Model comparison
Gemini 3.1 Pro Preview vs Mercury 2.5
Gemini 3.1 Pro Preview is the stronger model overall, scoring 56.7 to 33.5 on the Noometry Index. Mercury 2.5 costs 67× less per token, which makes it the better buy when Gemini 3.1 Pro Preview's lead doesn't matter for your workload.
Last verified . 4 shared benchmarks.
GoogleSummary
- They share 4 benchmarks with published results for both. Gemini 3.1 Pro Preview scores higher in 3 categories and Mercury 2.5 in 0 categories; 3 gaps are clear of the uncertainty.
- The widest gap is in reasoning, where Gemini 3.1 Pro Preview leads 71.7 to 22.4.
- The biggest single-benchmark swing is ProofBench: 26% for Gemini 3.1 Pro Preview and 3% for Mercury 2.5.
- Mercury 2.5 is cheaper at $0.04 / $0.15 per million input/output tokens, against $2 / $12 for Gemini 3.1 Pro Preview.
- Gemini 3.1 Pro Preview accepts more context: 1.05M tokens versus 260K.
Side by side
| Gemini 3.1 Pro Preview | Mercury 2.5 | |
|---|---|---|
| Provider | Inception | |
| Noometry Index | 56.7 | 33.5 |
| Released | 2026-02-19 | 2026-09-08 |
| Weights | Proprietary | Proprietary |
| Context window | 1.05M | 260K |
| Max output | 66K | 66K |
| Input $ / M tokens | $2 | $0.04 |
| Output $ / M tokens | $12 | $0.15 |
| Results tracked | 71 | 4 |
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Category by category
Coding Gemini 3.1 Pro Preview leads
Gemini 3.1 Pro Preview: 42.5 (#99), Mercury 2.5: 39.5 (#156)
| Benchmark | Gemini 3.1 Pro Preview | Mercury 2.5 |
|---|---|---|
| SciCode | 58.9% | 38.5% |
| ALE-Bench | 1,161 | 301.65 |
| SWE-bench Verified | 75.6% | — |
| DeepSWE | 11.7% | — |
| LMArena WebDev | 1447 | — |
| GSO | 22.6% | — |
| WeirdML | 72.1% | — |
| LMArena Coding | 1484 | — |
| MirrorCode | 8.9% | — |
| AlgoTune | 2.02 | — |
Agentic & Tool Use Not comparable
Gemini 3.1 Pro Preview: 37.7 (#34), Mercury 2.5: —
| Benchmark | Gemini 3.1 Pro Preview | Mercury 2.5 |
|---|---|---|
| Terminal-Bench | 80.2% | — |
| APEX-Agents | 35.3% | — |
| τ²-bench Banking | 26% | — |
| DeepResearch Bench | 47.8% | — |
| PostTrainBench | 22% | — |
| BALROG | 57% | — |
| ExploitBench | 26.1% | — |
| GBAEval | 0.8% | — |
| GDP.pdf | 17% | — |
| LMArena Search | 1211 | — |
| METR Time Horizons | 77% | — |
| Vending-Bench 2 | 3,774 | — |
Reasoning Gemini 3.1 Pro Preview leads
Gemini 3.1 Pro Preview: 71.7 (#12), Mercury 2.5: 22.4 (#193)
| Benchmark | Gemini 3.1 Pro Preview | Mercury 2.5 |
|---|---|---|
| CritPt | 17.7% | 0% |
| ARC-AGI-2 | 77.1% | — |
| SimpleBench | 79.6% | — |
| NYT Connections (extended) | 97.4% | — |
| ARC-AGI-1 | 98% | — |
| Chess Puzzles | 55% | — |
| EnigmaEval | 36.8% | — |
| Thematic Generalization | 79.4% | — |
| EBR-Bench | 14.3% | — |
| LMArena Hard Prompts | 1485 | — |
| Mystery Game Puzzles | 34% | — |
| DTBench | 97.1% | — |
| LMCA | 53.8% | — |
| Epoch Capabilities Index | 154.77 | — |
| ForecastBench | 59 | — |
Math Gemini 3.1 Pro Preview leads
Gemini 3.1 Pro Preview: 62.1 (#34), Mercury 2.5: 23.3 (#272)
| Benchmark | Gemini 3.1 Pro Preview | Mercury 2.5 |
