Use the Count Tokens API

This guide shows you how to get the token count and the number of billable characters for a prompt.

This page covers the following topics:

Choose a method to count tokens

You can get the token count for a prompt using either the countTokens API or the Vertex AI SDK for Python tokenizer. For most scenarios, using the SDK tokenizer is recommended. The following table compares the two methods.

Method Description Pros Cons
Vertex AI SDK for Python tokenizer An integrated tokenizer within the Python SDK that performs local token counting. For details, see List and count tokens. Fast (no network latency) and easy to integrate into Python workflows. This is the recommended method. Specific to the Python SDK.
countTokens API A REST API endpoint that returns the token count and billable characters for a prompt. Language-agnostic (works with any language that can make REST calls) and provides billable character count. Requires a network API call, which introduces latency.

Supported models

The following multimodal models support getting an estimate of the prompt token count:

To learn more about model versions, see Gemini model versions and lifecycle.

Get the token count for a prompt

You can get a token count estimate and the number of billable characters for a prompt by using the Vertex AI API.

Console

To get the token count for a prompt by using Vertex AI Studio in the Google Cloud console, do the following:

  1. In the Vertex AI section of the Google Cloud console, go to the Vertex AI Studio page.

    Go to Vertex AI Studio

  2. Click either Open Freeform or Open Chat.
  3. The number of tokens is calculated and displayed as you type in the Prompt pane. This count includes the number of tokens in any input files.
  4. To see more details, click <count> tokens to open the Prompt tokenizer.
    • To view the tokens in the text prompt, click Token ID to text. The tokens are highlighted with different colors to mark the boundary of each token ID. This view doesn't support media tokens.
    • To view the token IDs, click Token ID.

      To close the tokenizer tool pane, click X, or click outside of the pane.

Python

Install

pip install --upgrade google-genai

To learn more, see the SDK reference documentation.

Set environment variables to use the Gen AI SDK with Vertex AI: 

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values
# with appropriate values for your project.
export GOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECT
export GOOGLE_CLOUD_LOCATION=global
export GOOGLE_GENAI_USE_VERTEXAI=True
 

from google import genai
from google.genai.types import HttpOptions

client = genai.Client(http_options=HttpOptions(api_version="v1"))
response = client.models.count_tokens(
    model="gemini-2.5-flash",
    contents="What's the highest mountain in Africa?",
)
print(response)
# Example output:
# total_tokens=10
# cached_content_token_count=None

Go

Learn how to install or update the Go.

To learn more, see the SDK reference documentation.

Set environment variables to use the Gen AI SDK with Vertex AI: 

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values
# with appropriate values for your project.
export GOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECT
export GOOGLE_CLOUD_LOCATION=global
export GOOGLE_GENAI_USE_VERTEXAI=True
 

import (
	"context"
	"fmt"
	"io"

	genai "google.golang.org/genai"
)

// countWithTxt shows how to count tokens with text input.
func countWithTxt(w io.Writer) error {
	ctx := context.Background()

	client, err := genai.NewClient(ctx, &genai.ClientConfig{
		HTTPOptions: genai.HTTPOptions{APIVersion: "v1"},
	})
	if err != nil {
		return fmt.Errorf("failed to create genai client: %w", err)
	}

	modelName := "gemini-2.5-flash"
	contents := []*genai.Content{
		{Parts: []*genai.Part{
			{Text: "What's the highest mountain in Africa?"},
		}},
	}

	resp, err := client.Models.CountTokens(ctx, modelName, contents, nil)
	if err != nil {
		return fmt.Errorf("failed to generate content: %w", err)
	}

	fmt.Fprintf(w, "Total: %d\nCached: %d\n", resp.TotalTokens, resp.CachedContentTokenCount)

	// Example response:
	// Total: 9
	// Cached: 0

	return nil
}

Node.js

Install

npm install @google/genai

To learn more, see the SDK reference documentation.

Set environment variables to use the Gen AI SDK with Vertex AI: 

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values
# with appropriate values for your project.
export GOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECT
export GOOGLE_CLOUD_LOCATION=global
export GOOGLE_GENAI_USE_VERTEXAI=True
 

const {GoogleGenAI} = require('@google/genai');

const GOOGLE_CLOUD_PROJECT = process.env.GOOGLE_CLOUD_PROJECT;
const GOOGLE_CLOUD_LOCATION = process.env.GOOGLE_CLOUD_LOCATION || 'global';

async function countTokens(
  projectId = GOOGLE_CLOUD_PROJECT,
  location = GOOGLE_CLOUD_LOCATION
) {
  const ai = new GoogleGenAI({
    vertexai: true,
    project: projectId,
    location: location,
  });

  const response = await ai.models.countTokens({
    model: 'gemini-2.5-flash',
    contents: 'What is the highest mountain in Africa?',
  });

  console.log(response);

  return response.totalTokens;
}

Java

Learn how to install or update the Java.

To learn more, see the SDK reference documentation.

