Gemini 3 Flash Preview vs Mercury 2.5
Gemini 3 Flash Preview leads Mercury 2.5 on coding, 43.7 to 1.6 on the Vibe Coding Index, and Mercury 2.5 costs 20.0x less per output token ($0.15 vs $3.00 per million). Updated October 21, 2026; 15 benchmarks have a result for both.
Gemini 3 Flash Preview or Mercury 2.5: which to pick
Pick Gemini 3 Flash Preview for coding: it scores 43.7 on the Vibe Coding Index against 1.6 for Mercury 2.5.
Pick Mercury 2.5 for output tokens 20.0x cheaper ($0.15 vs $3.00 per million).
- Shared results
- 15
- Gemini 3 Flash Preview only
- 56
- Mercury 2.5 only
- 7
- 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
Gemini 3 Flash Preview
Gemini 3 Flash Preview scores 43.7 against 1.6.
2 benchmarks behind each score
Intelligence
AA Intelligence Index
Gemini 3 Flash Preview
Gemini 3 Flash Preview leads, 26.3 against 12.3.
Same board, both measured
Reasoning
GPQA Diamond
No call
Only Gemini 3 Flash Preview has a GPQA Diamond result, 87.9%.
Directional only
Math
AIME
No call
Only Gemini 3 Flash Preview has a AIME result, 95.6%.
Directional only
Knowledge
MMLU Pro
No call
Only Gemini 3 Flash Preview has a MMLU Pro result, 88.6%.
Directional only
Web design
Design Arena: websites
No call
Only Gemini 3 Flash Preview has a Design Arena: websites result, 1196.
Directional only
Long documents
Listed context window
Gemini 3 Flash Preview
Gemini 3 Flash Preview takes 1.05M tokens against 260K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Mercury 2.5
Gemini 3 Flash Preview $0.0020, Mercury 2.5 $0.0001 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Gemini 3 Flash Preview has the number, $0.37.
Directional only
At a glance
- Coding index
- Gemini 3 Flash Preview 43.7 from 2 benchmarks, Mercury 2.5 1.6 from 2 benchmarks.
- Widest category
- Reasoning, 24.8 points apart on average over 1 shared benchmark.
- Widest single gap
- ALE-Bench: Gemini 3 Flash Preview 1367.2 against Mercury 2.5 301.6, 35.5 points apart on a 0 to 100 scale.
- Output price
- Gemini 3 Flash Preview $3.00 against Mercury 2.5 $0.15 per million output tokens, 20.0x apart.
- Context window
- Gemini 3 Flash 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 Flash Preview | Bars | Mercury 2.5 | Ties |
|---|---|---|---|---|
| Coding | 4 | 0 | ||
| Intelligence | 1 | 0 | ||
| Agentic work | 4 | 0 | ||
| Reasoning | 1 | 0 | ||
| Math | 1 | 0 | ||
| Knowledge | 2 | 0 | ||
| General | 2 | 0 | ||
| All shared boards | 15 | 0 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index40
| Benchmark | Gemini 3 Flash Preview | Mercury 2.5 | Leader |
|---|---|---|---|
| SWE-bench Verified | 75.8% | Not measured | Only Gemini 3 Flash Preview measured |
| LiveCodeBench (Vals AI) | 85.6% | Not measured | Only Gemini 3 Flash Preview measured |
| SWE-bench Verified (Vals AI) | 75.0% | Not measured | Only Gemini 3 Flash Preview measured |
| Terminal-Bench 4 (Vals AI) | Not measured | 0.0% | Only Mercury 2.5 measured |
| Vibe Code Bench (Vals AI) | 20.2% | 3.7% | Gemini 3 Flash Preview |
| Code migration (Vals AI) | 6.4% | 4.5% | Gemini 3 Flash Preview |
| ProgramBench (Vals AI) | 0.0% | Not measured | Only Gemini 3 Flash Preview measured |
| IOI (Vals AI) | Not measured | 2.4% | Only Mercury 2.5 measured |
| Terminal-Bench 2.1 (Vals AI) | 53.9% | 34.5% | Gemini 3 Flash Preview |
| SkillsBench (Vals AI) | Not measured | 18.1% | Only Mercury 2.5 measured |
| CyberBench (Vals AI) | Not measured | 45.5% | Only Mercury 2.5 measured |
| LiveCodeBench (Artificial Analysis run) | 90.8% | Not measured | Only Gemini 3 Flash Preview measured |
| SciCode | Not measured | 38.5% | Only Mercury 2.5 measured |
| Terminal-Bench Hard (Artificial Analysis run) | 38.6% | Not measured | Only Gemini 3 Flash Preview measured |
| Terminal-Bench | 64.3% | Not measured | Only Gemini 3 Flash Preview measured |
| GSO-Bench | 9.8% | Not measured | Only Gemini 3 Flash Preview measured |
| WeirdML | 61.6% | Not measured | Only Gemini 3 Flash Preview measured |
