.520.3Mercury 2.5

Directional only · BenchAlign v5.6

Claude Opus 5.5 scores higher, but at least one score rests on Estimated evidence or a different benchmark set. Directional only, no winner.

Coding scores combine specific tasks and setups. Match the editor, harness, and effort to your workflow.

Open the coding leaderboardShortlist models for this job
Same basis rules as the category table below

What is actually comparable

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

1 category rests on Estimated evidence or different evidence sets. Those rows remain visible for coverage context but do not name a winner.

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.

A shared-evidence shape is not available.

BenchLM does not draw a radar or infer missing axes when the matched evidence is too sparse.

Category results, on a stated basis

Each row shows the public-lane category score for both models: the BenchAlign v5.6 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 Opus 5.5
88.8
Supported · #1/105
Mercury 2.5
12.4
Supported · #100/105
Basis
BenchAlign v5.6 lane · 11 vs 3 public rows
Reading
Claude Opus 5.5 leads

Coding

Directional only
Claude Opus 5.5
87.1
Supported · #1/135
Mercury 2.5
20.3
Estimated · #128/135
Basis
BenchAlign v5.6 lane · 9 vs 1 public rows
Reading
Directional only

Reasoning

Not comparable
Claude Opus 5.5
78.5
#4/18
Mercury 2.5
67.7
Unranked · 1 rankable row
Basis
Provisional lane · 0 vs 0 weighted rows
Reading
Not comparable

Multimodal

Not comparable
Claude Opus 5.5
88.8
#3/50
Mercury 2.5
Not ranked
Basis
Provisional lane · 1 vs 0 weighted rows
Reading
Not comparable

Knowledge

Not comparable
Claude Opus 5.5
90.0
Supported · #1/160
Mercury 2.5
Not ranked
Basis
BenchAlign v5.6 lane · 16 vs 1 public rows
Reading
Not comparable

Multilingual

Not comparable
Claude Opus 5.5
Not ranked
Mercury 2.5
Not ranked
Basis
Provisional lane · 0 vs 0 weighted rows
Reading
Not comparable

Instruction following

Not comparable
Claude Opus 5.5
Not ranked
Mercury 2.5
77.7
#56/124
Basis
Provisional lane · 0 vs 1 weighted rows
Reading
Not comparable

Math

Not comparable
Claude Opus 5.5
Not ranked
Mercury 2.5
Not ranked
Basis
Provisional lane · 0 vs 0 weighted rows
Reading
Not comparable

Ranks count the models scored in each category’s lane, so the agentic, coding, and knowledge denominators (BenchAlign v5.6) differ from the provisional-lane categories. Unranked scores sit on the provisional lane’s scale but never name a winner. Like-for-like rows within 0.5 points read as a practical tie.

Supported evidence per lane · bars run 0–100Methodology

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 Opus 5.5
$0.014
Fits in one request
Mercury 2.5
$0.00012
Fits in one request

Mercury 2.5 has the lower modeled cost

Costs use the listed standard API rates.

Repository review

50K fresh input + 3K output tokens

Claude Opus 5.5
$0.26
Fits in one request
Mercury 2.5
$0.00245
Fits in one request

Mercury 2.5 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 Opus 5.5
$0.32
Fits in one request
Mercury 2.5
$0.0031
Fits in one request

Mercury 2.5 has the lower modeled cost

Costs use the listed standard API rates.

Cached input falls back to the list input rate only where a cached rate is unpublished

Specification differences

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

Reasoning profile

Claude Opus 5.5

Reasoning

Mercury 2.5

Reasoning

Weight access

Claude Opus 5.5

Proprietary

Mercury 2.5

Proprietary

License

Claude Opus 5.5

Proprietary

Mercury 2.5

Proprietary

Release date

Claude Opus 5.5

2026-09-22

Mercury 2.5

2026-09-08

If you already use one of these models

Deployment change
The models list different providers, so authentication, endpoint behavior, limits, and feature support may change.
Quality signal
The public evidence has no benchmark result shared by both models, so it does not support a quality verdict.
Workload cost
Repository review: $0.26 vs $0.00245. Cache-heavy agent loop: $0.32 vs $0.0031.
Context tradeoff
Claude Opus 5.5 has the larger documented window (1M).
Run the same representative tasks against both endpoints before changing production traffic.

