Mistral Small 4 API

About Mistral Small 4

Hybrid model unifying Instruct, Reasoning (Magistral), and Devstral families: 40% lower completion time and 3x throughput vs Small 3.

Also known as Mistral AI Mistral Small 4, Mistral-Small-4

Mistral Small 4 specs

Model ID

mistral-small-4

Provider

Mistral AI

Category

Text Generation

Released

Mar 16, 2026

Context window

256K tokens

Max output

65,536 tokens

Input

TextImage

Output

Text

Structured output

JSON Mode

Batch API

Available, 35% off list price

Endpoints

POST/v1/chat/completionsPOST/v1/responsesPOST/v1/messagesPOST/v1beta/models/mistral-small-4:generateContent

Alternate model IDs

mistralai/mistral-small-4

Mistral Small 4 API pricing

Live pay-as-you-go rates from the EmpirioLabs catalog. You are billed only for what you use, with no monthly minimum.

How to call the Mistral Small 4 API

Mistral Small 4 serves the OpenAI-compatible Chat Completions API. Point any OpenAI SDK at https://api.empiriolabs.ai/v1 with your EmpirioLabs API key and use the model id mistral-small-4. Get an API key from the EmpirioLabs dashboard.

curl https://api.empiriolabs.ai/v1/chat/completions \
  -H "Authorization: Bearer $EMPIRIOLABS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "mistral-small-4",
    "messages": [
      {"role": "user", "content": "Write a haiku about the ocean."}
    ]
  }'

from openai import OpenAI

client = OpenAI(
    base_url="https://api.empiriolabs.ai/v1",
    api_key="YOUR_EMPIRIOLABS_API_KEY",
)

response = client.chat.completions.create(
    model="mistral-small-4",
    messages=[{"role": "user", "content": "Write a haiku about the ocean."}],
)
print(response.choices[0].message.content)

Mistral Small 4 API parameters

Request parameters supported by the Mistral Small 4 API on EmpirioLabs. Defaults apply when a field is omitted.

Good to know

Tools (web search, code interpreter, image generation) are billed only when actually invoked. Requests that include your own function tools use standard function calling, and the built-in tools are unavailable on those requests: a request cannot combine both at once.

Per-tool billing (usage.tool_usage)

When this model invokes built-in tools (web search, code interpreter, etc.) inside a single request, the response carries a normalized usage.tool_usage map alongside the token counts. The example below shows the shape — exact field names, units, and which tools appear can vary slightly per provider:

"usage": {
  "prompt_tokens": 123,
  "completion_tokens": 456,
  "cost_usd": 0.0042,
  "tool_usage": {"web_search": 3, "code_interpreter": 1}
}

The tool counts are already factored into cost_usd — they are surfaced for transparency so you can audit per-tool billing. The field is omitted when no tools were invoked.

Mistral Small 4 API: common questions

How much does the Mistral Small 4 API cost?

On EmpirioLabs, Mistral Small 4 is billed pay as you go: Input $0.15 per 1M prompt tokens; Output $0.60 per 1M generated tokens; Standard Web Search $0.084 per call. The live rate card on this page always matches what the API charges.

What is the context window of Mistral Small 4?

Mistral Small 4 supports a 256K-token context window with up to 65,536 output tokens per response.

Is the Mistral Small 4 API OpenAI-compatible?

Yes. Mistral Small 4 serves the OpenAI-compatible Chat Completions API, so existing OpenAI SDKs work by pointing base_url at https://api.empiriolabs.ai/v1 and setting the model id to mistral-small-4.

Can I try Mistral Small 4 in the browser before integrating?

Yes. The EmpirioLabs playground runs Mistral Small 4 in the browser with the same parameters the API exposes, so you can test prompts before writing code.

How do I get a Mistral Small 4 API key?

Create an EmpirioLabs account, then generate a key under API Keys in the dashboard. Billing is pay-as-you-go credits, so you only pay for the requests you make.