Gemini 3.1 Flash Lite Preview vs Mercury 2.5
Gemini 3.1 Flash Lite Preview leads Mercury 2.5 on coding, 22.7 to 1.6 on the Vibe Coding Index, and Mercury 2.5 costs 10.0x less per output token ($0.15 vs $1.50 per million). Updated October 22, 2026; 12 benchmarks have a result for both.
Gemini 3.1 Flash Lite Preview or Mercury 2.5: which to pick
Pick Gemini 3.1 Flash Lite Preview for coding: it scores 22.7 on the Vibe Coding Index against 1.6 for Mercury 2.5.
Pick Mercury 2.5 for output tokens 10.0x cheaper ($0.15 vs $1.50 per million) and work measured by Vibe Code Bench (Vals AI) or Terminal-Bench 2.1 (Vals AI), where it leads.
- Shared results
- 12
- Gemini 3.1 Flash Lite Preview only
- 67
- Mercury 2.5 only
- 10
- Like-for-like categories
- 5 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
Gemini 3.1 Flash Lite Preview
Gemini 3.1 Flash Lite Preview scores 22.7 against 1.6.
3 and 2 benchmarks behind the scores
Intelligence
AA Intelligence Index
Gemini 3.1 Flash Lite Preview
Gemini 3.1 Flash Lite Preview leads, 15.6 against 12.3.
Same board, both measured
Agentic work
AA Agentic Index
No call
Only Gemini 3.1 Flash Lite Preview has a AA Agentic Index result, 1.6.
Directional only
Reasoning
GPQA Diamond
No call
Only Gemini 3.1 Flash Lite Preview has a GPQA Diamond result, 81.1%.
Directional only
Math
AIME
No call
Only Gemini 3.1 Flash Lite Preview has a AIME result, 83.3%.
Directional only
Knowledge
MMLU Pro
No call
Only Gemini 3.1 Flash Lite Preview has a MMLU Pro result, 86.2%.
Directional only
Web design
Design Arena: websites
No call
Only Gemini 3.1 Flash Lite Preview has a Design Arena: websites result, 1082.
Directional only
Long documents
Listed context window
Gemini 3.1 Flash Lite Preview
Gemini 3.1 Flash Lite Preview takes 1.05M tokens against 260K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Mercury 2.5
Gemini 3.1 Flash Lite Preview $0.0010, Mercury 2.5 $0.0001 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Gemini 3.1 Flash Lite Preview has the number, $0.18.
Directional only
At a glance
- Coding index
- Gemini 3.1 Flash Lite Preview 22.7 from 3 benchmarks, Mercury 2.5 1.6 from 2 benchmarks.
- Widest category
- General, 8.8 points apart on average over 1 shared benchmark.
- Widest single gap
- ALE-Bench: Gemini 3.1 Flash Lite Preview 797.7 against Mercury 2.5 301.6, 16.5 points apart on a 0 to 100 scale.
- Output price
- Gemini 3.1 Flash Lite Preview $1.50 against Mercury 2.5 $0.15 per million output tokens, 10.0x apart.
