Claude Opus 4.1 vs Mercury 2.5
Claude Opus 4.1 leads Mercury 2.5 on the Artificial Analysis Intelligence Index, 22.8 to 12.3, and Mercury 2.5 costs 500.0x less per output token ($0.15 vs $75.00 per million). Updated October 22, 2026; 4 benchmarks have a result for both.
Claude Opus 4.1 or Mercury 2.5: which to pick
Only Mercury 2.5 has a coding score, 1.6 on the Vibe Coding Index; Claude Opus 4.1 has none, so the two cannot be ranked on coding.
Pick Claude Opus 4.1 for work measured by AA Intelligence Index or LegalBench (Vals AI), where it leads.
- Shared results
- 4
- Claude Opus 4.1 only
- 69
- Mercury 2.5 only
- 18
- Like-for-like categories
- 3 of 9
Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.
Which one for your work
Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.
Coding
Vibe Coding Index, six public coding benchmarks
No call
Only Mercury 2.5 has a coding score, so no call is made.
One side not measured
Intelligence
AA Intelligence Index
Claude Opus 4.1
Claude Opus 4.1 leads, 22.8 against 12.3.
Same board, both measured
Reasoning
GPQA Diamond
No call
Only Claude Opus 4.1 has a GPQA Diamond result, 76.3%.
Directional only
Math
AIME
No call
Only Claude Opus 4.1 has a AIME result, 78.2%.
Directional only
Knowledge
MMLU Pro
No call
Only Claude Opus 4.1 has a MMLU Pro result, 87.9%.
Directional only
Web design
Design Arena: websites
No call
Only Claude Opus 4.1 has a Design Arena: websites result, 1176.
Directional only
Long documents
Listed context window
Mercury 2.5
Mercury 2.5 takes 260K tokens against 200K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Mercury 2.5
Claude Opus 4.1 $0.052, Mercury 2.5 $0.0001 per turn.
List prices
At a glance
- Coding index
- Claude Opus 4.1 not benchmarked, Mercury 2.5 1.6 from 2 benchmarks.
- Widest category
- General, 18.8 points apart on average over 1 shared benchmark.
- Widest single gap
- MedScribe (Vals AI): Claude Opus 4.1 73.9% against Mercury 2.5 55.1%, 18.8 points apart on a 0 to 100 scale.
- Output price
- Claude Opus 4.1 $75.00 against Mercury 2.5 $0.15 per million output tokens, 500.0x apart.
- Context window
- Claude Opus 4.1 takes 200K tokens, Mercury 2.5 260K.
Benchmark by benchmark
First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.
| Category | Claude Opus 4.1 | Bars | Mercury 2.5 | Ties |
|---|---|---|---|---|
| Intelligence | 1 | 0 | ||
| Knowledge | 2 | 0 | ||
| General | 1 | 0 | ||
| All shared boards | 4 | 0 |
CodingDirectional onlySix of these boards feed the Vibe Coding Index18 boards, none shared
| Benchmark | Claude Opus 4.1 | Mercury 2.5 | Leader |
|---|---|---|---|
| LMArena WebDev | 1390 | Not measured | Only Claude Opus 4.1 measured |
| LiveCodeBench (Vals AI) | 66.5% | Not measured | Only Claude Opus 4.1 measured |
| Terminal-Bench 4 (Vals AI) | Not measured | 0.0% | Only Mercury 2.5 measured |
| Vibe Code Bench (Vals AI) | Not measured | 3.7% | Only Mercury 2.5 measured |
| Code migration (Vals AI) | Not measured | 4.5% | Only Mercury 2.5 measured |
| IOI (Vals AI) | Not measured | 2.4% | Only Mercury 2.5 measured |
| Terminal-Bench 2.1 (Vals AI) | Not measured | 34.5% | Only Mercury 2.5 measured |
| SkillsBench (Vals AI) | Not measured | 18.1% | Only Mercury 2.5 measured |
| CyberBench (Vals AI) | Not measured | 45.5% | Only Mercury 2.5 measured |
| SciCode | Not measured | 38.5% | Only Mercury 2.5 measured |
| Terminal-Bench | 38.0% | Not measured | Only Claude Opus 4.1 measured |
| WeirdML | 45.9% | Not measured | Only Claude Opus 4.1 measured |
| Cybench | 42.0% | Not measured | Only Claude Opus 4.1 measured |
| ALE-Bench | Not measured | 301.6 | Only Mercury 2.5 measured |
| LMArena Text: coding | 1479 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: software and IT | 1456 | Not measured | Only Claude Opus 4.1 measured |
| LMArena WebDev: HTML | 1399 | Not measured | Only Claude Opus 4.1 measured |
| SciCode | 4.6% | Not measured | Only Claude Opus 4.1 measured |
| Neither model has a result on the other 21 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Opus 4.1 | Mercury 2.5 | Leader |
|---|---|---|---|
| AA Intelligence Index | 22.8 | 12.3 | Claude Opus 4.1 |
| Epoch Capabilities Index | 144.1 | Not measured | Only Claude Opus 4.1 measured |
