Gemini 2.5 Flash TTS API

Low-latency text-to-speech with single- and multi-speaker voices and controllable style, accent, and expressive tone for production apps.

GoogleAudio GenerationProprietary Endpoint

About Gemini 2.5 Flash TTS

Low-latency text-to-speech with single- and multi-speaker voices and controllable style, accent, and expressive tone for production apps.

Also known as Gemini Flash TTS, Gemini-2.5-Flash-TTS

Gemini 2.5 Flash TTS specs

Model ID
gemini-2-5-flash-tts
Provider
Google
Category
Audio Generation
Input
text
Output
audio
Endpoints
POST /v1/audio/speech

Gemini 2.5 Flash TTS API pricing

Live pay-as-you-go rates from the EmpirioLabs catalog. You are billed only for what you use, with no monthly minimum.

Type
Spec
Rate
Input
per 1M prompt tokens
$1.50
Output
per 1M generated tokens
$30.00
Compare on the full pricing page

How to call the Gemini 2.5 Flash TTS API

Gemini 2.5 Flash TTS serves speech through POST /v1/audio/speech and returns playable audio. Send the text to speak as input with the model id gemini-2-5-flash-tts. Get an API key from the EmpirioLabs dashboard.

cURL
curl https://api.empiriolabs.ai/v1/audio/speech \
  -H "Authorization: Bearer $EMPIRIOLABS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "gemini-2-5-flash-tts",
    "input": "Welcome to EmpirioLabs. Your build just finished."
  }' \
  --output speech.mp3
Python
import requests

response = requests.post(
    "https://api.empiriolabs.ai/v1/audio/speech",
    headers={"Authorization": "Bearer YOUR_EMPIRIOLABS_API_KEY"},
    json={"model": "gemini-2-5-flash-tts", "input": "Welcome to EmpirioLabs."},
)
with open("speech.mp3", "wb") as f:
    f.write(response.content)
Full Gemini 2.5 Flash TTS API reference

Gemini 2.5 Flash TTS API parameters

Request parameters supported by the Gemini 2.5 Flash TTS API on EmpirioLabs. Defaults apply when a field is omitted.

ParameterTypeDefaultRange / valuesDescription
inputstring--Text to convert to speech. For multi-speaker mode, prefix lines with Speaker1: / Speaker2:.
modeenumsinglesingle, multisingle = one voice, multi = two-voice dialogue (uses voice + voice2 + speaker names).
languagestringen-US-BCP-47 language tag (en-US, es-ES, etc.) for pronunciation cues.
voiceenumCharonZephyr, Puck, Charon, Kore, Fenrir, Leda, Orus, Aoede, Callir...Primary voice name (e.g. Kore, Puck, Aoede). Leave blank for the default.
voice2enumKoreZephyr, Puck, Charon, Kore, Fenrir, Leda, Orus, Aoede, Callir...Second voice name for multi-speaker mode.
speaker1_namestringSpeaker1-Display name used in the input prefix for speaker 1 (default: Speaker1).
speaker2_namestringSpeaker2-Display name used in the input prefix for speaker 2 (default: Speaker2).
output_formatenumWAVWAV, MP3, OGG, ALAW, MULAWAudio file format (mp3, wav, opus, flac, etc.).
speednumber10.25 to 2Playback rate. 1.0 = natural; <1 slower, >1 faster.
volume_gainnumber0-96 to 16Output gain in dB. 0 = unchanged.
sample_rateenum240008000, 16000, 22050, 24000, 44100, 48000Output sample rate in Hz (8000, 16000, 24000, 44100, 48000).
style_promptstring--Natural-language style direction (e.g. "warm, conversational" or "newscaster, serious").

Good to know

Modes

  • Single speaker
  • Multi-speaker (max 2 voices) — text must be in SpeakerName: text format

Limits

  • Text + style prompt: 4,000 bytes each
  • Audio billing: ~32 tokens per second of generated audio (~10-15 chars/s)

Voices and languages

  • 30+ voice options across emotional/tonal characters
  • 24+ language locales supported

Output formats

  • MP3, WAV, OGG

Gemini 2.5 Flash TTS API: common questions

How much does the Gemini 2.5 Flash TTS API cost?

On EmpirioLabs, Gemini 2.5 Flash TTS is billed pay as you go: Input $1.50 per 1M prompt tokens; Output $30.00 per 1M generated tokens. The live rate card on this page always matches what the API charges.

Which endpoint does Gemini 2.5 Flash TTS use?

Gemini 2.5 Flash TTS is served through POST /v1/audio/speech on api.empiriolabs.ai with standard bearer-token authentication.

Can I try Gemini 2.5 Flash TTS in the browser before integrating?

Yes. The EmpirioLabs playground runs Gemini 2.5 Flash TTS in the browser with the same parameters the API exposes, so you can test prompts before writing code.

How do I get a Gemini 2.5 Flash TTS API key?

Create an EmpirioLabs account, then generate a key under API Keys in the dashboard. Billing is pay-as-you-go credits, so you only pay for the requests you make.

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