Model comparison
Mercury 2 vs Mercury 2.5
Mercury 2 is the stronger model overall, scoring 39.1 to 33.5 on the Noometry Index. Mercury 2.5 costs 5.6× less per token, which makes it the better buy when Mercury 2's lead doesn't matter for your workload.
Last verified . 3 shared benchmarks.
Summary
- They share 3 benchmarks with published results for both. Mercury 2 scores higher in 1 category and Mercury 2.5 in 1 category; 2 gaps are clear of the uncertainty.
- The widest gap is in coding, where Mercury 2.5 leads 39.5 to 33.5.
- Mercury 2.5 is cheaper at $0.04 / $0.15 per million input/output tokens, against $0.25 / $0.75 for Mercury 2.
- Mercury 2.5 accepts more context: 260K tokens versus 128K.
Side by side
| Mercury 2 | Mercury 2.5 | |
|---|---|---|
| Provider | Inception | Inception |
| Noometry Index | 39.1 | 33.5 |
| Released | 2026-02-20 | 2026-09-08 |
| Weights | Proprietary | Proprietary |
| Context window | 128K | 260K |
| Max output | 50K | 66K |
| Input $ / M tokens | $0.25 | $0.04 |
| Output $ / M tokens | $0.75 | $0.15 |
| Results tracked | 17 | 4 |
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Category by category
Coding Mercury 2.5 leads
Mercury 2: 33.5 (#255), Mercury 2.5: 39.5 (#156)
| Benchmark | Mercury 2 | Mercury 2.5 |
|---|---|---|
| SciCode | 38.7% | 38.5% |
| ALE-Bench | 785.58 | 301.65 |
| LMArena WebDev | 1171 | — |
| WeirdML | 43.2% | — |
| LMArena Coding | 1391 | — |
Reasoning Mercury 2 leads
Mercury 2: 23.8 (#170), Mercury 2.5: 22.4 (#193)
| Benchmark | Mercury 2 | Mercury 2.5 |
|---|---|---|
| CritPt | 0.8% | 0% |
| LMArena Hard Prompts | 1362 | — |
Math Not comparable
Mercury 2: —, Mercury 2.5: 23.3 (#272)
| Benchmark | Mercury 2 | Mercury 2.5 |
|---|---|---|
| ProofBench | — | 3% |
Knowledge Not comparable
Mercury 2: 36.2 (#172), Mercury 2.5: —
| Benchmark | Mercury 2 | Mercury 2.5 |
|---|---|---|
| Vectara Hallucination Rate | 12.3% | — |
| LMArena Expert | 1358 | — |
Multilingual Not comparable
Mercury 2: 46.6 (#157), Mercury 2.5: —
| Benchmark | Mercury 2 | Mercury 2.5 |
|---|---|---|
| LMArena Non-English | 1331 | — |
| LMArena Chinese | 1417 | — |
| LMArena Russian | 1304 | — |
Instruction Following Not comparable
Mercury 2: 70.2 (#165), Mercury 2.5: —
| Benchmark | Mercury 2 | Mercury 2.5 |
|---|---|---|
| LMArena Instruction Following | 1329 | — |
Long Context Not comparable
Mercury 2: 40.5 (#154), Mercury 2.5: —
| Benchmark | Mercury 2 | Mercury 2.5 |
|---|---|---|
| LMArena Longer Query | 1330 | — |
Writing & Preference Not comparable
Mercury 2: 53.8 (#155), Mercury 2.5: —
| Benchmark | Mercury 2 | Mercury 2.5 |
|---|---|---|
| LMArena Text | 1355 | — |
| LMArena Creative Writing | 1289 | — |
| LMArena Multi-Turn | 1358 | — |
Frequently asked questions
Is Mercury 2 better than Mercury 2.5?
Mercury 2 is the stronger model overall, scoring 39.1 to 33.5 on the Noometry Index. Mercury 2.5 costs 5.6× less per token, which makes it the better buy when Mercury 2's lead doesn't matter for your workload.
Which is cheaper, Mercury 2 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; Mercury 2 lists at $0.25 and $0.75.
Is Mercury 2 or Mercury 2.5 better for coding?
Mercury 2.5 scores higher on coding benchmarks: 39.5 versus 33.5 in the Noometry coding category.
Which has the bigger context window?
Mercury 2.5 does, with 260K tokens against 128K.
How many benchmarks do Mercury 2 and Mercury 2.5 share?
3 benchmarks have published results for both models. Mercury 2 has 17 scored results on Noometry and Mercury 2.5 has 4.