Agentic workDirectional onlyPublic boards, shown as published, kept out of the index8 boards, none shared
| Benchmark | Claude Opus 4.1 | Mercury 2.5 | Leader |
|---|---|---|---|
| Finance Agent (Vals AI) | Not measured | 18.9% | Only Mercury 2.5 measured |
| Tax Agent Bench (Vals AI) | Not measured | 2.5% | Only Mercury 2.5 measured |
| Legal Research Bench (Vals AI) | Not measured | 4.3% | Only Mercury 2.5 measured |
| Excel Modeling Benchmark (Vals AI) | Not measured | 8.8% | Only Mercury 2.5 measured |
| Terminal-Bench-Science (Vals AI) | Not measured | 0.0% | Only Mercury 2.5 measured |
| METR time horizons | 66.8% | Not measured | Only Claude Opus 4.1 measured |
| GDPval | 43.6% | Not measured | Only Claude Opus 4.1 measured |
| DeepResearch Bench | 48.3% | Not measured | Only Claude Opus 4.1 measured |
| Neither model has a result on the other 33 boards here | |||
ReasoningDirectional onlyPublic boards, shown as published, kept out of the index11 boards, none shared
| Benchmark | Claude Opus 4.1 | Mercury 2.5 | Leader |
|---|---|---|---|
| GPQA Diamond | 76.3% | Not measured | Only Claude Opus 4.1 measured |
| MMMU Pro (Vals AI) | 77.5% | Not measured | Only Claude Opus 4.1 measured |
| Humanity's Last Exam (Artificial Analysis run) | Not measured | 11.8% | Only Mercury 2.5 measured |
| GPQA Diamond (Epoch AI run) | 77.3% | Not measured | Only Claude Opus 4.1 measured |
| SimpleBench | 60.0% | Not measured | Only Claude Opus 4.1 measured |
| Mystery game puzzles | 21.0% | Not measured | Only Claude Opus 4.1 measured |
| EBR-bench | 7.9% | Not measured | Only Claude Opus 4.1 measured |
| VPCT | 35.0% | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: hard prompts | 1442 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: expert | 1438 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: hard prompts in English | 1451 | Not measured | Only Claude Opus 4.1 measured |
| Neither model has a result on the other 11 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index9 boards, none shared
| Benchmark | Claude Opus 4.1 | Mercury 2.5 | Leader |
|---|---|---|---|
| AIME | 78.2% | Not measured | Only Claude Opus 4.1 measured |
| MATH 500 (Vals AI) | 95.4% | Not measured | Only Claude Opus 4.1 measured |
| MGSM (Vals AI) | 94.4% | Not measured | Only Claude Opus 4.1 measured |
| OTIS Mock AIME | 68.9% | Not measured | Only Claude Opus 4.1 measured |
| FrontierMath, tiers 1 to 3 | 12.6% | Not measured | Only Claude Opus 4.1 measured |
| FrontierMath, tier 4 | 2.4% | Not measured | Only Claude Opus 4.1 measured |
| ProofBench | Not measured | 3.0% | Only Mercury 2.5 measured |
| LMArena Text: math | 1431 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: mathematical work | 1434 | Not measured | Only Claude Opus 4.1 measured |
| Neither model has a result on the other 4 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Claude Opus 4.1 | Mercury 2.5 | Leader |
|---|---|---|---|
| MMLU Pro | 87.9% | Not measured | Only Claude Opus 4.1 measured |
| LegalBench (Vals AI) | 83.5% | 83.1% | Claude Opus 4.1 |
| TaxEval (Vals AI) | 73.7% | Not measured | Only Claude Opus 4.1 measured |
| MortgageTax (Vals AI) | 61.1% | Not measured | Only Claude Opus 4.1 measured |
| MedQA (Vals AI) | 93.6% | Not measured | Only Claude Opus 4.1 measured |
| MedCode (Vals AI) | 47.2% | 31.3% | Claude Opus 4.1 |
| LMArena Text: science | 1422 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: medicine and healthcare | 1416 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: legal and government | 1421 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: business and finance | 1406 | Not measured | Only Claude Opus 4.1 measured |
| FACTS Benchmark Suite | 40.4% | Not measured | Only Claude Opus 4.1 measured |
| Neither model has a result on the other 7 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index8 boards, none shared
| Benchmark | Claude Opus 4.1 | Mercury 2.5 | Leader |
|---|---|---|---|
| Design Arena: websites | 1176 | Not measured | Only Claude Opus 4.1 measured |
| Design Arena: UI components | 1162 | Not measured | Only Claude Opus 4.1 measured |
| Design Arena: game dev | 1171 | Not measured | Only Claude Opus 4.1 measured |
| Design Arena: data viz | 1166 | Not measured | Only Claude Opus 4.1 measured |
| Design Arena: 3D | 1152 | Not measured | Only Claude Opus 4.1 measured |
