How much does Step 3.5 Flash 2603 cost per month?

For a chatbot handling 10,000 requests a day with 1,000 input and 500 output tokens each, Step 3.5 Flash 2603 costs about $75.00 per month at StepFun's list prices ($0.10 per 1M input tokens, $0.30 per 1M output tokens).

Does Step 3.5 Flash 2603 support prompt caching?

Yes. Cached input costs $0.02 per 1M tokens, compared with $0.10 for regular input.

How long is Step 3.5 Flash 2603's context window?

Step 3.5 Flash 2603 accepts up to 256,000 tokens (256K) of context and returns up to 256,000 tokens per response.

Step 3.5 Flash 2603 API Pricing

StepFun · released Apr 2, 2026 · 256K context · API model ID step-3.5-flash-2603

Step 3.5 Flash 2603 by StepFun API pricing: $0.10 per 1M input tokens and $0.30 per 1M output tokens (provider list price via models.dev, Oct 10, 2026).

Prices

Step 3.5 Flash 2603 prices, USD per 1M tokens
Price	USD per 1M tokens
Input	$0.10
Output	$0.30
Cache read	$0.02
Cache write	Not published

StepFun's list price for its own API, as compiled by models.dev and checked Oct 10, 2026, 09:00 UTC. Prices on cloud platforms and resellers can differ. Provider documentation

Estimated monthly cost

$75.00

per month

per day: $2.50
per request: $0.00025

Cost = input tokens × input price + output tokens × output price, 30 days a month. Cached input uses the cache read price. Cache write fees are not included.

Compare this workload across models

Monthly cost by workload

Workload	Per month
Chatbot1,000 in / 500 out tokens, 10,000 requests a day	$75.00/mo
RAG8,000 in / 500 out tokens, 5,000 requests a day	$142.50/mo
Coding agent50,000 in / 2,000 out tokens, 1,000 requests a day, 80% cached input	$72.00/mo

Context and capabilities

Context: 256,000 tokens
Max output: 256,000 tokens
Input: text
Output: text
Knowledge cutoff: January 2025
Open weights: Yes
Tool calling: Yes
Reasoning: Yes
Structured outputs: No

Capabilities and limits as listed by models.dev.

Similarly priced models

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Qwen3.8 Flash · $0.15 in / $0.47 out
DeepSeek V4.1 Flash · $0.30 in / $1.20 out

Price history

No price changes since we started tracking on Oct 8, 2026.

Questions

How much does Step 3.5 Flash 2603 cost per month?: For a chatbot handling 10,000 requests a day with 1,000 input and 500 output tokens each, Step 3.5 Flash 2603 costs about $75.00 per month at StepFun's list prices ($0.10 per 1M input tokens, $0.30 per 1M output tokens).
Does Step 3.5 Flash 2603 support prompt caching?: Yes. Cached input costs $0.02 per 1M tokens, compared with $0.10 for regular input.
How long is Step 3.5 Flash 2603's context window?: Step 3.5 Flash 2603 accepts up to 256,000 tokens (256K) of context and returns up to 256,000 tokens per response.