OpenAI parameter max_tokens minimum


In OpenAI API, is there a minimum value for the max_tokens parameter?

Thank you in anticipation.


Yes, the maximum value is whatever the model size is, 4K, 8k, 16k, 32k, 128K minus your prompt size in tokens.


The question is about a “minimum” max_tokens?



Yes. 1
Error: 400 {
  "error": {
    "message": "0 is less than the minimum of 1 - 'max_tokens'",
    "type": "invalid_request_error",
    "param": null,
    "code": null


import requests
import json
import os

# Ensure you have your OpenAI API key set in the environment variables
openai_api_key = os.getenv("OPENAI_API_KEY")
if openai_api_key is None:
    raise ValueError("OpenAI API key is not set in environment variables.")

url = ""

headers = {
    "Content-Type": "application/json",
    "Authorization": f"Bearer {openai_api_key}"

data = {
    "model": "gpt-3.5-turbo-1106",
    "max_tokens": 0,
    "messages": [
            "role": "system",
            "content": "You are a helpful assistant."
            "role": "user",
            "content": "Hello!"

response =, headers=headers, json=data)

# Check if the request was successful
if response.status_code == 200:
    print("Response from OpenAI:", response.json())
    print("Error:", response.status_code, response.text)
1 Like

While you can specify 1 token and get 1 token back, which is good for single token answers, and also evaluating that token’s probability, there is another limit you’ll find: functions.

When the AI emits functions, it needs enough tokens to write to the tool recipient with a well-formed beginning of a response that the internals of the API can parse. Otherwise you’ll get a 500 server error. About 12 tokens depending on the tool and function name length.

1 Like