Gemini 3.1 Flash Tts

Name: Google Gemini 3.1 Flash Tts
Price: 0.05 USD
Availability: InStock
Author: Google

google/gemini-3.1-flash-tts

Gemini 3.1 Flash Tts by Google - convert text to natural-sounding speech with AI. Supports multiple voices, languages, emotions, and speaking styles for content creation and accessibility.

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Base price: $0.05USD / run
Execution: async
Model type: audio
Input fields: 7

Production route

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Playground

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Input

Prompt(string)

The text to convert to speech. Gemini 3.1 Flash TTS supports natural-language prompting for style, pace, accent, and emotional expression — include delivery instructions inline with the text (e.g. 'Say cheerfully: Have a wonderful day!'). Supports expressive audio tags like [sigh], [laughing], [whispering], [short pause] for fine-grained control over delivery. For multi-speaker synthesis, prefix lines with speaker aliases defined in the speakers field (e.g. 'Alice: Hello!\nBob: Hi!').

Output Format(string)

Audio output format. mp3: compressed, small file size (recommended). wav: uncompressed PCM wrapped in WAV (24 kHz, 16-bit mono). ogg_opus: Ogg container with Opus codec, good quality-to-size ratio. Allowed values: wav, mp3, ogg_opus.

Temperature(number)

Controls the randomness of the speech output. Higher values produce more creative and varied delivery, while lower values make the output more predictable and focused. Range: 0 to 2.

Speakers(array)

Multi-speaker voice configuration. When set, enables multi-speaker synthesis where different parts of the text are spoken by different voices. Each speaker needs a voice and a speaker_id (alias) that matches prefixes in the prompt.

Language Code(string)

Language for multilingual synthesis. When set, steers the model to speak in the specified language. If not set, the model auto-detects the language from the text. Allowed values: Arabic (Egypt), Bangla (Bangladesh), Dutch (Netherlands), English (India), English (US), French (France), German (Germany), Hindi (India), Indonesian (Indonesia), Italian (Italy), Japanese (Japan), Korean (South Korea), Marathi (India), Polish (Poland), Portuguese (Brazil), Romanian (Romania), Russian (Russia), Spanish (Spain), Tamil (India), Telugu (India), Thai (Thailand), Turkish (Turkey), Ukrainian (Ukraine), Vietnamese (Vietnam), Afrikaans (South Africa), Albanian (Albania), Amharic (Ethiopia), Arabic (World), Armenian (Armenia), Azerbaijani (Azerbaijan), Basque (Spain), Belarusian (Belarus), Bulgarian (Bulgaria), Burmese (Myanmar), Catalan (Spain), Cebuano (Philippines), Chinese Mandarin (China), Chinese Mandarin (Taiwan), Croatian (Croatia), Czech (Czech Republic), Danish (Denmark), English (Australia), English (UK), Estonian (Estonia), Filipino (Philippines), Finnish (Finland), French (Canada), Galician (Spain), Georgian (Georgia), Greek (Greece), Gujarati (India), Haitian Creole (Haiti), Hebrew (Israel), Hungarian (Hungary), Icelandic (Iceland), Javanese (Java), Kannada (India), Konkani (India), Lao (Laos), Latin (Vatican City), Latvian (Latvia), Lithuanian (Lithuania), Luxembourgish (Luxembourg), Macedonian (North Macedonia), Maithili (India), Malagasy (Madagascar), Malay (Malaysia), Malayalam (India), Mongolian (Mongolia), Nepali (Nepal), Norwegian Bokmal (Norway), Norwegian Nynorsk (Norway), Odia (India), Pashto (Afghanistan), Persian (Iran), Portuguese (Portugal), Punjabi (India), Serbian (Serbia), Sindhi (India), Sinhala (Sri Lanka), Slovak (Slovakia), Slovenian (Slovenia), Spanish (Latin America), Spanish (Mexico), Swahili (Kenya), Swedish (Sweden), Urdu (Pakistan).

