Implementation:Openai Openai python Input Tokens Count

Knowledge Sources	openai-python OpenAI Responses API
Domains	Cost_Management, NLP
Last Updated	2026-02-15 00:00 GMT

Overview

Concrete tool for counting input tokens before sending a Responses API request provided by the OpenAI Python SDK.

Description

The InputTokens resource provides a count() method that accepts the same parameters as responses.create() and returns the total token count without generating a response. This enables cost estimation and context window validation.

Usage

Call client.responses.input_tokens.count() with the same input, model, tools, and instructions you would pass to responses.create().

Code Reference

Source Location

• Repository: openai-python
• File: src/openai/resources/responses/input_tokens.py

Signature

class InputTokens(SyncAPIResource):
    def count(
        self,
        *,
        input: Union[str, ResponseInputParam],
        model: ResponsesModel,
        tools: Iterable[ToolParam] | NotGiven = NOT_GIVEN,
        instructions: Optional[str] | NotGiven = NOT_GIVEN,
        # ... additional parameters matching responses.create
    ) -> InputTokenCountResponse:
        """
        Count the number of input tokens for a responses request.

        Returns:
            InputTokenCountResponse with total_tokens field.
        """

Import

from openai import OpenAI
# Access via client.responses.input_tokens.count()

I/O Contract

Inputs

Name	Type	Required	Description
input	Union[str, ResponseInputParam]	Yes	Same input as responses.create
model	ResponsesModel	Yes	Model ID for tokenization
tools	Iterable[ToolParam]	No	Tool definitions to include in count
instructions	str	No	System instructions to count

Outputs

Name	Type	Description
total_tokens	int	Total number of input tokens

Usage Examples

Basic Token Count

from openai import OpenAI

client = OpenAI()
result = client.responses.input_tokens.count(
    model="gpt-4o",
    input="How many tokens is this prompt?",
)
print(f"Input tokens: {result.total_tokens}")

Count with Tools and Instructions

result = client.responses.input_tokens.count(
    model="gpt-4o",
    input="Search for Python tutorials",
    instructions="You are a helpful coding assistant.",
    tools=[{"type": "web_search"}],
)
print(f"Total input tokens (with tools): {result.total_tokens}")

Pre-flight Validation

MAX_CONTEXT = 128000
DESIRED_OUTPUT = 4000

count = client.responses.input_tokens.count(
    model="gpt-4o",
    input=long_document,
)
if count.total_tokens > MAX_CONTEXT - DESIRED_OUTPUT:
    print("Input too long, truncating...")
    # Truncate and retry

Related Pages

Implements Principle

• Principle:Openai_Openai_python_Input_Token_Counting

Requires Environment

• Environment:Openai_Openai_python_Python_3_9_Plus