- Context window
- Gemini 3.1 Flash Lite Preview takes 1.05M 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 | Gemini 3.1 Flash Lite Preview | Bars | Mercury 2.5 | Ties |
|---|---|---|---|---|
| Coding | 2 | 2 | ||
| Intelligence | 1 | 0 | ||
| Agentic work | 2 | 2 | ||
| Knowledge | 2 | 0 | ||
| General | 1 | 0 | ||
| All shared boards | 8 | 4 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index22
| Benchmark | Gemini 3.1 Flash Lite Preview | Mercury 2.5 | Leader |
|---|---|---|---|
| LMArena WebDev | 1257 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| AA Coding Index | 34.7 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LiveCodeBench (Vals AI) | 80.1% | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| SWE-bench Verified (Vals AI) | 62.8% | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| Terminal-Bench 4 (Vals AI) | Not measured | 0.0% | Only Mercury 2.5 measured |
| Vibe Code Bench (Vals AI) | 0.0% | 3.7% | Mercury 2.5 |
| Code migration (Vals AI) | 4.6% | 4.5% | Gemini 3.1 Flash Lite Preview |
| ProgramBench (Vals AI) | 0.0% | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| IOI (Vals AI) | Not measured | 2.4% | Only Mercury 2.5 measured |
| Terminal-Bench 2.1 (Vals AI) | 34.1% | 34.5% | Mercury 2.5 |
| 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 |
| ALE-Bench | 797.7 | 301.6 | Gemini 3.1 Flash Lite Preview |
| LMArena Text: coding | 1400 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: software and IT | 1413 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena WebDev: React | 1245 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena WebDev: HTML | 1276 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena WebDev: from an image | 1336 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| SciCode | 4.6% | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| Neither model has a result on the other 19 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Gemini 3.1 Flash Lite Preview | Mercury 2.5 | Leader |
|---|---|---|---|
| AA Intelligence Index | 15.6 | 12.3 | Gemini 3.1 Flash Lite Preview |
| Neither model has a result on the other 1 board here | |||
Agentic workLike-for-likePublic boards, shown as published, kept out of the index22
| Benchmark | Gemini 3.1 Flash Lite Preview | Mercury 2.5 | Leader |
|---|---|---|---|
| AA Agentic Index | 1.6 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| Finance Agent (Vals AI) | 30.0% | 18.9% | Gemini 3.1 Flash Lite Preview |
| Tax Agent Bench (Vals AI) | 3.1% | 2.5% | Gemini 3.1 Flash Lite Preview |
| Legal Research Bench (Vals AI) | 3.4% | 4.3% | Mercury 2.5 |
| Excel Modeling Benchmark (Vals AI) | 8.6% | 8.8% | Mercury 2.5 |
| Terminal-Bench-Science (Vals AI) | Not measured | 0.0% | Only Mercury 2.5 measured |
| Neither model has a result on the other 35 boards here | |||
ReasoningDirectional onlyPublic boards, shown as published, kept out of the index8 boards, none shared
| Benchmark | Gemini 3.1 Flash Lite Preview | Mercury 2.5 | Leader |
|---|---|---|---|
| GPQA Diamond | 81.1% | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| MMMU Pro (Vals AI) | 82.5% | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| Humanity's Last Exam (Artificial Analysis run) | Not measured | 11.8% | Only Mercury 2.5 measured |
| LMArena Text: hard prompts | 1407 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: expert | 1398 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: hard prompts in English | 1403 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Vision: diagrams | 1242 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Vision: homework | 1271 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| Neither model has a result on the other 14 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index4 boards, none shared
| Benchmark | Gemini 3.1 Flash Lite Preview | Mercury 2.5 | Leader |
|---|---|---|---|
| AIME | 83.3% | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| ProofBench | Not measured | 3.0% | Only Mercury 2.5 measured |
| LMArena Text: math | 1428 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: mathematical work | 1417 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| Neither model has a result on the other 9 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Gemini 3.1 Flash Lite Preview | Mercury 2.5 | Leader |
|---|---|---|---|
| MMLU Pro | 86.2% | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LegalBench (Vals AI) | 83.8% | 83.1% | Gemini 3.1 Flash Lite Preview |
| CaseLaw (Vals AI) | 55.0% | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| CorpFin (Vals AI) | 59.4% | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| TaxEval (Vals AI) | 71.8% | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| MortgageTax (Vals AI) | 68.0% | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| MedCode (Vals AI) | 47.6% | 31.3% | Gemini 3.1 Flash Lite Preview |
| LMArena Text: science | 1425 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: medicine and healthcare | 1428 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: legal and government | 1418 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: business and finance | 1389 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| FACTS Benchmark Suite | 51.4% | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| Neither model has a result on the other 6 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index8 boards, none shared
