Model comparison
Sonar vs Step 3.5 Flash
Step 3.5 Flash is the stronger model overall, scoring 42.3 to 38.5 on the Noometry Index.
Last verified . 0 shared benchmarks.
Perplexity
StepFunSummary
- The widest gap is in math, where Step 3.5 Flash leads 42.6 to 33.7.
- Step 3.5 Flash is cheaper at $0.10 / $0.30 per million input/output tokens, against $1 / $1 for Sonar.
- Step 3.5 Flash accepts more context: 256K tokens versus 128K.
- Step 3.5 Flash has downloadable open weights; the other is API-only.
Side by side
| Sonar | Step 3.5 Flash | |
|---|---|---|
| Provider | Perplexity | StepFun |
| Noometry Index | 38.5 | 42.3 |
| Released | 2024-01-01 | 2026-01-29 |
| Weights | Proprietary | Open |
| Context window | 128K | 256K |
| Max output | 4K | 256K |
| Input $ / M tokens | $1 | $0.10 |
| Output $ / M tokens | $1 | $0.30 |
| Results tracked | 7 | 19 |
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Category by category
Coding Step 3.5 Flash leads
Sonar: 35.7 (#221), Step 3.5 Flash: 42.4 (#105)
| Benchmark | Sonar | Step 3.5 Flash |
|---|---|---|
| LiveBench Coding | 35.1% | — |
| LMArena Coding | — | 1436 |
Reasoning Step 3.5 Flash leads
Sonar: 21.1 (#227), Step 3.5 Flash: 22.2 (#202)
| Benchmark | Sonar | Step 3.5 Flash |
|---|---|---|
| NYT Connections (extended) | — | 28.4% |
| LiveBench Reasoning | 46.3% | — |
| LMArena Hard Prompts | — | 1411 |
| LiveBench Data Analysis | 37.9% | — |
| LiveBench | 46.9% | — |
Math Step 3.5 Flash leads
Sonar: 33.7 (#200), Step 3.5 Flash: 42.6 (#84)
| Benchmark | Sonar | Step 3.5 Flash |
|---|---|---|
| MathArena Final-Answer Competitions | — | 66.8% |
| LiveBench Math | 41.6% | — |
| LMArena Math | — | 1408 |
Knowledge Not comparable
Sonar: —, Step 3.5 Flash: 39.6 (#132)
| Benchmark | Sonar | Step 3.5 Flash |
|---|---|---|
| LMArena Expert | — | 1421 |
Multilingual Not comparable
Sonar: —, Step 3.5 Flash: 50.5 (#119)
| Benchmark | Sonar | Step 3.5 Flash |
|---|---|---|
| LMArena Non-English | — | 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
Sonar: 71.4 (#150), Step 3.5 Flash: 73.1 (#124)
| Benchmark | Sonar | Step 3.5 Flash |
|---|---|---|
| LiveBench Instruction Following | 76.2% | — |
| LMArena Instruction Following | — | 1385 |
Long Context Not comparable
Sonar: —, Step 3.5 Flash: 42.8 (#117)
| Benchmark | Sonar | Step 3.5 Flash |
|---|---|---|
| LMArena Longer Query | — | 1402 |
Writing & Preference Step 3.5 Flash leads
Sonar: 52.6 (#167), Step 3.5 Flash: 58.8 (#113)
| Benchmark | Sonar | Step 3.5 Flash |
|---|---|---|
| LMArena Text | — | 1403 |
| LMArena Creative Writing | — | 1357 |
| LMArena Multi-Turn | — | 1405 |
| LiveBench Language | 44.1% | — |
Frequently asked questions
Is Sonar better than Step 3.5 Flash?
Step 3.5 Flash is the stronger model overall, scoring 42.3 to 38.5 on the Noometry Index.
Which is cheaper, Sonar or Step 3.5 Flash?
Step 3.5 Flash is cheaper. It lists at $0.10 per million input tokens and $0.30 per million output tokens; Sonar lists at $1 and $1.
Is Sonar or Step 3.5 Flash better for coding?
Step 3.5 Flash scores higher on coding benchmarks: 42.4 versus 35.7 in the Noometry coding category.
Which has the bigger context window?
Step 3.5 Flash does, with 256K tokens against 128K.
How many benchmarks do Sonar and Step 3.5 Flash share?
0 benchmarks have published results for both models. Sonar has 7 scored results on Noometry and Step 3.5 Flash has 19.