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About
Step 3.5 Flash is StepFun's most capable open-source foundation model. Built on a sparse Mixture of Experts (MoE) architecture, it selectively activates only 11B of its 196B parameters per token....
Pricing
Input
$0.10
per 1M tokens
Output
$0.30
per 1M tokens
Blended
$0.15
per 1M tokens
Cheaper than 75% of models. Median price is $0.56/1M tokens.
Cost Calculator
Tokens per day1M
100K100M
Daily
$0.15
Monthly
$4.50
vs. Similar Models
Grok 4.1 Fast (Reasoning)Q:+0.1
$0.28+83%
OpenAI: GPT-5.1-Codex-MiniQ:+0.1
$0.69+358%
Qwen3.5 Omni PlusQ:+0.1
$1.50+900%
OpenAI: o3Q:-0.1
$3.50+2233%
Performance
174
tokens/sec
Faster than 86% of models
0.87
seconds
Faster than 61% of models
12.40
seconds
Faster than 36% of models
Market Median
86 tok/s
102% faster
Median TTFT
1.07s
18% faster
Throughput/Dollar
1157
tok/s per $/1M
Speed Comparison
Step 3.5 Flash
174 tok/s+0%
OpenAI: GPT-5.4 Mini
174 tok/s+1%
Nova 2.0 Lite (high)
172 tok/s-1%
Context Window
262K
tokens
Larger than 66% of models
Max Output
66K
tokens
25% of context
Benchmarks
MMLU-ProNot evaluated
GPQA Diamond
82.6%
HLE
22.6%
LiveCodeBenchNot evaluated
SciCode
38.5%
TerminalBench Hard
32.6%
MATH-500Not evaluated
AIMENot evaluated
AIME 2025Not evaluated
IFBench
66.5%
Long Context Recall
54.3%
Tau2
87.4%
Market AverageTop Score