Questions

Which is better, Claude Opus 5.5 or Mercury 2.5?

The public evidence has no benchmark result shared by both models, so it does not support a quality verdict. The page therefore keeps the decision tied to the specific documented workload.

Which is better for coding, Claude Opus 5.5 or Mercury 2.5?

Claude Opus 5.5 scores higher for coding on the public lane, 87.1 to 20.3. Mercury 2.5 is scored on Estimated evidence for coding, so the reading is directional rather than like-for-like. BenchLM does not name a winner for coding from a directional reading; read the shared benchmark rows directly and test the models on the same task set.

Which is better for agentic tasks, Claude Opus 5.5 or Mercury 2.5?

Claude Opus 5.5 leads the public agentic tasks lane, 88.8 to 12.4, with Supported evidence for both models and non-overlapping 90% intervals.

Which costs less, Claude Opus 5.5 or Mercury 2.5?

For the stated presets, chat costs $0.014 on Claude Opus 5.5 and $0.00012 on Mercury 2.5; repository review costs $0.26 and $0.00245; the cache-heavy agent loop costs $0.32 and $0.0031. Costs use the listed standard API rates.

Which has the larger context window, Claude Opus 5.5 or Mercury 2.5?

Claude Opus 5.5 has the larger documented context window: 1M, compared with 260K.

Benchmark evidence

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

Browse raw public benchmark evidence53 rows

Agentic

  • Terminal-Bench 4.0

    Claude Opus 5.566.40%
    Source
    Mercury 2.5—

    Not directly comparable

  • Terminal-Bench-Science 0.1

    Claude Opus 5.558.7%
    Source
    Mercury 2.5—

    Not directly comparable

  • AutomationBench

    Claude Opus 5.540.0%
    Source
    Mercury 2.5—

    Not directly comparable

  • HLE w/ tools

    Claude Opus 5.567.7%
    Source
    Mercury 2.5—

    Not directly comparable

  • OSWorld 2.0

    Claude Opus 5.548.7%
    Source
    Mercury 2.5—

    Not directly comparable

  • LAB all-pass (Harvey held-out)

    Claude Opus 5.58.3%
    Source
    Mercury 2.5—

    Not directly comparable

  • LAB criterion-pass (Harvey held-out)

    Claude Opus 5.591.2%
    Source
    Mercury 2.5—

    Not directly comparable

  • Toolathlon-Verified

    Claude Opus 5.577.8%
    Source
    Mercury 2.5—

    Not directly comparable

  • Toolathlon Verified Pass@3

    Claude Opus 5.582.4%
    Source
    Mercury 2.5—

    Not directly comparable

  • Toolathlon Verified Pass³

    Claude Opus 5.572.2%
    Source
    Mercury 2.5—

    Not directly comparable

  • Toolathlon Verified avg. turns

    Claude Opus 5.526.9 turns
    Source
    Mercury 2.5—

    Not directly comparable

  • τ³-bench results

    Claude Opus 5.5—
    Mercury 2.596.0%
    Source

    Not directly comparable

  • DeepSearchQA

    Claude Opus 5.5—
    Mercury 2.534.0%
    Source

    Not directly comparable

  • Terminal-Bench 2.1 (Vals)

    Claude Opus 5.5—
    Mercury 2.534.1%
    Source

    Not directly comparable

Coding

  • FrontierCode 1.1 Main

    Claude Opus 5.554.4%
    Source
    Mercury 2.5—

    Not directly comparable

  • cursorBench40

    Claude Opus 5.557.8%
    Source
    Mercury 2.5—

    Not directly comparable

  • SWE-bench Pro

    Claude Opus 5.589.9%
    Source
    Mercury 2.5—

    Not directly comparable

  • SWE Multilingual

    Claude Opus 5.593.9%
    Source
    Mercury 2.5—

    Not directly comparable

  • SWE Multimodal

    Claude Opus 5.561.4%
    Source
    Mercury 2.5—

    Not directly comparable

  • DeepSWE

    Claude Opus 5.574.2%
    Source
    Mercury 2.5—

    Not directly comparable

  • FrontierCode 1.1 Extended

    Claude Opus 5.563.6%
    Source
    Mercury 2.5—

    Not directly comparable

  • FrontierSWE v2

    Claude Opus 5.562.3%
    Source
    Mercury 2.5—

    Not directly comparable

  • ProgramBench

    Claude Opus 5.591.2%
    Source
    Mercury 2.5—

    Not directly comparable

  • SciCode

    Claude Opus 5.5—
    Mercury 2.538%
    Source

    Not directly comparable

Multimodal

  • Chartography (tools)

