Qwen3.5-4B
Qwen3.5-4B is a reasoning model from Qwen released on Nov 1, 2025. It reads text, images and video and writes text, with a 262K token context window and up to 66K tokens per reply.
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It costs $0 per million input tokens and $0 per million output tokens.
It supports tool calling, and its weights are open, so you can host it yourself.
2 providers serve it, including QVAC and SiliconFlow (China).
- Modalities
- In / out price
- $0 / $0 per 1M
- Context
- 262K
- Max output
- 66K
- Released
- Nov 1, 2025
- Knowledge cutoff
- Apr 2025
- Tool calling
- Structured output
- Reasoning
- Prompt caching
- Open weights
- Free to use
Qwen3.5-4B pricing
USD, as listed on Oct 15, 2026. Most bills are input heavy, so the cached input rate matters as much as the headline price.
| Input | $0 / 1M tokens | |
|---|---|---|
| Output | $0 / 1M tokens |
Qwen3.5-4B providers
2 providers serve it, including QVAC and SiliconFlow (China). Each host sets its own price and limits, so the cheapest one is not always the one with the longest context.
| Provider | Input /M | Output /M | Cache read /M | Context | Max output |
|---|---|---|---|---|---|
| QVAC | $0 | $0 | – | 33K | 8K |
| SiliconFlow (China) | $0 | $0 | – | 262K | 66K |
What Qwen3.5-4B costs per month
Pick a workload close to yours or type your own volumes.
Supported request parameters
What you can set when you call Qwen3.5-4B through an OpenAI compatible API.
- Tools
tools - Reasoning
reasoning - Temperature
temperature
Alternatives to Qwen3.5-4B
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Qwen3.5-4B questions
How much does the Qwen3.5-4B API cost?
$0 per million input tokens and $0 per million output tokens. The estimator on this page turns that into a monthly bill for your own workload.
What is the context window of Qwen3.5-4B?
262,144 tokens of input, and it can write up to 65,536 tokens in one reply. As a rough guide, a million tokens is around 750,000 English words.
Which providers serve Qwen3.5-4B?
2 providers serve it, including QVAC and SiliconFlow (China). Prices differ by host, so the Providers table on this page lists each one with its input and output price.
Does Qwen3.5-4B support tool calling?
Yes. It accepts tool definitions, which is what an agent needs to call your APIs.
Is Qwen3.5-4B open source?
Its weights are published, so you can run it on your own hardware or a cloud of your choice. Read the license before commercial use.
When was Qwen3.5-4B released?
Nov 1, 2025, with training data up to Apr 2025.
Catalog data from models.dev (MIT licensed), refreshed daily, last on Oct 15, 2026. The summary is written from these facts.
Building on Qwen3.5-4B?
I test your real tasks on it and the two closest alternatives, then ship the agent on whichever wins on cost and accuracy.
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