Mercury 2 vs o4 Mini
o4 Mini leads Mercury 2 on the Artificial Analysis Intelligence Index, 16.7 to 10.8, and Mercury 2 costs 5.9x less per output token ($0.75 vs $4.40 per million). Updated October 21, 2026; 33 benchmarks have a result for both.
Mercury 2 or o4 Mini: which to pick
Neither model has a coding score yet, so the two cannot be ranked on coding.
Pick Mercury 2 for output tokens 5.9x cheaper ($0.75 vs $4.40 per million) and work measured by WeirdML or AA Intelligence Index, where it leads.
- Shared results
- 33
- Mercury 2 only
- 9
- o4 Mini only
- 65
- Like-for-like categories
- 7 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
Neither has a coding score yet.
One side not measured
Intelligence
AA Intelligence Index
o4 Mini
o4 Mini leads, 16.7 against 10.8.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Mercury 2 has a AA Agentic Index result, 1.6.
Directional only
Reasoning
GPQA Diamond
No call
Only o4 Mini has a GPQA Diamond result, 74.5%.
Directional only
Math
AIME
No call
Only o4 Mini has a AIME result, 83.7%.
Directional only
Knowledge
MMLU Pro
No call
Only o4 Mini has a MMLU Pro result, 80.6%.
Directional only
Web design
Design Arena: websites
Mercury 2
Mercury 2 leads, 1036 against 985.
Same board, both measured
Long documents
Listed context window
o4 Mini
o4 Mini takes 200K tokens against 128K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Mercury 2
Mercury 2 $0.0006, o4 Mini $0.0033 per turn.
List prices
At a glance
- Coding index
- Mercury 2 not benchmarked, o4 Mini not benchmarked.
- Widest category
- Agentic work, 15.2 points apart on average over 1 shared benchmark.
- Widest single gap
- Long context reasoning (AA-LCR): Mercury 2 43.7% against o4 Mini 61.0%, 17.3 points apart on a 0 to 100 scale.
- Output price
- Mercury 2 $0.75 against o4 Mini $4.40 per million output tokens, 5.9x apart.
- Context window
- Mercury 2 takes 128K tokens, o4 Mini 200K.
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 | Mercury 2 | Bars | o4 Mini | Ties |
|---|---|---|---|---|
| Coding | 3 | 1 | ||
| Intelligence | 0 | 1 | ||
| Agentic work | 1 | 0 | ||
| Reasoning | 4 | 1 | ||
| Knowledge | 2 | 1 | ||
| Web design | 5 | 1 | ||
| General | 8 | 5 | ||
| All shared boards | 23 | 10 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index31
| Benchmark | Mercury 2 | o4 Mini | Leader |
|---|---|---|---|
| Aider polyglot | Not measured | 72.0% | Only o4 Mini measured |
| SWE-bench Verified | Not measured | 64.6% | Only o4 Mini measured |
| SWE-bench Multimodal | Not measured | 33.9% | Only o4 Mini measured |
| LMArena WebDev | 1171 | Not measured | Only Mercury 2 measured |
| AA Coding Index | 31.1 | Not measured | Only Mercury 2 measured |
| LiveCodeBench (Vals AI) | Not measured | 82.2% | Only o4 Mini measured |
| LiveCodeBench (Artificial Analysis run) | Not measured | 85.9% | Only o4 Mini measured |
| SciCode | 37.7% | Not measured | Only Mercury 2 measured |
| Terminal-Bench Hard (Artificial Analysis run) | 26.5% | 15.2% | Mercury 2 |
| GSO-Bench | Not measured | 3.6% | Only o4 Mini measured |
| WeirdML | 43.2% | 52.6% | o4 Mini |
| ALE-Bench | 785.6 | Not measured | Only Mercury 2 measured |
| LMArena Text: coding | 1390 | 1368 | Mercury 2 |
| LMArena Text: software and IT | 1385 | 1367 | Mercury 2 |
| LMArena WebDev: React | 1160 | Not measured | Only Mercury 2 measured |
| LMArena WebDev: HTML | 1199 | Not measured | Only Mercury 2 measured |
| SciCode | Not measured | 10.8% | Only o4 Mini measured |
| Neither model has a result on the other 22 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index01
| Benchmark | Mercury 2 | o4 Mini | Leader |
|---|---|---|---|
| AA Intelligence Index | 10.8 | 16.7 | o4 Mini |
| Epoch Capabilities Index | Not measured | 145.5 | Only o4 Mini measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Mercury 2 | o4 Mini | Leader |
|---|---|---|---|
| AA Agentic Index | 1.6 | Not measured | Only Mercury 2 measured |
| τ²-Bench Telecom | 70.8% | 55.6% | Mercury 2 |
| METR time horizons | Not measured | 63.9% | Only o4 Mini measured |