Set environment variables to use the Gen AI SDK with Vertex AI: 

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values
# with appropriate values for your project.
export GOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECT
export GOOGLE_CLOUD_LOCATION=global
export GOOGLE_GENAI_USE_VERTEXAI=True
 


import com.google.genai.Client;
import com.google.genai.types.CountTokensResponse;
import com.google.genai.types.HttpOptions;
import java.util.Optional;

public class CountTokensWithText {

  public static void main(String[] args) {
    // TODO(developer): Replace these variables before running the sample.
    String modelId = "gemini-2.5-flash";
    countTokens(modelId);
  }

  // Counts tokens with text input
  public static Optional<Integer> countTokens(String modelId) {
    // Initialize client that will be used to send requests. This client only needs to be created
    // once, and can be reused for multiple requests.
    try (Client client =
        Client.builder()
            .location("global")
            .vertexAI(true)
            .httpOptions(HttpOptions.builder().apiVersion("v1").build())
            .build()) {

      CountTokensResponse response =
          client.models.countTokens(modelId, "What's the highest mountain in Africa?", null);

      System.out.print(response);
      // Example response:
      // CountTokensResponse{totalTokens=Optional[9], cachedContentTokenCount=Optional.empty}
      return response.totalTokens();
    }
  }
}

REST

To get the token count and the number of billable characters for a prompt by using the Vertex AI API, send a POST request to the publisher model endpoint.

Before using any of the request data, make the following replacements:

  • LOCATION: The region to process the request. Available options include the following:

    Click to expand a partial list of available regions

    • us-central1
    • us-west4
    • northamerica-northeast1
    • us-east4
    • us-west1
    • asia-northeast3
    • asia-southeast1
    • asia-northeast1
  • PROJECT_ID: Your project ID.
  • MODEL_ID: The model ID of the multimodal model that you want to use.
  • ROLE: The role in a conversation associated with the content. Specifying a role is required even in singleturn use cases. Acceptable values include the following:
    • USER: Specifies content that's sent by you.
  • TEXT: The text instructions to include in the prompt.

HTTP method and URL: 

POST https://LOCATION-aiplatform.googleapis.com/v1/projects/PROJECT_ID/locations/LOCATION/publishers/google/models/MODEL_ID:countTokens

Request JSON body: 

{
  "contents": [{
    "role": "ROLE",
    "parts": [{
      "text": "TEXT"
    }]
  }]
}

To send your request, choose one of these options:

curl

Save the request body in a file named request.json, and execute the following command: 

curl -X POST \
     -H "Authorization: Bearer $(gcloud auth print-access-token)" \
     -H "Content-Type: application/json; charset=utf-8" \
     -d @request.json \
     "https://LOCATION-aiplatform.googleapis.com/v1/projects/PROJECT_ID/locations/LOCATION/publishers/google/models/MODEL_ID:countTokens"

PowerShell

Save the request body in a file named request.json, and execute the following command: 

$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }

Invoke-WebRequest `
    -Method POST `
    -Headers $headers `
    -ContentType: "application/json; charset=utf-8" `
    -InFile request.json `
    -Uri "https://LOCATION-aiplatform.googleapis.com/v1/projects/PROJECT_ID/locations/LOCATION/publishers/google/models/MODEL_ID:countTokens" | Select-Object -Expand Content

You should receive a JSON response similar to the following.

Example for text with image or video

Python

Install

pip install --upgrade google-genai

To learn more, see the SDK reference documentation.

Set environment variables to use the Gen AI SDK with Vertex AI: 

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values
# with appropriate values for your project.
export GOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECT
export GOOGLE_CLOUD_LOCATION=global
export GOOGLE_GENAI_USE_VERTEXAI=True
 

from google import genai
from google.genai.types import HttpOptions, Part

client = genai.Client(http_options=HttpOptions(api_version="v1"))

contents = [
    Part.from_uri(
        file_uri="gs://cloud-samples-data/generative-ai/video/pixel8.mp4",
        mime_type="video/mp4",
    ),
    "Provide a description of the video.",
]

response = client.models.count_tokens(
    model="gemini-2.5-flash",
    contents=contents,
)
print(response)
# Example output:
# total_tokens=16252 cached_content_token_count=None

Go

Learn how to install or update the Go.

To learn more, see the SDK reference documentation.

