計算 Gemini 模型的符記和可計費的字元

生成式模型會將資料拆解成稱為「符記」的單元，以便處理。每個模型都有詞元數量上限，可在提示和回覆中處理。

本頁面說明如何使用 Count Tokens API，針對對 Gemini 模型提出的要求，取得預估的符號數量和可計費字元數。沒有 API 可在回應中取得符記的預估值。

請注意，Count Tokens API 無法用於 Imagen 模型。

計數提供哪些資訊？

請注意以下關於計算符記和計費字元的事項：

  • 計算總符記數

    • 這項計數有助於確保您的要求不會超過允許的上下文視窗。

    • 符記數量會反映大小，也就是所有要求輸入內容中提供的所有檔案 (例如圖片)。不會計算圖片數量或影片中的秒數。

    • 對於所有 Gemini 模型，符記相當於約 4 個字元。100 個符記約等於 60 到 80 個英文單字。

  • 計算總計費字元數

    • 這項計數有助於瞭解及控管費用，因為對於 Vertex AI，字元數是定價計算的一部分。

    • 可計費的字元數量會反映文字中提供的要求輸入內容字元數量。

對於較舊的 Gemini 模型，符記不是定價計算的一部分；但對於 Gemini 2.0 和 Gemini 2.5 模型，符記會用於定價計算。進一步瞭解每個模型的符記限制和每個模型的價格。

計算符號和計費字元的定價與配額

使用 CountTokens API 不需付費，也沒有配額限制。CountTokens API 的最高配額為每分鐘 3000 項要求 (RPM)。

程式碼範例

僅限文字輸入

Swift 

let response = try await model.countTokens("Write a story about a magic backpack.")
print("Total Tokens: \(response.totalTokens)")
print("Total Billable Characters: \(response.totalBillableCharacters)")

Kotlin 

val response = generativeModel.countTokens("Write a story about a magic backpack.")
println("Total Tokens: ${response.totalTokens}")
println("Total Billable Characters: ${response.totalBillableCharacters}")

Java 

Content prompt = new Content.Builder()
        .addText("Write a story about a magic backpack.")
        .build();

GenerativeModelFutures modelFutures = GenerativeModelFutures.from(model);
ListenableFuture countTokensResponse =
        modelFutures.countTokens(prompt);

Futures.addCallback(countTokensResponse, new FutureCallback() {
    @Override
    public void onSuccess(CountTokensResponse response) {
        System.out.println("Total Tokens = " + response.getTotalTokens());
        System.out.println("Total Billable Characters: = " +
                response.getTotalBillableCharacters());
    }

    @Override
    public void onFailure(Throwable t) {
        t.printStackTrace();
    }
}, executor);

Web 

const { totalTokens, totalBillableCharacters } = await model.countTokens("Write a story about a magic backpack.");
console.log(`Total tokens: ${totalTokens}, total billable characters: ${totalBillableCharacters}`);

Dart 

final tokenCount = await model.countTokens(Content.text("Write a story about a magic backpack."));
print('Token count: ${tokenCount.totalTokens}, billable characters: ${tokenCount.totalBillableCharacters}');

Unity 

var response = await model.CountTokensAsync("Write a story about a magic backpack.");
UnityEngine.Debug.Log($"Total Tokens: {response.TotalTokens}");
UnityEngine.Debug.Log($"Total Billable Characters: {response.TotalBillableCharacters}");

多模態輸入內容

Swift 

let response = try await model.countTokens(image, "What's in this picture?")
print("Total Tokens: \(response.totalTokens)")
print("Total Billable Characters: \(response.totalBillableCharacters)")

Kotlin 

val prompt = content {
  image(bitmap)
  text("What's in this picture?")
}
val response = generativeModel.countTokens(prompt)
println("Total Tokens: ${response.totalTokens}")
println("Total Billable Characters: ${response.totalBillableCharacters}")

Java 

Content prompt = new Content.Builder()
        .addImage(bitmap)
        .addText("What's in this picture?")
        .build();

GenerativeModelFutures modelFutures = GenerativeModelFutures.from(model);
ListenableFuture countTokensResponse =
        modelFutures.countTokens(prompt);

Futures.addCallback(countTokensResponse, new FutureCallback() {
    @Override
    public void onSuccess(CountTokensResponse response) {
        System.out.println("Total Tokens = " + response.getTotalTokens());
        System.out.println("Total Billable Characters: = " +
                response.getTotalBillableCharacters());
    }

    @Override
    public void onFailure(Throwable t) {
        t.printStackTrace();
    }
}, executor);

Web 

const prompt = "What's in this picture?";
const imagePart = { inlineData: { mimeType: 'image/jpeg', data: imageAsBase64 }};

const { totalTokens, totalBillableCharacters } = await model.countTokens([prompt, imagePart]);
console.log(`Total tokens: ${totalTokens}, total billable characters: ${totalBillableCharacters}`);

Dart 

final prompt = TextPart("What's in the picture?");
final tokenCount = await model.countTokens([
  Content.multi([prompt, imagePart])
]);
print('Token count: ${tokenCount.totalTokens}, billable characters: ${tokenCount.totalBillableCharacters}');

Unity 

var response = await model.CountTokensAsync(new [] {
  ModelContent.Text("What's in this picture?"),
  ModelContent.InlineData("image/png", imageData)
});
UnityEngine.Debug.Log($"Total Tokens: {response.TotalTokens}");
UnityEngine.Debug.Log($"Total Billable Characters: {response.TotalBillableCharacters}");