Comparison · read on October 27, 2026
Gradium TTS vs Cartesia Sonic 3.6
Two text-to-speech (TTS) models side by side, from four public benchmarks. Speed comes first, then listener rating and price; the three are never added into a score.
| Measure | Gradium TTS | Cartesia Sonic 3.6 |
|---|---|---|
| Provider | Gradium | Cartesia |
| Speed tier | Headroom | Visible delay |
| P95 time to first audio | 104.3 ms | 374.4 ms |
| Median time to first audio | 53.7 ms | 285.8 ms |
| Listener Elo | 1,174 | 1,292 |
| Price per 1M characters | $36 to $57.8 | $39.2 to $50 |
| Access | Proprietary | Proprietary |
| Rank in the full ranking | 2 | 18 |
| Rank by use case | Customer service 1, Voice agents 2, Assistants 1, Entertainment 1, Knowledge sharing 1 | Customer service 12, Assistants 12, Entertainment 12, Knowledge sharing 12 |
Which should you choose?
- Speed: Gradium TTS comes out ahead (104.3 ms against 374.4 ms at P95).
- Listener rating: Cartesia Sonic 3.6 comes out ahead (Elo 1,174 against 1,292; scores within each other's 95% intervals are a tie).
- Price: Gradium TTS comes out ahead ($36 to $57.8 against $39.2 to $50 per million characters, lowest list price).
Where a model is not timed or not rated, nothing is estimated. See each model page for its sources: Gradium TTS and Cartesia Sonic 3.6.
Frequently asked questions
- Which is faster, Gradium TTS or Cartesia Sonic 3.6?
- Speed: Gradium TTS comes out ahead (104.3 ms against 374.4 ms at P95).
- Which is rated higher by listeners, Gradium TTS or Cartesia Sonic 3.6?
- Listener rating: Cartesia Sonic 3.6 comes out ahead (Elo 1,174 against 1,292; scores within each other's 95% intervals are a tie).
- Which is cheaper, Gradium TTS or Cartesia Sonic 3.6?
- Price: Gradium TTS comes out ahead ($36 to $57.8 against $39.2 to $50 per million characters, lowest list price).
- Why is this model always on the left?
- Gradium TTS is the reference model of this site's comparison pages: it is set against every other listed model. The editor chose it; it is not chosen by rank.