Voice(string)

Voice preset for single-speaker synthesis. 30 distinct voices are available. Ignored when speakers is set. Popular choices: Kore (strong, firm female), Puck (upbeat, lively male), Charon (calm, professional male), Zephyr (bright, clear female), Aoede (warm, melodic female). Allowed values: Achernar, Achird, Algenib, Algieba, Alnilam, Aoede, Autonoe, Callirrhoe, Charon, Despina, Enceladus, Erinome, Fenrir, Gacrux, Iapetus, Kore, Laomedeia, Leda, Orus, Pulcherrima, Puck, Rasalgethi, Sadachbia, Sadaltager, Schedar, Sulafat, Umbriel, Vindemiatrix, Zephyr, Zubenelgenubi.

Style Instructions(string)

Optional style and delivery instructions prepended to the prompt. Controls expressiveness, accent, pace, tone, and emotional expression using natural language. Use this to separate style control from the text content. Examples: 'Speak warmly and slowly', 'Read this as a dramatic newscast', 'Use a British accent with a cheerful tone', 'Whisper mysteriously'.

OutputExample

Open original

Examples

Select an example to load its inputs and result into the playground.

Model card

Specifications

Pricing

Base price: $0.05 / run

Context & modalities

Input: Schema-defined
Output: audio

Capabilities

Chat: Not supported
Vision: Not supported
Reasoning: Not supported
Structured output: Not supported
Function calling: Not supported
Audio input: Not supported

Access

Provider: Google
Model ID: google/gemini-3.1-flash-tts
Execution: async
Base URL: https://api.sandbase.ai
API: Unified Run API
Endpoint: /v1/run

API README

Gemini 3.1 Flash Tts

Gemini 3.1 Flash TTS speaks text in dozens of languages with 30 prebuilt voices, and supports two-speaker dialogue through speakers. Steer tone and pace with style_instructions.

Fields

Field	Type	Default	Notes
`prompt`	string, required	—	Text to speak. For dialogue, prefix lines with the speaker names defined in `speakers`.
`output_format`	`wav` / `mp3` / `ogg_opus`	`mp3`	Output file format.
`temperature`	number 0–2	1	Higher values give more varied delivery.
`speakers`	object[]	—	Optional speaker-to-voice list for multi-speaker dialogue.
`language_code`	`Arabic (Egypt)` / `Bangla (Bangladesh)` / `Dutch (Netherlands)` / `English (India)` / `English (US)` / `French (France)` / `German (Germany)` / `Hindi (India)` / `Indonesian (Indonesia)` / `Italian (Italy)` / `Japanese (Japan)` / `Korean (South Korea)` / `Marathi (India)` / `Polish (Poland)` / `Portuguese (Brazil)` / `Romanian (Romania)` / `Russian (Russia)` / `Spanish (Spain)` / `Tamil (India)` / `Telugu (India)` / `Thai (Thailand)` / `Turkish (Turkey)` / `Ukrainian (Ukraine)` / `Vietnamese (Vietnam)` / `Afrikaans (South Africa)` / `Albanian (Albania)` / `Amharic (Ethiopia)` / `Arabic (World)` / `Armenian (Armenia)` / `Azerbaijani (Azerbaijan)` / `Basque (Spain)` / `Belarusian (Belarus)` / `Bulgarian (Bulgaria)` / `Burmese (Myanmar)` / `Catalan (Spain)` / `Cebuano (Philippines)` / `Chinese Mandarin (China)` / `Chinese Mandarin (Taiwan)` / `Croatian (Croatia)` / `Czech (Czech Republic)` / `Danish (Denmark)` / `English (Australia)` / `English (UK)` / `Estonian (Estonia)` / `Filipino (Philippines)` / `Finnish (Finland)` / `French (Canada)` / `Galician (Spain)` / `Georgian (Georgia)` / `Greek (Greece)` / `Gujarati (India)` / `Haitian Creole (Haiti)` / `Hebrew (Israel)` / `Hungarian (Hungary)` / `Icelandic (Iceland)` / `Javanese (Java)` / `Kannada (India)` / `Konkani (India)` / `Lao (Laos)` / `Latin (Vatican City)` / `Latvian (Latvia)` / `Lithuanian (Lithuania)` / `Luxembourgish (Luxembourg)` / `Macedonian (North Macedonia)` / `Maithili (India)` / `Malagasy (Madagascar)` / `Malay (Malaysia)` / `Malayalam (India)` / `Mongolian (Mongolia)` / `Nepali (Nepal)` / `Norwegian Bokmal (Norway)` / `Norwegian Nynorsk (Norway)` / `Odia (India)` / `Pashto (Afghanistan)` / `Persian (Iran)` / `Portuguese (Portugal)` / `Punjabi (India)` / `Serbian (Serbia)` / `Sindhi (India)` / `Sinhala (Sri Lanka)` / `Slovak (Slovakia)` / `Slovenian (Slovenia)` / `Spanish (Latin America)` / `Spanish (Mexico)` / `Swahili (Kenya)` / `Swedish (Sweden)` / `Urdu (Pakistan)`	—	Spoken language.
`voice`	`Achernar` / `Achird` / `Algenib` / `Algieba` / `Alnilam` / `Aoede` / `Autonoe` / `Callirrhoe` / `Charon` / `Despina` / `Enceladus` / `Erinome` / `Fenrir` / `Gacrux` / `Iapetus` / `Kore` / `Laomedeia` / `Leda` / `Orus` / `Pulcherrima` / `Puck` / `Rasalgethi` / `Sadachbia` / `Sadaltager` / `Schedar` / `Sulafat` / `Umbriel` / `Vindemiatrix` / `Zephyr` / `Zubenelgenubi`	`Kore`	Prebuilt voice for single-speaker requests.
`style_instructions`	string	—	How to say it.