| Berkeley Function Calling Leaderboard (BFCL) | Not measured | 53.2% | Only o4 Mini measured |
| Neither model has a result on the other 37 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index41
| Benchmark | Mercury 2 | o4 Mini | Leader |
|---|---|---|---|
| GPQA Diamond | Not measured | 74.5% | Only o4 Mini measured |
| MMMU Pro (Vals AI) | Not measured | 79.7% | Only o4 Mini measured |
| GPQA Diamond (Artificial Analysis run) | 77.0% | 78.4% | o4 Mini |
| Humanity's Last Exam (Artificial Analysis run) | 17.1% | 16.5% | Mercury 2 |
| GPQA Diamond (Epoch AI run) | Not measured | 79.6% | Only o4 Mini measured |
| ARC-AGI | Not measured | 58.7% | Only o4 Mini measured |
| ARC-AGI-2 | Not measured | 6.1% | Only o4 Mini measured |
| SimpleBench | Not measured | 38.7% | Only o4 Mini measured |
| Chess puzzles | Not measured | 22.0% | Only o4 Mini measured |
| Mystery game puzzles | Not measured | 5.0% | Only o4 Mini measured |
| VPCT | Not measured | 57.5% | Only o4 Mini measured |
| LMArena Text: hard prompts | 1362 | 1351 | Mercury 2 |
| LMArena Text: expert | 1358 | 1343 | Mercury 2 |
| LMArena Text: hard prompts in English | 1374 | 1366 | Mercury 2 |
| LMArena Vision: diagrams | Not measured | 1197 | Only o4 Mini measured |
| LMArena Vision: homework | Not measured | 1234 | Only o4 Mini measured |
| Kagi LLM Benchmark | Not measured | 67.6% | Only o4 Mini measured |
| Neither model has a result on the other 5 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index11 boards, none shared
| Benchmark | Mercury 2 | o4 Mini | Leader |
|---|---|---|---|
| AIME | Not measured | 83.7% | Only o4 Mini measured |
| MATH 500 (Vals AI) | Not measured | 94.2% | Only o4 Mini measured |
| MGSM (Vals AI) | Not measured | 93.4% | Only o4 Mini measured |
| AA Math Index | Not measured | 90.7 | Only o4 Mini measured |
| AIME 2025 (Artificial Analysis run) | Not measured | 90.7% | Only o4 Mini measured |
| OTIS Mock AIME | Not measured | 81.7% | Only o4 Mini measured |
| FrontierMath, tiers 1 to 3 | Not measured | 36.1% | Only o4 Mini measured |
| FrontierMath, tier 4 | Not measured | 4.9% | Only o4 Mini measured |
| MATH level 5 | Not measured | 97.8% | Only o4 Mini measured |
| LMArena Text: math | Not measured | 1389 | Only o4 Mini measured |
| LMArena Text: mathematical work | Not measured | 1379 | Only o4 Mini measured |
| Neither model has a result on the other 2 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index21
| Benchmark | Mercury 2 | o4 Mini | Leader |
|---|---|---|---|
| MMLU Pro | Not measured | 80.6% | Only o4 Mini measured |
| LegalBench (Vals AI) | Not measured | 79.2% | Only o4 Mini measured |
| CorpFin (Vals AI) | Not measured | 59.0% | Only o4 Mini measured |
| TaxEval (Vals AI) | Not measured | 74.8% | Only o4 Mini measured |
| MortgageTax (Vals AI) | Not measured | 64.8% | Only o4 Mini measured |
| MedQA (Vals AI) | Not measured | 96.0% | Only o4 Mini measured |
| MedCode (Vals AI) | Not measured | 33.8% | Only o4 Mini measured |
| MMLU Pro (Artificial Analysis run) | Not measured | 83.2% | Only o4 Mini measured |
| SimpleQA Verified | Not measured | 19.6% | Only o4 Mini measured |
| GeoBench | Not measured | 64.0% | Only o4 Mini measured |
| LMArena Text: science | 1343 | 1354 | o4 Mini |
| LMArena Text: medicine and healthcare | 1363 | 1361 | Mercury 2 |
| LMArena Text: legal and government | Not measured | 1350 | Only o4 Mini measured |
| LMArena Text: business and finance | 1349 | 1325 | Mercury 2 |
| FACTS Benchmark Suite | Not measured | 28.1% | Only o4 Mini measured |
| Neither model has a result on the other 3 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index51
| Benchmark | Mercury 2 | o4 Mini | Leader |
|---|---|---|---|
| Design Arena: websites | 1036 | 985 | Mercury 2 |
| Design Arena: UI components | 998 | 983 | Mercury 2 |
| Design Arena: game dev | 985 | 1003 | o4 Mini |
| Design Arena: data viz | 1009 | 990 | Mercury 2 |
| Design Arena: 3D | 983 | 854 | Mercury 2 |
| Design Arena: all code categories | 1022 | 976 | Mercury 2 |
| Design Arena: SVG | 998 | Not measured | Only Mercury 2 measured |