| Benchmark | Gemini 3.1 Flash Lite Preview | Mercury 2.5 | Leader |
|---|---|---|---|
| Design Arena: websites | 1082 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| Design Arena: UI components | 1069 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| Design Arena: game dev | 1029 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| Design Arena: data viz | 1045 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| Design Arena: 3D | 1047 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| Design Arena: all code categories | 1072 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| Design Arena: SVG | 1052 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| Design Arena: ASCII art | 1167 | Not measured | Only Gemini 3.1 Flash Lite Preview 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 | Gemini 3.1 Flash Lite Preview | Mercury 2.5 | Leader |
|---|---|---|---|
| Public Benefits Bench (Vals AI) | Not measured | 45.3% | Only Mercury 2.5 measured |
| SAGE (Vals AI) | 49.5% | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| MedScribe (Vals AI) | 63.9% | 55.1% | Gemini 3.1 Flash Lite Preview |
| Vals Multimodal Index | 41.4% | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| Long context reasoning (AA-LCR) | Not measured | 71.7% | Only Mercury 2.5 measured |
| LMArena Text | 1416 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: instruction following | 1377 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: creative writing | 1401 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Vision | 1240 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: English | 1414 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: non-English | 1410 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: Chinese | 1460 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: German | 1430 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: Japanese | 1413 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: Korean | 1392 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: French | 1424 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: Spanish | 1421 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: Russian | 1420 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: Polish | 1443 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: multi-turn | 1417 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: longer queries | 1394 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: writing and language | 1408 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Text: entertainment and media | 1386 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Vision: English | 1232 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Vision: Chinese | 1278 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Vision: reading text | 1246 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Vision: humor | 1266 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Vision: captioning | 1259 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Vision: recognizing things | 1308 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| LMArena Vision: creative writing | 1248 | Not measured | Only Gemini 3.1 Flash Lite Preview measured |
| Neither model has a result on the other 16 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Gemini 3.1 Flash Lite Preview | 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 | Google Gemini 3.1 Flash Lite Preview | Inception Mercury 2.5 |
|---|---|---|
| Maker | Inception | |
| Weights | No public weights listed | No public weights listed |
| Released | March 3, 2026 | September 8, 2026 |
| Context window | 1.05M | 260K |
| Input $/Mtok | $0.25 | $0.04 |
| Output $/Mtok | $1.50 | $0.15 |
| Coding index | 22.7 | 1.6 |
| Independent measurements behind it | 3 | 2 |
| Cost per solved task | $0.18 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Gemini 3.1 Flash Lite Preview better than Mercury 2.5 for coding?
Pick Gemini 3.1 Flash Lite Preview for coding: it scores 22.7 on the Vibe Coding Index against 1.6 for Mercury 2.5. Pick Mercury 2.5 for output tokens 10.0x cheaper ($0.15 vs $1.50 per million) and work measured by Vibe Code Bench (Vals AI) or Terminal-Bench 2.1 (Vals AI), where it leads.
Which is cheaper, Gemini 3.1 Flash Lite Preview or Mercury 2.5?
Gemini 3.1 Flash Lite Preview costs $0.25 per million input tokens and $1.50 per million output tokens; Mercury 2.5 costs $0.04 and $0.15. Cost per solved task is known for Gemini 3.1 Flash Lite Preview only.
Which has the bigger context window, Gemini 3.1 Flash Lite Preview or Mercury 2.5?
Gemini 3.1 Flash Lite Preview, with 1.05M tokens against 260K.
How many benchmarks is the Gemini 3.1 Flash Lite Preview vs Mercury 2.5 comparison based on?
12 benchmarks have a result for both models as of October 22, 2026. Gemini 3.1 Flash Lite Preview's coding index rests on 3 independent benchmarks and Mercury 2.5's on 2. Where only one model has a result, the page says so instead of naming a winner.