Step 3.5 Flash

Step 3.5 Flash is a StepFun open-weights reasoning model, released 29 Jan 2026. Its best configuration ranks #248 of 756 on the BenchLeader Index at 54.0 ±3.6, in the upper half. The ± is the point: 272 other configurations score within that range, so they and this one cannot be told apart on quality alone — price and speed are what separate them. It scores highest in instruction following (66) and lowest in knowledge (43). At $0.150 per million tokens blended it is among the cheapest fifth of ranked models. Output speed of 133 tokens per second puts it in the fastest quarter, with a first answer in 18.5 s. Last measured 2 Oct 2026.

Blended price

$0.150/M

$0.100 in · $0.300 out

Output speed

133 tok/s

measured by Artificial Analysis

First answer

18 s

first token 1.27 s

Context

256k

Full answer

22 s

median, reasoning included

Cost per run

–

Released

29 Jan 2026