Step 3.5 Flash API pricing
Official StepFun list price, last checked Oct 29, 2026. Updated Oct 29, 2026.
Step 3.5 Flash costs $0.10 per 1M input tokens and $0.30 per 1M output tokens, cached input at $0.02, per StepFun's official pricing page (checked Oct 29, 2026). It's one of the cheapest models we track: number 2 of 77 by blended price ($0.15 per 1M tokens at a 3 to 1 input to output mix). On LMArena's Text Arena it ranks #51 of 51 models we price (relative score 0 out of 100). Nothing on our list is much cheaper.
Step 3.5 Flash price per million tokens
| Step 3.5 Flash price per million tokens | USD |
|---|---|
| Input | $0.10 |
| Cached input | $0.02 |
| Output | $0.30 |
| Blended, 3 parts input to 1 part output | $0.15 |
| Context window | Not listed |
StepFun lists one flat rate for Step 3.5 Flash: no long-prompt surcharge or tier is shown on the pricing page we checked.
What Step 3.5 Flash costs for real work
List-price estimates for a month, no discounts. Our math, not a quote: change the token counts in the plan vs API calculator.
| Workload | Tokens a month | Step 3.5 Flash | Qwen3.5 Flash |
|---|---|---|---|
| Light: a side project or personal assistant | 2M in, 0.5M out | $0.35 | $0.40 |
| Medium: a small team or one product feature | 20M in, 5M out | $3.50 | $4.00 |
| Heavy: a production app | 200M in, 50M out | $35.00 | $40.00 |
| Medium with 80% of input cached | 20M in (16M cached), 5M out | $2.22 | n/a |
How Step 3.5 Flash ranks on LMArena
Relative score: 100 is the top model we price on that board. Rank is among the models in our price table, not the full leaderboard.
| Board | Rank | Score /100 |
|---|---|---|
| Chat (Text Arena) | #51 of 51 | 0 |
| Creative writing (Text Arena creative writing) | #49 of 51 | 0 |
| Roleplay and characters (Text Arena multi-turn) | #49 of 51 | 0 |
| Reasoning and math (Text Arena math) | #49 of 51 | 0 |
Closest rivals to Step 3.5 Flash
The models nearest in price, other makers first. Ranks are on Text Arena, where we have them.
| Model | In / out | Blended | Verdict |
|---|---|---|---|
| Qwen3.5 Flash | $0.10 / $0.40 | $0.175 | Step 3.5 Flash wins: cheaper, same score. Compare |
| Seed 2.0 Mini | $0.10 / $0.40 | $0.175 | Step 3.5 Flash wins on price. Compare |
| MiMo-V2.6 Flash | $0.14 / $0.28 | $0.175 | Step 3.5 Flash wins: cheaper, same score. Compare |
| ERNIE 4.5 Turbo | $0.11 / $0.45 | $0.195 | Step 3.5 Flash wins on price. Compare |
Cheaper alternatives to Step 3.5 Flash
Nothing in our table is at least 40% cheaper blended. See the cheapest LLM API ranking for the low end.
More from StepFun
FAQ
How much does the Step 3.5 Flash API cost per million tokens?
$0.10 per 1M input tokens and $0.30 per 1M output tokens, plus $0.02 per 1M for cached input, as of Oct 29, 2026. A typical 3 to 1 input to output mix works out to $0.15 per 1M tokens.
Does Step 3.5 Flash charge more for long prompts?
No. StepFun lists a single rate on its pricing page.
Is Step 3.5 Flash cheaper than Qwen3.5 Flash?
Yes. A medium month (20M input and 5M output tokens) costs $3.50 on Step 3.5 Flash and $4.00 on Qwen3.5 Flash at list price. On Text Arena, Step 3.5 Flash ranks #51 and Qwen3.5 Flash #49.
How does Step 3.5 Flash rank on LMArena?
On Text Arena it is #51 of 51 models we price, with a relative score of 0 out of 100. It ranks on 4 of 8 boards we track.
What is a cheaper alternative to Step 3.5 Flash?
Few models undercut it by much. The next closest in price is Qwen3.5 Flash at $0.175 blended.
Where does this Step 3.5 Flash price come from?
From StepFun's official pricing page, which we check every day. This page was last checked Oct 29, 2026.