| ALE-Bench | 1367.2 | 301.6 | Gemini 3 Flash Preview |
| SciCode | 12.7% | Not measured | Only Gemini 3 Flash Preview measured |
| Neither model has a result on the other 20 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Gemini 3 Flash Preview | Mercury 2.5 | Leader |
|---|---|---|---|
| AA Intelligence Index | 26.3 | 12.3 | Gemini 3 Flash Preview |
| Neither model has a result on the other 1 board here | |||
Agentic workLike-for-likePublic boards, shown as published, kept out of the index40
| Benchmark | Gemini 3 Flash Preview | Mercury 2.5 | Leader |
|---|---|---|---|
| Design Arena: agents building web apps | 1110 | Not measured | Only Gemini 3 Flash Preview measured |
| Design Arena: agents building full-stack apps | 1063 | Not measured | Only Gemini 3 Flash Preview measured |
| Design Arena: agents building mobile apps | 1090 | Not measured | Only Gemini 3 Flash Preview measured |
| Design Arena: agents building Android apps | 1050 | Not measured | Only Gemini 3 Flash Preview measured |
| Design Arena: agents building Godot games | 1161 | Not measured | Only Gemini 3 Flash Preview measured |
| Design Arena: PowerPoint slides | 1036 | Not measured | Only Gemini 3 Flash Preview measured |
| Finance Agent (Vals AI) | 42.5% | 18.9% | Gemini 3 Flash Preview |
| Tax Agent Bench (Vals AI) | 11.8% | 2.5% | Gemini 3 Flash Preview |
| Legal Research Bench (Vals AI) | 18.3% | 4.3% | Gemini 3 Flash Preview |
| Excel Modeling Benchmark (Vals AI) | 26.0% | 8.8% | Gemini 3 Flash Preview |
| Terminal-Bench-Science (Vals AI) | Not measured | 0.0% | Only Mercury 2.5 measured |
| τ²-Bench Telecom | 80.4% | Not measured | Only Gemini 3 Flash Preview measured |
| BALROG | 48.1% | Not measured | Only Gemini 3 Flash Preview measured |
| DeepResearch Bench | 49.8% | Not measured | Only Gemini 3 Flash Preview measured |
| Vending-Bench 2 | $3,635 | Not measured | Only Gemini 3 Flash Preview measured |
| Neither model has a result on the other 26 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Gemini 3 Flash Preview | Mercury 2.5 | Leader |
|---|---|---|---|
| GPQA Diamond | 87.9% | Not measured | Only Gemini 3 Flash Preview measured |
| MMMU Pro (Vals AI) | 87.6% | Not measured | Only Gemini 3 Flash Preview measured |
| GPQA Diamond (Artificial Analysis run) | 89.8% | Not measured | Only Gemini 3 Flash Preview measured |
| Humanity's Last Exam (Artificial Analysis run) | 36.6% | 11.8% | Gemini 3 Flash Preview |
| GPQA Diamond (Epoch AI run) | 89.4% | Not measured | Only Gemini 3 Flash Preview measured |
| ARC-AGI | 84.7% | Not measured | Only Gemini 3 Flash Preview measured |
| ARC-AGI-2 | 33.6% | Not measured | Only Gemini 3 Flash Preview measured |
| SimpleBench | 61.1% | Not measured | Only Gemini 3 Flash Preview measured |
| Chess puzzles | 39.0% | Not measured | Only Gemini 3 Flash Preview measured |
| Mystery game puzzles | 26.0% | Not measured | Only Gemini 3 Flash Preview measured |
| VPCT | 72.6% | Not measured | Only Gemini 3 Flash Preview measured |
| Neither model has a result on the other 11 boards here | |||
MathLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Gemini 3 Flash Preview | Mercury 2.5 | Leader |
|---|---|---|---|
| AIME | 95.6% | Not measured | Only Gemini 3 Flash Preview measured |
| MGSM (Vals AI) | 93.3% | Not measured | Only Gemini 3 Flash Preview measured |
| AA Math Index | 97.0 | Not measured | Only Gemini 3 Flash Preview measured |
| AIME 2025 (Artificial Analysis run) | 97.0% | Not measured | Only Gemini 3 Flash Preview measured |
| OTIS Mock AIME | 95.6% | Not measured | Only Gemini 3 Flash Preview measured |
| FrontierMath, tiers 1 to 3 | 51.2% | Not measured | Only Gemini 3 Flash Preview measured |
| FrontierMath, tier 4 | 17.1% | Not measured | Only Gemini 3 Flash Preview measured |
| ProofBench | 15.0% | 3.0% | Gemini 3 Flash Preview |
| Neither model has a result on the other 5 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Gemini 3 Flash Preview | Mercury 2.5 | Leader |
