# Record Token Usage After Streaming Object

When you're streaming structured data with [`streamObject`](/docs/reference/ai-sdk-core/stream-object),
you may want to record the token usage for billing purposes.

## `onFinish` Callback

You can use the `onFinish` callback to record token usage.
It is called when the stream is finished.

```ts file='index.ts' highlight={"15-17"}
import { streamObject } from 'ai';
import { z } from 'zod';

const result = streamObject({
  model: 'openai/gpt-4.1',
  schema: z.object({
    recipe: z.object({
      name: z.string(),
      ingredients: z.array(z.string()),
      steps: z.array(z.string()),
    }),
  }),
  prompt: 'Generate a lasagna recipe.',
  onFinish({ usage }) {
    console.log('Token usage:', usage);
  },
});
```

## `usage` Promise

The [`streamObject`](/docs/reference/ai-sdk-core/stream-object) result contains a `usage` promise that resolves to the total token usage.

```ts file='index.ts' highlight={"29,32"}
import { streamObject, TokenUsage } from 'ai';
import { z } from 'zod';

const result = streamObject({
  model: 'openai/gpt-4.1',
  schema: z.object({
    recipe: z.object({
      name: z.string(),
      ingredients: z.array(z.string()),
      steps: z.array(z.string()),
    }),
  }),
  prompt: 'Generate a lasagna recipe.',
});

// your custom function to record token usage:
function recordTokenUsage({
  inputTokens,
  outputTokens,
  totalTokens,
}: TokenUsage) {
  console.log('Prompt tokens:', inputTokens);
  console.log('Completion tokens:', outputTokens);
  console.log('Total tokens:', totalTokens);
}

// use as promise:
result.usage.then(recordTokenUsage);

// use with async/await:
recordTokenUsage(await result.usage);

// note: the stream needs to be consumed because of backpressure
for await (const partialObject of result.partialObjectStream) {
}
```


## Navigation

- [Generate Text](/v5/cookbook/node/generate-text)
- [Retrieval Augmented Generation](/v5/cookbook/node/retrieval-augmented-generation)
- [Knowledge Base Agent](/v5/cookbook/node/knowledge-base-agent)
- [Generate Text with Chat Prompt](/v5/cookbook/node/generate-text-with-chat-prompt)
- [Generate Text with Image Prompt](/v5/cookbook/node/generate-text-with-image-prompt)
- [Stream Text](/v5/cookbook/node/stream-text)
- [Stream Text with Chat Prompt](/v5/cookbook/node/stream-text-with-chat-prompt)
- [Stream Text with Image Prompt](/v5/cookbook/node/stream-text-with-image-prompt)
- [Stream Text with File Prompt](/v5/cookbook/node/stream-text-with-file-prompt)
- [Generate Object with a Reasoning Model](/v5/cookbook/node/generate-object-reasoning)
- [Generate Object](/v5/cookbook/node/generate-object)
- [Stream Object](/v5/cookbook/node/stream-object)
- [Stream Object with Image Prompt](/v5/cookbook/node/stream-object-with-image-prompt)
- [Record Token Usage After Streaming Object](/v5/cookbook/node/stream-object-record-token-usage)
- [Record Final Object after Streaming Object](/v5/cookbook/node/stream-object-record-final-object)
- [Call Tools](/v5/cookbook/node/call-tools)
- [Call Tools with Image Prompt](/v5/cookbook/node/call-tools-with-image-prompt)
- [Call Tools in Multiple Steps](/v5/cookbook/node/call-tools-multiple-steps)
- [Model Context Protocol (MCP) Tools](/v5/cookbook/node/mcp-tools)
- [Manual Agent Loop](/v5/cookbook/node/manual-agent-loop)
- [Web Search Agent](/v5/cookbook/node/web-search-agent)
- [Model Context Protocol (MCP) Elicitation](/v5/cookbook/node/mcp-elicitation)
- [Embed Text](/v5/cookbook/node/embed-text)
- [Embed Text in Batch](/v5/cookbook/node/embed-text-batch)
- [Intercepting Fetch Requests](/v5/cookbook/node/intercept-fetch-requests)
- [Local Caching Middleware](/v5/cookbook/node/local-caching-middleware)


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