| Design Arena: all code categories | 1170 | Not measured | Only Claude Opus 4.1 measured |
| Design Arena: SVG | 1152 | Not measured | Only Claude Opus 4.1 measured |
| Design Arena: ASCII art | 1167 | Not measured | Only Claude Opus 4.1 measured |
| Neither model has a result on the other 1 board here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Opus 4.1 | Mercury 2.5 | Leader |
|---|---|---|---|
| Public Benefits Bench (Vals AI) | Not measured | 45.3% | Only Mercury 2.5 measured |
| SAGE (Vals AI) | 31.4% | Not measured | Only Claude Opus 4.1 measured |
| MedScribe (Vals AI) | 73.9% | 55.1% | Claude Opus 4.1 |
| Long context reasoning (AA-LCR) | Not measured | 71.7% | Only Mercury 2.5 measured |
| DTBench | 80.0% | Not measured | Only Claude Opus 4.1 measured |
| LMCA | 37.1% | Not measured | Only Claude Opus 4.1 measured |
| Creative writing (Lech Mazur) | 84.7% | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text | 1419 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: instruction following | 1435 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: creative writing | 1412 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: English | 1433 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: non-English | 1405 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: Chinese | 1427 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: German | 1413 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: Japanese | 1377 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: Korean | 1381 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: French | 1433 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: Spanish | 1448 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: Russian | 1422 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: Polish | 1413 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: multi-turn | 1444 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: longer queries | 1455 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: writing and language | 1418 | Not measured | Only Claude Opus 4.1 measured |
| LMArena Text: entertainment and media | 1398 | Not measured | Only Claude Opus 4.1 measured |
| Neither model has a result on the other 22 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Opus 4.1 | Mercury 2.5 | Leader |
|---|---|---|---|
| Neither model has a result on 5 boards here | |||
What each workload costs
Three fixed token mixes at each model's listed price, so per-token rates become a bill.
Chat turn
1K input + 500 output tokens
Mercury 2.5 costs less
Repository review
50K input + 3K output tokens
Mercury 2.5 costs less
Agent loop
200K input + 10K output tokens
Mercury 2.5 costs less
Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.
Specification differences
The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.
| Specification | Anthropic Claude Opus 4.1 | Inception Mercury 2.5 |
|---|---|---|
| Maker | Anthropic | Inception |
| Weights | No public weights listed | No public weights listed |
| Released | August 5, 2025 | September 8, 2026 |
| Context window | 200K | 260K |
| Input $/Mtok | $15.00 | $0.04 |
| Output $/Mtok | $75.00 | $0.15 |
| Coding index | Not benchmarked | 1.6 |
| Independent measurements behind it | 1 | 2 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Opus 4.1 better than Mercury 2.5 for coding?
Only Mercury 2.5 has a coding score, 1.6 on the Vibe Coding Index; Claude Opus 4.1 has none, so the two cannot be ranked on coding. Pick Claude Opus 4.1 for work measured by AA Intelligence Index or LegalBench (Vals AI), where it leads.
Which is cheaper, Claude Opus 4.1 or Mercury 2.5?
Claude Opus 4.1 costs $15.00 per million input tokens and $75.00 per million output tokens; Mercury 2.5 costs $0.04 and $0.15. Cost per solved task is known for neither of them.
Which has the bigger context window, Claude Opus 4.1 or Mercury 2.5?
Mercury 2.5, with 260K tokens against 200K.
How many benchmarks is the Claude Opus 4.1 vs Mercury 2.5 comparison based on?
4 benchmarks have a result for both models as of October 22, 2026. Claude Opus 4.1's coding index rests on 1 independent benchmark and Mercury 2.5's on 2. Where only one model has a result, the page says so instead of naming a winner.