Model comparison
Mercury vs Step 3.5 Flash
Step 3.5 Flash is the stronger model overall, scoring 42.3 to 37.6 on the Noometry Index.
Last verified . 8 shared benchmarks.
StepFunSummary
- They share 8 benchmarks with published results for both. Mercury scores higher in 0 categories and Step 3.5 Flash in 6 categories; 6 gaps are clear of the uncertainty.
- The widest gap is in writing & preference, where Step 3.5 Flash leads 58.8 to 46.2.
- Step 3.5 Flash has downloadable open weights; the other is API-only.
Side by side
| Mercury | Step 3.5 Flash | |
|---|---|---|
| Provider | Inception | StepFun |
| Noometry Index | 37.6 | 42.3 |
| Released | — | 2026-01-29 |
| Weights | Proprietary | Open |
| Context window | — | 256K |
| Max output | — | 256K |
| Input $ / M tokens | — | $0.10 |
| Output $ / M tokens | — | $0.30 |
| Results tracked | 9 | 19 |
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Category by category
Coding Step 3.5 Flash leads
Mercury: 38.7 (#170), Step 3.5 Flash: 42.4 (#105)
| Benchmark | Mercury | Step 3.5 Flash |
|---|---|---|
| LMArena Coding | 1322 | 1436 |
Reasoning Step 3.5 Flash leads
Mercury: 17.5 (#293), Step 3.5 Flash: 22.2 (#202)
| Benchmark | Mercury | Step 3.5 Flash |
|---|---|---|
| LMArena Hard Prompts | 1285 | 1411 |
| Kagi LLM Benchmark | 21.6% | — |
| NYT Connections (extended) | — | 28.4% |
Math Not comparable
Mercury: —, Step 3.5 Flash: 42.6 (#84)
| Benchmark | Mercury | Step 3.5 Flash |
|---|---|---|
| MathArena Final-Answer Competitions | — | 66.8% |
| LMArena Math | — | 1408 |
Knowledge Not comparable
Mercury: —, Step 3.5 Flash: 39.6 (#132)
| Benchmark | Mercury | Step 3.5 Flash |
|---|---|---|
| LMArena Expert | — | 1421 |
Multilingual Step 3.5 Flash leads
Mercury: 41.6 (#206), Step 3.5 Flash: 50.5 (#119)
| Benchmark | Mercury | Step 3.5 Flash |
|---|---|---|
| LMArena Non-English | 1260 | 1385 |
| LMArena Chinese | — | 1447 |
| LMArena French | — | 1421 |
| LMArena German | — | 1405 |
| LMArena Japanese | — | 1354 |
| LMArena Korean | — | 1352 |
| LMArena Russian | — | 1385 |
| LMArena Spanish | — | 1419 |
Instruction Following Step 3.5 Flash leads
Mercury: 65.2 (#224), Step 3.5 Flash: 73.1 (#124)
| Benchmark | Mercury | Step 3.5 Flash |
|---|---|---|
| LMArena Instruction Following | 1239 | 1385 |
Long Context Step 3.5 Flash leads
Mercury: 38.4 (#198), Step 3.5 Flash: 42.8 (#117)
| Benchmark | Mercury | Step 3.5 Flash |
|---|---|---|
| LMArena Longer Query | 1266 | 1402 |
Writing & Preference Step 3.5 Flash leads
Mercury: 46.2 (#221), Step 3.5 Flash: 58.8 (#113)
| Benchmark | Mercury | Step 3.5 Flash |
|---|---|---|
| LMArena Text | 1282 | 1403 |
| LMArena Creative Writing | 1191 | 1357 |
| LMArena Multi-Turn | 1282 | 1405 |
Frequently asked questions
Is Mercury better than Step 3.5 Flash?
Step 3.5 Flash is the stronger model overall, scoring 42.3 to 37.6 on the Noometry Index.
Is Mercury or Step 3.5 Flash better for coding?
Step 3.5 Flash scores higher on coding benchmarks: 42.4 versus 38.7 in the Noometry coding category.
How many benchmarks do Mercury and Step 3.5 Flash share?
8 benchmarks have published results for both models. Mercury has 9 scored results on Noometry and Step 3.5 Flash has 19.