Set environment variables to use the Gen AI SDK with Vertex AI: 

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values
# with appropriate values for your project.
export GOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECT
export GOOGLE_CLOUD_LOCATION=global
export GOOGLE_GENAI_USE_VERTEXAI=True
 

import (
	"context"
	"fmt"
	"io"

	genai "google.golang.org/genai"
)

// countWithTxtAndVid shows how to count tokens with text and video inputs.
func countWithTxtAndVid(w io.Writer) error {
	ctx := context.Background()

	client, err := genai.NewClient(ctx, &genai.ClientConfig{
		HTTPOptions: genai.HTTPOptions{APIVersion: "v1"},
	})
	if err != nil {
		return fmt.Errorf("failed to create genai client: %w", err)
	}

	modelName := "gemini-2.5-flash"
	contents := []*genai.Content{
		{Parts: []*genai.Part{
			{Text: "Provide a description of the video."},
			{FileData: &genai.FileData{
				FileURI:  "gs://cloud-samples-data/generative-ai/video/pixel8.mp4",
				MIMEType: "video/mp4",
			}},
		},
			Role: "user"},
	}

	resp, err := client.Models.CountTokens(ctx, modelName, contents, nil)
	if err != nil {
		return fmt.Errorf("failed to generate content: %w", err)
	}

	fmt.Fprintf(w, "Total: %d\nCached: %d\n", resp.TotalTokens, resp.CachedContentTokenCount)

	// Example response:
	// Total: 16252
	// Cached: 0

	return nil
}

Node.js

Install

npm install @google/genai

To learn more, see the SDK reference documentation.

Set environment variables to use the Gen AI SDK with Vertex AI: 

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values
# with appropriate values for your project.
export GOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECT
export GOOGLE_CLOUD_LOCATION=global
export GOOGLE_GENAI_USE_VERTEXAI=True
 

const {GoogleGenAI} = require('@google/genai');

const GOOGLE_CLOUD_PROJECT = process.env.GOOGLE_CLOUD_PROJECT;
const GOOGLE_CLOUD_LOCATION = process.env.GOOGLE_CLOUD_LOCATION || 'global';

async function countTokens(
  projectId = GOOGLE_CLOUD_PROJECT,
  location = GOOGLE_CLOUD_LOCATION
) {
  const ai = new GoogleGenAI({
    vertexai: true,
    project: projectId,
    location: location,
  });

  const video = {
    fileData: {
      fileUri: 'gs://cloud-samples-data/generative-ai/video/pixel8.mp4',
      mimeType: 'video/mp4',
    },
  };

  const response = await ai.models.countTokens({
    model: 'gemini-2.5-flash',
    contents: [video, 'Provide a description of the video.'],
  });

  console.log(response);

  return response.totalTokens;
}

Java

Learn how to install or update the Java.

To learn more, see the SDK reference documentation.

Set environment variables to use the Gen AI SDK with Vertex AI: 

# Replace the `GOOGLE_CLOUD_PROJECT` and `GOOGLE_CLOUD_LOCATION` values
# with appropriate values for your project.
export GOOGLE_CLOUD_PROJECT=GOOGLE_CLOUD_PROJECT
export GOOGLE_CLOUD_LOCATION=global
export GOOGLE_GENAI_USE_VERTEXAI=True
 


import com.google.genai.Client;
import com.google.genai.types.Content;
import com.google.genai.types.CountTokensResponse;
import com.google.genai.types.HttpOptions;
import com.google.genai.types.Part;
import java.util.List;
import java.util.Optional;

public class CountTokensWithTextAndVideo {

  public static void main(String[] args) {
    // TODO(developer): Replace these variables before running the sample.
    String modelId = "gemini-2.5-flash";
    countTokens(modelId);
  }

  // Counts tokens with text and video inputs
  public static Optional<Integer> countTokens(String modelId) {
    // Initialize client that will be used to send requests. This client only needs to be created
    // once, and can be reused for multiple requests.
    try (Client client =
        Client.builder()
            .location("global")
            .vertexAI(true)
            .httpOptions(HttpOptions.builder().apiVersion("v1").build())
            .build()) {

      Content content =
          Content.fromParts(
              Part.fromText("Provide a description of this video"),
              Part.fromUri("gs://cloud-samples-data/generative-ai/video/pixel8.mp4", "video/mp4"));

      CountTokensResponse response = client.models.countTokens(modelId, List.of(content), null);

      System.out.print(response);
      // Example response:
      // CountTokensResponse{totalTokens=Optional[16707], cachedContentTokenCount=Optional.empty}
      return response.totalTokens();
    }
  }
}

REST

To get the token count and the number of billable characters for a prompt by using the Vertex AI API, send a POST request to the publisher model endpoint.

MODEL_ID="gemini-2.5-flash"
PROJECT_ID="my-project"
TEXT="Provide a summary with about two sentences for the following article."
REGION="us-central1"

curl \
-X POST \
-H "Authorization: Bearer $(gcloud auth print-access-token)" \
-H "Content-Type: application/json" \
https://${REGION}-aiplatform.googleapis.com/v1/projects/${PROJECT_ID}/locations/${REGION}/publishers/google/models/${MODEL_ID}:countTokens -d \
$'{
    "contents": [{
      "role": "user",
      "parts": [
        {
          "file_data": {
            "file_uri": "gs://cloud-samples-data/generative-ai/video/pixel8.mp4",
            "mime_type": "video/mp4"
          }
        },
        {
          "text": "'"$TEXT"'"
        }]
    }]
 }'

Pricing and quota

There is no charge for using the CountTokens API. The maximum quota for this API is 3,000 requests per minute.

What's next