Google TTS Chirp 3 HD vs TTS-1 HD
Which one, when — curated verdict, not a benchmark table
Both charge $30 per million characters and both stream, so the split is control and length: google-tts-chirp3-hd takes 5000 bytes per request, exposes numeric voice parameters and lists SSML in preview, while tts-1-hd takes 4096 characters and offers no voice control at all. Coverage is broad on both, though tts-1-hd's list follows the Whisper language set rather than an enumerated locale list. Pick google-tts-chirp3-hd when you need to shape the delivery, tts-1-hd when the default voice is fine.
Pricing
| Google TTS Chirp 3 HD | TTS-1 HD | Δ | |
|---|---|---|---|
| Per 1M characters | $30 | $30 | = |
Rates from the live catalog at build time; each model page carries the current card.
Where they sit — price per 1M characters across all 7 text-to-speech models on this billing unit (log scale)
Capabilities
| Google TTS Chirp 3 HD | TTS-1 HD | |
|---|---|---|
| Streaming | yes | yes |
| SSML | preview | undocumented |
| Billing unit | character | character |
Specs
| Google TTS Chirp 3 HD | TTS-1 HD | |
|---|---|---|
| Input modalities | text | text |
| Output modalities | audio | audio |
| Request limit | 5000 bytes | 4096 characters |
| Voices | Voices are named after stars and published with a gender: 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 and Zubenelgenubi. A locale prefix forms the id, e.g. en-US-Chirp3-HD-Charon. Google describes the set as 30 distinct styles across many languages. | alloy, ash, coral, echo, fable, onyx, nova, sage and shimmer, a smaller set than the full 13-voice TTS list, and voices are currently optimized for English. |
| Languages | ar-XA, bn-IN, bg-BG, yue-HK, hr-HR, cs-CZ, da-DK, nl-BE, nl-NL, en-AU, en-IN, en-GB, en-US, et-EE, fi-FI, fr-CA, fr-FR, de-DE, el-GR, gu-IN, he-IL, hi-IN, hu-HU, id-ID, it-IT, ja-JP, kn-IN, ko-KR, lv-LV, lt-LT, ml-IN, cmn-CN, mr-IN, nb-NO, pl-PL, pt-BR, pa-IN, ro-RO, ru-RU, sr-RS, sk-SK, sl-SI, es-ES, es-US, sw-KE, sv-SE, ta-IN, te-IN, th-TH, tr-TR, uk-UA, ur-IN and vi-VN. | Generally follows the Whisper model’s language support: Afrikaans, Arabic, Armenian, Azerbaijani, Belarusian, Bosnian, Bulgarian, Catalan, Chinese, Croatian, Czech, Danish, Dutch, English, Estonian, Finnish, French, Galician, German, Greek, Hebrew, Hindi, Hungarian, Icelandic, Indonesian, Italian, Japanese, Kannada, Kazakh, Korean, Latvian, Lithuanian, Macedonian, Malay, Marathi, Maori, Nepali, Norwegian, Persian, Polish, Portuguese, Romanian, Russian, Serbian, Slovak, Slovenian, Spanish, Swahili, Swedish, Tagalog, Tamil, Thai, Turkish, Ukrainian, Urdu, Vietnamese and Welsh, despite voices being optimized for English |
| Voice control |
| none |
| Limits | Content limit of 5,000 total bytes per synthesize request. Default response format LINEAR16 streaming supports ALAW, MULAW, OGG_OPUS and PCM, batch adds MP3, so MP3 is not available on the streaming path. The only voice type Google's comparison table marks as streaming-capable. Generally available in the global, us and eu endpoints plus asia-southeast1, europe-west2 and asia-northeast1, but out of scope for regionalization and data residency. Billed per character including spaces and newlines, with all SSML tags except <mark> counted. | Speech generation endpoint (v1/audio/speech) only, with Chat Completions, Responses, Realtime, Batch and Fine-tuning all listed as not supported input text is capped at 4096 characters output mp3 (default), opus, aac, flac, wav or pcm (raw 24 kHz 16-bit signed little-endian samples) realtime playback via chunked transfer encoding |
Specs are transcribed from each vendor’s documentation; a row a vendor does not publish is left out rather than inferred. Full sources: Google TTS Chirp 3 HD · TTS-1 HD
Switch between them with one line
Both ids are in every tab below — the highlighted pair of lines is the only edit. Same endpoint, same key, same request shape.
from openai import OpenAI
client = OpenAI(
base_url="https://synthorai.io/v1",
api_key="sk-syn-...",
)
resp = client.audio.transcriptions.create(
model="google-tts-chirp3-hd",
# model="tts-1-hd", # uncomment this line, comment the one above
file=open("meeting.mp3", "rb"),
language="en",
)
print(resp.text)import OpenAI from "openai";
import fs from "node:fs";
const client = new OpenAI({
baseURL: "https://synthorai.io/v1",
apiKey: "sk-syn-...",
});
const resp = await client.audio.transcriptions.create({
model: "google-tts-chirp3-hd",
// model: "tts-1-hd", // uncomment this line, comment the one above
file: fs.createReadStream("meeting.mp3"),
});
console.log(resp.text);curl https://synthorai.io/v1/audio/transcriptions \
-H "Authorization: Bearer sk-syn-..." \
-F model="google-tts-chirp3-hd" \
# -F model="tts-1-hd" \ # uncomment this line, comment the one above
-F file=@meeting.mp3package main
import (
"context"
"fmt"
"os"
"github.com/openai/openai-go/v3"
"github.com/openai/openai-go/v3/option"
)
func main() {
client := openai.NewClient(
option.WithBaseURL("https://synthorai.io/v1"),
option.WithAPIKey("sk-syn-..."),
)
f, _ := os.Open("meeting.mp3")
resp, _ := client.Audio.Transcriptions.New(context.TODO(), openai.AudioTranscriptionNewParams{
Model: "google-tts-chirp3-hd",
// Model: "tts-1-hd", // uncomment this line, comment the one above
File: f,
})
fmt.Println(resp.Text)
}import com.openai.client.OpenAIClient;
import com.openai.client.okhttp.OpenAIOkHttpClient;
import com.openai.models.audio.transcriptions.*;
import java.nio.file.Paths;
OpenAIClient client = OpenAIOkHttpClient.builder()
.baseUrl("https://synthorai.io/v1")
.apiKey("sk-syn-...")
.build();
Transcription resp = client.audio().transcriptions().create(
TranscriptionCreateParams.builder()
.model("google-tts-chirp3-hd")
// .model("tts-1-hd") // uncomment this line, comment the one above
.file(Paths.get("meeting.mp3"))
.build()).asTranscription();
System.out.println(resp.text());FAQ
Which is cheaper, Google TTS Chirp 3 HD or TTS-1 HD?
They list the same per 1m characters ($30), so price does not decide this one — see the specs and capabilities below.
Can I A/B test Google TTS Chirp 3 HD against TTS-1 HD without two integrations?
Yes. Both are served through the same OpenAI-compatible endpoint with one API key — switching is a one-line model-string change, so you can route a fraction of traffic to each and compare bills directly.
How is text-to-speech billed?
Per character of input text, with a per-request character ceiling shown in the spec table. Long scripts must be chunked across requests on either model.