|---|---|---|
| ProofBench | 26% | 3% |
| FrontierMath (Tiers 1-3) | 59.6% | — |
| FrontierMath Tier 4 | 26.8% | — |
| MathArena Final-Answer Competitions | 86.5% | — |
| OTIS Mock AIME 2024-2025 | 95.6% | — |
| LMArena Math | 1485 | — |
| FrontierMath (Feb 2025 set) | 36.9% | — |
| FrontierMath Tier 4 (v1) | 16.7% | — |
Knowledge Not comparable
Gemini 3.1 Pro Preview: 71.8 (#3), Mercury 2.5: —
| Benchmark | Gemini 3.1 Pro Preview | Mercury 2.5 |
|---|---|---|
| GPQA Diamond | 94.4% | — |
| Humanity's Last Exam | 46.4% | — |
| SimpleQA Verified | 73.5% | — |
| Vectara Hallucination Rate | 10.4% | — |
| LMArena Expert | 1485 | — |
Multimodal Not comparable
Gemini 3.1 Pro Preview: 37.9 (#69), Mercury 2.5: —
| Benchmark | Gemini 3.1 Pro Preview | Mercury 2.5 |
|---|---|---|
| LMArena Vision | 1296 | — |
| Blueprint-Bench 2 | 26.5% | — |
| Furniture Assembly | 26.7% | — |
| LMArena Document | 1444 | — |
Multilingual Not comparable
Gemini 3.1 Pro Preview: 57.0 (#12), Mercury 2.5: —
| Benchmark | Gemini 3.1 Pro Preview | Mercury 2.5 |
|---|---|---|
| LMArena Non-English | 1477 | — |
| LMArena Chinese | 1529 | — |
| LMArena French | 1487 | — |
| LMArena German | 1491 | — |
| LMArena Japanese | 1493 | — |
| LMArena Korean | 1455 | — |
| LMArena Russian | 1498 | — |
| LMArena Spanish | 1479 | — |
Instruction Following Not comparable
Gemini 3.1 Pro Preview: 77.0 (#32), Mercury 2.5: —
| Benchmark | Gemini 3.1 Pro Preview | Mercury 2.5 |
|---|---|---|
| LMArena Instruction Following | 1466 | — |
Long Context Not comparable
Gemini 3.1 Pro Preview: 47.4 (#18), Mercury 2.5: —
| Benchmark | Gemini 3.1 Pro Preview | Mercury 2.5 |
|---|---|---|
| CL-bench | 20.8% | — |
| CL-bench Life | 16.9% | — |
| LMArena Longer Query | 1483 | — |
Writing & Preference Not comparable
Gemini 3.1 Pro Preview: 66.1 (#37), Mercury 2.5: —
| Benchmark | Gemini 3.1 Pro Preview | Mercury 2.5 |
|---|---|---|
| LMArena Text | 1481 | — |
| LMArena Creative Writing | 1482 | — |
| EQ-Bench Creative Writing | 1491 | — |
| EQ-Bench 4 | 1142 | — |
| LMArena Multi-Turn | 1488 | — |
Frequently asked questions
Is Gemini 3.1 Pro Preview better than Mercury 2.5?
Gemini 3.1 Pro Preview is the stronger model overall, scoring 56.7 to 33.5 on the Noometry Index. Mercury 2.5 costs 67× less per token, which makes it the better buy when Gemini 3.1 Pro Preview's lead doesn't matter for your workload.
Which is cheaper, Gemini 3.1 Pro Preview or Mercury 2.5?
Mercury 2.5 is cheaper. It lists at $0.04 per million input tokens and $0.15 per million output tokens; Gemini 3.1 Pro Preview lists at $2 and $12.
Is Gemini 3.1 Pro Preview or Mercury 2.5 better for coding?
Gemini 3.1 Pro Preview scores higher on coding benchmarks: 42.5 versus 39.5 in the Noometry coding category.
Which has the bigger context window?
Gemini 3.1 Pro Preview does, with 1.05M tokens against 260K.
How many benchmarks do Gemini 3.1 Pro Preview and Mercury 2.5 share?
4 benchmarks have published results for both models. Gemini 3.1 Pro Preview has 71 scored results on Noometry and Mercury 2.5 has 4.