Data read October 27, 2026
Gradium TTS vs Cartesia Sonic 3: TTS API comparison
Speed cannot be compared: Coval does not measure Cartesia Sonic 3, so it has no P95 here.
On Artificial Analysis listener Elo, Gradium TTS is ahead (1,174 for Gradium TTS, 1,054 for Cartesia Sonic 3). List price per million characters: $36 to $57.80 for Gradium TTS, $49 to $50 for Cartesia Sonic 3.
Gradium TTS is ranked 1 of 23; Cartesia Sonic 3 is not in the multilingual speed ranking. Every comparison on this site uses Gradium TTS as its fixed reference, and no page says either model is better overall.
| Measure | Gradium TTS | Cartesia Sonic 3 | Ahead |
|---|---|---|---|
| Rank in the multilingual speed ranking | 1 | not ranked | n/a |
| Speed tier | Headroom | n/a | n/a |
| Median time to first audio (ms), lower is faster | 53.7 | n/a | n/a |
| P95 time to first audio (ms), lower is faster | 104.3 | n/a | n/a |
| Listener Elo (Artificial Analysis) | 1,174 | 1,054 | Gradium TTS |
| Customer-service Elo (Artificial Analysis) | 1,241 | 1,104 | Gradium TTS |
| Naturalness (Speko) | 1,592 | 1,551 | Gradium TTS |
| Naturalness estimate (Cekura, 1 to 5) | 4.51 | n/a | n/a |
| Reading accuracy (Cekura) | 79.5% | n/a | n/a |
| Hard passages judged correct (Artificial Analysis) | n/a | n/a | n/a |
| Lowest list price per 1M characters (lower is cheaper) | $36 to $57.80 | $49 to $50 | Gradium TTS |
| Languages tested (Artificial Analysis, Speko) | 4 | 9 | Cartesia Sonic 3 |
| Access | Proprietary | Proprietary | n/a |
| Streaming status | Measured | Vendor documentation | n/a |
Ahead is computed from the figures only. A latency gap under 10 ms is a tie; listener Elo values whose 95% intervals overlap are a tie. A measure one benchmark does not hold is n/a for that model and is never estimated. See the methodology and each model page for sources.
Frequently asked questions
- Is Gradium TTS faster than Cartesia Sonic 3?
- Speed cannot be compared: Coval does not measure Cartesia Sonic 3, so it has no P95 here.
- How do Gradium TTS and Cartesia Sonic 3 compare on voice quality?
- On Artificial Analysis listener Elo, Gradium TTS is ahead (1,174 for Gradium TTS, 1,054 for Cartesia Sonic 3).
- Which is cheaper, Gradium TTS or Cartesia Sonic 3?
- List price per million characters: $36 to $57.80 for Gradium TTS, $49 to $50 for Cartesia Sonic 3.