    Claude Opus 5.589.0%
    Source
    Mercury 2.5—

    Not directly comparable

  • Chartography (no tools)

    Claude Opus 5.564.4%
    Source
    Mercury 2.5—

    Not directly comparable

  • BenchCAD Vision2Code (no tools)

    Claude Opus 5.50.730
    Source
    Mercury 2.5—

    Not directly comparable

  • BenchCAD Vision2Code (tools)

    Claude Opus 5.50.962
    Source
    Mercury 2.5—

    Not directly comparable

  • Biomedical image analysis

    Claude Opus 5.571.4%
    Source
    Mercury 2.5—

    Not directly comparable

  • OfficeQA

    Claude Opus 5.578.9%
    Source
    Mercury 2.5—

    Not directly comparable

  • OfficeQA Pro

    Claude Opus 5.567.7%
    Source
    Mercury 2.5—

    Not directly comparable

Knowledge

  • HLE w/o tools

    Claude Opus 5.564.4%
    Source
    Mercury 2.5—

    Not directly comparable

  • HealthBench (raw)

    Claude Opus 5.568.1%
    Source
    Mercury 2.5—

    Not directly comparable

  • HealthBench (length-adjusted)

    Claude Opus 5.560.6%
    Source
    Mercury 2.5—

    Not directly comparable

  • HealthBench Professional

    Claude Opus 5.565.6%
    Source
    Mercury 2.5—

    Not directly comparable

  • HealthBench Professional (raw)

    Claude Opus 5.577.1%
    Source
    Mercury 2.5—

    Not directly comparable

  • BioMysteryBench (human-solvable)

    Claude Opus 5.589.3%
    Source
    Mercury 2.5—

    Not directly comparable

  • BioMysteryBench (human-difficult)

    Claude Opus 5.550.0%
    Source
    Mercury 2.5—

    Not directly comparable

  • SpatialBench Verified

    Claude Opus 5.572.0%
    Source
    Mercury 2.5—

    Not directly comparable

  • SingleCellBench

    Claude Opus 5.561.2%
    Source
    Mercury 2.5—

    Not directly comparable

  • Morphology-to-molecule matching

    Claude Opus 5.534.0%
    Source
    Mercury 2.5—

    Not directly comparable

  • Medicinal chemistry

    Claude Opus 5.563.5%
    Source
    Mercury 2.5—

    Not directly comparable

  • Protein Design

    Claude Opus 5.560.2%
    Source
    Mercury 2.5—

    Not directly comparable

  • Protein Design library ranking

    Claude Opus 5.556.0%
    Source
    Mercury 2.5—

    Not directly comparable

  • De novo protein-binder design

    Claude Opus 5.582.6%
    Source
    Mercury 2.5—

    Not directly comparable

  • Protocols (troubleshooting)

    Claude Opus 5.573.7%
    Source
    Mercury 2.5—

    Not directly comparable

  • Protocols (understanding)

    Claude Opus 5.569.0%
    Source
    Mercury 2.5—

    Not directly comparable

  • GPQA-D

    Claude Opus 5.5—
    Mercury 2.579.0%
    Source

    Not directly comparable

Multilingual

  • GMMLU

    Claude Opus 5.594.3%
    Source
    Mercury 2.5—

    Not directly comparable

  • MILU

    Claude Opus 5.593.1%
    Source
    Mercury 2.5—

    Not directly comparable

Instruction following

  • IFBench

    Claude Opus 5.5—
    Mercury 2.577%
    Source

    Not directly comparable

Math

  • ArXivMath Aug. 2026 (no tools)

    Claude Opus 5.591.2%
    Source
    Mercury 2.5—

    Not directly comparable

  • ArXivMath Aug. 2026 (tools)

    Claude Opus 5.596.9%
    Source
    Mercury 2.5—

    Not directly comparable

53 public results · 0 shared

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Last updated September 23, 2026