Billing

$0.05 per started 1,000 characters of text.

Text	Price
200 characters	$0.05
1,000 characters	$0.05
2,500 characters	$0.15

Failed runs are not charged.

Prompting

For dialogue, write Name: line and map each name to a voice in speakers.

Also on SandBase

Related: google/gemini-3.8-flash-tts (newer, cheaper).

Start building

Send your first request

OpenAI-compatible endpoint with unified authentication and usage tracking.

Production API

Unified Run API endpoint

https://api.sandbase.ai/v1/run

Model ID

google/gemini-3.1-flash-tts

# The quoted heredoc keeps Unicode and shell metacharacters unchanged.
result=$(curl --fail-with-body --silent \
  -X POST "https://api.sandbase.ai/v1/run" \
  -H "Authorization: Bearer $SANDBASE_API_KEY" \
  -H "Content-Type: application/json" \
  --data-binary @- <<'SANDBASE_JSON'
{
  "model": "google/gemini-3.1-flash-tts",
  "voice": "Kore",
  "prompt": "I can't believe it worked! [laughing] After all those hours of debugging [sigh] it was just a missing semicolon.",
  "speakers": [
    {
      "voice": "Charon",
      "speaker_id": "Host"
    },
    {
      "voice": "Kore",
      "speaker_id": "DrChen"
    }
  ],
  "temperature": 1,
  "language_code": "English (US)",
  "output_format": "mp3",
  "style_instructions": "Say the following in a warm, conversational tone"
}
SANDBASE_JSON
)
run_id=$(printf '%s' "$result" | jq -r .id)
for attempt in $(seq 1 120); do
  status=$(printf '%s' "$result" | jq -r .status)
  case "$status" in completed|failed|timeout) break ;; esac
  sleep 2
  result=$(curl --fail-with-body --silent \
    -H "Authorization: Bearer $SANDBASE_API_KEY" \
    "https://api.sandbase.ai/v1/run/$run_id")
done
status=$(printf '%s' "$result" | jq -r .status)
[ "$status" = completed ] || { echo "Generation ended: $status" >&2; exit 1; }
printf '%s\n' "$result"

Choose your model

Compare models

All image & video models

Model	Type	Default price	Released
Gemini 3.1 Flash TtsThis model `Google`	Audio	$0.05 / run	Apr 16, 2026
Gemini 3.8 Flash TTS `Google`	Audio	$0.04 / run	Sep 25, 2026
Gemini 3.8 Flash Lite TTS `Google`	Audio	$0.03 / run	Sep 25, 2026
Lyria 3.5 `Google`	Audio	$0.10 / run	Sep 15, 2026

Questions

FAQ

How do I call Google Gemini 3.1 Flash Tts through SandBase?

Create a SandBase API key, then send requests with the model ID "google/gemini-3.1-flash-tts" to Unified Run API (/v1/run) at https://api.sandbase.ai. The request examples on this page show the exact payload.

Do I need a separate Google account?

No. One SandBase API key and balance gives you access to Google Gemini 3.1 Flash Tts and the other models in the catalog; you do not need to sign up with Google separately.