|---|---|---|---|
| MMLU Pro | 88.6% | Not measured | Only Gemini 3 Flash Preview measured |
| LegalBench (Vals AI) | 86.9% | 83.1% | Gemini 3 Flash Preview |
| CaseLaw (Vals AI) | 55.8% | Not measured | Only Gemini 3 Flash Preview measured |
| CorpFin (Vals AI) | 66.4% | Not measured | Only Gemini 3 Flash Preview measured |
| TaxEval (Vals AI) | 73.9% | Not measured | Only Gemini 3 Flash Preview measured |
| MortgageTax (Vals AI) | 68.7% | Not measured | Only Gemini 3 Flash Preview measured |
| MedQA (Vals AI) | 95.8% | Not measured | Only Gemini 3 Flash Preview measured |
| MedCode (Vals AI) | 55.9% | 31.3% | Gemini 3 Flash Preview |
| MMLU Pro (Artificial Analysis run) | 89.0% | Not measured | Only Gemini 3 Flash Preview measured |
| SimpleQA Verified | 66.8% | Not measured | Only Gemini 3 Flash Preview measured |
| GeoBench | 88.0% | Not measured | Only Gemini 3 Flash Preview measured |
| FACTS Benchmark Suite | 63.4% | Not measured | Only Gemini 3 Flash Preview measured |
| Neither model has a result on the other 6 boards here | |||
Web designDirectional onlyPublic boards, shown as published, kept out of the index4 boards, none shared
| Benchmark | Gemini 3 Flash Preview | Mercury 2.5 | Leader |
|---|---|---|---|
| Design Arena: websites | 1196 | Not measured | Only Gemini 3 Flash Preview measured |
| Design Arena: game dev | 1166 | Not measured | Only Gemini 3 Flash Preview measured |
| Design Arena: 3D | 1184 | Not measured | Only Gemini 3 Flash Preview measured |
| Design Arena: all code categories | 1189 | Not measured | Only Gemini 3 Flash Preview measured |
| Neither model has a result on the other 5 boards here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Gemini 3 Flash Preview | Mercury 2.5 | Leader |
|---|---|---|---|
| Public Benefits Bench (Vals AI) | Not measured | 45.3% | Only Mercury 2.5 measured |
| SAGE (Vals AI) | 51.8% | Not measured | Only Gemini 3 Flash Preview measured |
| MedScribe (Vals AI) | 69.9% | 55.1% | Gemini 3 Flash Preview |
| Vals Multimodal Index | 52.2% | Not measured | Only Gemini 3 Flash Preview measured |
| IFBench | 78.0% | Not measured | Only Gemini 3 Flash Preview measured |
| Long context reasoning (AA-LCR) | 78.0% | 71.7% | Gemini 3 Flash Preview |
| DTBench | 89.1% | Not measured | Only Gemini 3 Flash Preview measured |
| LMCA | 43.1% | Not measured | Only Gemini 3 Flash Preview measured |
| Neither model has a result on the other 38 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Gemini 3 Flash 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 Flash Preview | Inception Mercury 2.5 |
|---|---|---|
| Maker | Inception | |
| Weights | No public weights listed | No public weights listed |
| Released | December 17, 2025 | September 8, 2026 |
| Context window | 1.05M | 260K |
| Input $/Mtok | $0.50 | $0.04 |
| Output $/Mtok | $3.00 | $0.15 |
| Coding index | 43.7 | 1.6 |
| Independent measurements behind it | 2 | 2 |
| Cost per solved task | $0.37 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Gemini 3 Flash Preview better than Mercury 2.5 for coding?
Pick Gemini 3 Flash Preview for coding: it scores 43.7 on the Vibe Coding Index against 1.6 for Mercury 2.5. Pick Mercury 2.5 for output tokens 20.0x cheaper ($0.15 vs $3.00 per million).
Which is cheaper, Gemini 3 Flash Preview or Mercury 2.5?
Gemini 3 Flash Preview costs $0.50 per million input tokens and $3.00 per million output tokens; Mercury 2.5 costs $0.04 and $0.15. Cost per solved task is known for Gemini 3 Flash Preview only.
Which has the bigger context window, Gemini 3 Flash Preview or Mercury 2.5?
Gemini 3 Flash Preview, with 1.05M tokens against 260K.
How many benchmarks is the Gemini 3 Flash Preview vs Mercury 2.5 comparison based on?
15 benchmarks have a result for both models as of October 21, 2026. Gemini 3 Flash Preview's coding index rests on 2 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.