Which should you pick?
Gemini 3.1 Flash TTS costs 12 credits (headline rate) and Cartesia Sonic 3.5 costs 4 credits (headline rate). One of the two does not publish what a full job costs, only a headline rate, so these two figures are not a like-for-like price comparison.
Gemini 3.1 Flash TTS holds the stronger leaderboard position (#9 in text to audio against #11 in text to audio). Those are two different leaderboards unless the category matches — Versely ranks each capability separately.
What a job costs
Gemini 3.1 Flash TTS
12 credits (headline rate)
It bills per 1,000 characters of input text.
- per 1,000 characters12 credits
Cartesia Sonic 3.5
4 credits (headline rate)
It bills per 1,000 characters of input text.
- per 1,000 characters4 credits
All figures are Versely credits. Your plan's credit allowance is on the pricing page.
Spec comparison
| Spec | Gemini 3.1 Flash TTS | Cartesia Sonic 3.5 |
|---|---|---|
| Provider | Cartesia | |
| Cost per job | 12 credits (headline rate) | 4 credits (headline rate) |
| Billing | per 1,000 characters of input text | per 1,000 characters of input text |
| Max resolution | — | — |
| Aspect ratios | — | — |
| Durations | — | — |
| Frame rates | — | — |
| Qualities | — | — |
| Requires starting image | No | No |
| Accepts video input | No | No |
| Reference images | — | — |
| Leaderboard | #9 in text to audio | #11 in text to audio |
| Released | Apr 14, 2026 | Jun 15, 2026 |
What each one does that the other doesn't
Only Gemini 3.1 Flash TTS
expressive, audio tags, multi speaker, 30 voices
Only Cartesia Sonic 3.5
voice clone, voice clone, emotion control, speed control, high quality, top ranked
Both list: text to audio, text to speech, multilingual.
Leaderboard positions
Versely ranks each capability on its own leaderboard, so a position is only comparable between two models within the same row.
Gemini 3.1 Flash TTS
- Text to audio#9
Cartesia Sonic 3.5
- Text to audio#11
Full Gemini 3.1 Flash TTS spec sheet →
Google Gemini 3.1 Flash TTS — expressive text-to-speech with 30 voices, natural-language style control, inline audio tags ([sigh], [laughing], [whispering]), multilingual synthesis, and multi-speaker dialogue.
Full Cartesia Sonic 3.5 spec sheet →
Cartesia's newest and top-ranked TTS model (Sonic 3.5). Multilingual, highly expressive, with emotion control, speed tuning, and voice cloning.
More comparisons
Frequently asked questions
Which is cheaper, Gemini 3.1 Flash TTS or Cartesia Sonic 3.5?+
They are not directly comparable on price: Gemini 3.1 Flash TTS costs 12 credits (headline rate) and Cartesia Sonic 3.5 costs 4 credits (headline rate), and one of those is a headline rate rather than the cost of a complete job.
What can Gemini 3.1 Flash TTS do that Cartesia Sonic 3.5 can't, or vice versa?+
Only Gemini 3.1 Flash TTS lists expressive, audio tags, multi speaker, 30 voices. Only Cartesia Sonic 3.5 lists voice clone, voice clone, emotion control, speed control, high quality, top ranked. Both list text to audio, text to speech, multilingual.
How do Gemini 3.1 Flash TTS and Cartesia Sonic 3.5 bill?+
Gemini 3.1 Flash TTS bills per 1,000 characters of input text. Cartesia Sonic 3.5 bills per 1,000 characters of input text. Both are charged in Versely credits.
Which ranks higher, Gemini 3.1 Flash TTS or Cartesia Sonic 3.5?+
Gemini 3.1 Flash TTS sits at #9 in text to audio and Cartesia Sonic 3.5 at #11 in text to audio on Versely's live model rankings. Versely ranks each capability on its own leaderboard, so those positions are only a direct comparison when the category is the same.
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