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Gemini 2.5 Flash Lite Preview 09-2025

Gemini 2.5 Flash Lite Preview 09-2025 is Google's September 2025 preview of the next Flash Lite generation, delivering better instruction following, up to 50% fewer output tokens, and improved multimodal understanding including audio transcription and image analysis.

File InputReasoningTool UseVision (Image)Web SearchImplicit Caching
index.ts
import { streamText } from 'ai'


const result = streamText({
  model: 'google/gemini-2.5-flash-lite-preview-09-2025',
  prompt: 'Why is the sky blue?'
})
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Frequently Asked Questions

  • What improved in Gemini 2.5 Flash Lite Preview 09-2025 compared to the stable Flash Lite?

    Three areas: instruction following for complex prompts, output verbosity (up to 50% fewer tokens), and multimodal capabilities including audio transcription, image understanding, and translation.

  • Is Gemini 2.5 Flash Lite Preview 09-2025 a stable release?

    No. It's a preview release for developer feedback. Google provides a two-week deprecation notice before rotating preview models. Pin to the explicit model string if you need consistent behavior.

  • How much does the reduced verbosity save on cost?

    Rates are listed on this page. They reflect the providers routing through AI Gateway and shift when providers update their pricing.

  • Does Gemini 2.5 Flash Lite Preview 09-2025 generate images or audio?

    No. Like the stable Flash Lite, this model accepts multimodal inputs (text, images, audio, documents) but produces text output only.

  • How do I authenticate requests to Gemini 2.5 Flash Lite Preview 09-2025 through AI Gateway?

    Use a Vercel API key or OIDC token with AI Gateway. Use the identifier google/gemini-2.5-flash-lite-preview-09-2025 in your requests. AI Gateway handles provider routing and failover.

  • What is the -latest alias system?

    Google introduced aliases like gemini-flash-lite-latest that automatically point to the newest preview. These rotate with two-week deprecation notices. Use explicit model strings for reproducibility.

  • Should I migrate from stable Flash Lite to this preview?

    Evaluate it in a staging environment first. The preview improves instruction following and reduces token usage, but behavior may change before it reaches stable. Use AI Gateway's observability to compare quality and cost side by side.