How much does Step 3.5 Flash cost per million tokens?

Step 3.5 Flash costs $0.1 per million input tokens and $0.3 per million output tokens at list price.

What is the context window of Step 3.5 Flash?

Step 3.5 Flash accepts up to 262,144 tokens of context and returns up to 65,536 output tokens.

How much do 1,000 chat messages cost with Step 3.5 Flash?

About $0.25, assuming 1,000 input + 500 output tokens per message.

Is there a cheaper alternative to Step 3.5 Flash?

In the same price range, DeepSeek DeepSeek V4.1 Flash ($0.03 / $0.5), Qwen Qwen3.7 Flash ($0.03 / $0.13), DeepSeek DeepSeek V4 Flash 0423 ($0.042 / $0.084) cost less per token. Quality differs: test on your own prompts.

Where can I buy StepFun API credits for less?

Discount credit books resell OpenRouter usage below face value within their depth, OpenRouter adds a 5.5% card fee, and StepFun sells its own credits at face value. The live table on this page ranks them for $100 of usage.

StepFun · live price

Step 3.5 Flash API pricing

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....

Small and cheap (under $1 per 1M)Tool callingReasoning

Input: $0.1; per 1M tokens
Output: $0.3; per 1M tokens
Cached input: –; per 1M tokens
Context: 262K; 66K max output

List price from OpenRouter, which passes StepFun's price through without markup. Refreshed hourly. Released January 29, 2026. Model id stepfun/step-3.5-flash.

What Step 3.5 Flash costs in practice

At list price, before any batch or caching discount.

1,000 chat messages

$0.25

1,000 input + 500 output tokens each

1,000 RAG questions

$0.95

8,000 input + 500 output tokens each

100 coding-agent steps

$0.36

30,000 input + 2,000 output tokens each, no caching

Step 3.5 Flash price history

No price change since we started tracking on 2026-10-01. We record prices daily; changes will show here.

Step 3.5 Flash price by host

One host serves this model through OpenRouter.

SiliconFlow$0.1 in · $0.3 out · 262K ctx · 100.0% uptime 24h

Where to buy StepFun credits for less

Step 3.5 Flash costs the same per token everywhere it's sold through OpenRouter. What changes is the price of the credits. Live quotes for $100 of usage:

#	Where you buy	You payYou pay for $100.00 of usage	vs list price	Price source
1	OrbioCardCheapest right now Credits from a discount book, plus a 5% platform fee and card processing, both included in the quote.	$85.10 incl. $2.60 card processing	-14.9%	live quote
2	smaaartCard Credits from a discount book, plus a 5% platform fee on face value. Card processing and taxes shown at checkout.	$95.00 + card processing and tax at checkout (not in this number)	-5.0%	live quote
3	Direct from the labCard Prepaid credits at face value (OpenAI, Anthropic, Google…). Taxes may apply.	$100.00 no top-up fee	list price	face value
4	OpenRouterCrypto 5% on crypto purchases. No markup on model prices.	$105.00 fees included	+5.0%	published fee
5	OpenRouterCard 5.5% on card purchases, $0.80 minimum. No markup on model prices.	$105.50 fees included	+5.5%	published fee

Disclosure: this site is run by the team behind smaaart, one of the options compared. Tables are ranked by price only, from live quotes and published fees, including when smaaart isn't first. How we compare

Step 3.5 Flash cost calculator

Enter your monthly tokens to price your own usage.

Model$0.1 in / $0.3 out per 1M tokens · list price, liveInput tokens / month (millions)Output tokens / month (millions)

Usage at list price$8.00/ month

Cheaper alternatives to Step 3.5 Flash

Other labs' models in the same price range or the one below, cheaper per token.

Model	Input / 1M	Output / 1M	Blended 3:1	Context
DeepSeek: DeepSeek V4.1 Flash	$0.03	$0.5	$0.147	1.0M
Qwen: Qwen3.7 Flash	$0.03	$0.13	$0.055	1M
DeepSeek: DeepSeek V4 Flash 0423	$0.042	$0.084	$0.052	1.0M
Google: Gemma 4 26B A4B	$0.09	$0.3	$0.143	262K
Qwen: Qwen3.5-9B	$0.1	$0.15	$0.112	262K
Qwen: Qwen3.5-Flash	$0.065	$0.26	$0.114	1M

Other StepFun models

Model	Input / 1M	Output / 1M	Blended 3:1	Context
Step 3.7 Flash	$0.2	$1.15	$0.438	262K

All StepFun API prices