| Design Arena: ASCII art | 988 | Not measured | Only Mercury 2 measured |
| Neither model has a result on the other 1 board here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index85
| Benchmark | Mercury 2 | o4 Mini | Leader |
|---|---|---|---|
| SAGE (Vals AI) | Not measured | 41.1% | Only o4 Mini measured |
| MedScribe (Vals AI) | Not measured | 69.1% | Only o4 Mini measured |
| IFBench | 69.8% | 68.7% | Mercury 2 |
| Long context reasoning (AA-LCR) | 43.7% | 61.0% | o4 Mini |
| DTBench | Not measured | 77.6% | Only o4 Mini measured |
| LMCA | Not measured | 26.5% | Only o4 Mini measured |
| Fiction.LiveBench | Not measured | 77.8% | Only o4 Mini measured |
| Creative writing (Lech Mazur) | Not measured | 75.0% | Only o4 Mini measured |
| LMArena Text | 1354 | 1353 | Mercury 2 |
| LMArena Text: instruction following | 1328 | 1320 | Mercury 2 |
| LMArena Text: creative writing | 1286 | 1294 | o4 Mini |
| LMArena Vision | Not measured | 1194 | Only o4 Mini measured |
| LMArena Text: English | 1378 | 1367 | Mercury 2 |
| LMArena Text: non-English | 1330 | 1337 | o4 Mini |
| LMArena Text: Chinese | 1414 | 1354 | Mercury 2 |
| LMArena Text: German | Not measured | 1336 | Only o4 Mini measured |
| LMArena Text: Japanese | Not measured | 1308 | Only o4 Mini measured |
| LMArena Text: Korean | Not measured | 1312 | Only o4 Mini measured |
| LMArena Text: French | Not measured | 1364 | Only o4 Mini measured |
| LMArena Text: Spanish | Not measured | 1346 | Only o4 Mini measured |
| LMArena Text: Russian | 1304 | 1334 | o4 Mini |
| LMArena Text: Polish | Not measured | 1358 | Only o4 Mini measured |
| LMArena Text: multi-turn | 1357 | 1350 | Mercury 2 |
| LMArena Text: longer queries | 1329 | 1315 | Mercury 2 |
| LMArena Text: writing and language | 1300 | 1316 | o4 Mini |
| LMArena Text: entertainment and media | 1314 | 1308 | Mercury 2 |
| LMArena Vision: English | Not measured | 1200 | Only o4 Mini measured |
| LMArena Vision: Chinese | Not measured | 1218 | Only o4 Mini measured |
| LMArena Vision: reading text | Not measured | 1197 | Only o4 Mini measured |
| LMArena Vision: humor | Not measured | 1199 | Only o4 Mini measured |
| LMArena Vision: captioning | Not measured | 1204 | Only o4 Mini measured |
| LMArena Vision: recognizing things | Not measured | 1218 | Only o4 Mini measured |
| LMArena Vision: creative writing | Not measured | 1166 | Only o4 Mini measured |
| Neither model has a result on the other 13 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Mercury 2 | o4 Mini | 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 costs less
Repository review
50K input + 3K output tokens
Mercury 2 costs less
Agent loop
200K input + 10K output tokens
Mercury 2 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 | Inception Mercury 2 | OpenAI o4 Mini |
|---|---|---|
| Maker | Inception | OpenAI |
| Weights | No public weights listed | No public weights listed |
| Released | March 4, 2026 | April 16, 2025 |
| Context window | 128K | 200K |
| Input $/Mtok | $0.25 | $1.10 |
| Output $/Mtok | $0.75 | $4.40 |
| Coding index | Not benchmarked | Not benchmarked |
| Independent measurements behind it | 1 | 0 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Mercury 2 better than o4 Mini for coding?
Neither model has a coding score yet, so the two cannot be ranked on coding. Pick Mercury 2 for output tokens 5.9x cheaper ($0.75 vs $4.40 per million) and work measured by WeirdML or AA Intelligence Index, where it leads.
Which is cheaper, Mercury 2 or o4 Mini?
Mercury 2 costs $0.25 per million input tokens and $0.75 per million output tokens; o4 Mini costs $1.10 and $4.40. Cost per solved task is known for neither of them.
Which has the bigger context window, Mercury 2 or o4 Mini?
o4 Mini, with 200K tokens against 128K.
How many benchmarks is the Mercury 2 vs o4 Mini comparison based on?
33 benchmarks have a result for both models as of October 21, 2026. Mercury 2's coding index rests on 1 independent benchmark and o4 Mini's on 0. Where only one model has a result, the page says so instead of naming a winner.