Data read October 27, 2026
Gradium TTS vs async Flash v1.0: TTS API comparison
Speed cannot be compared: Coval does not measure async Flash v1.0, so it has no P95 here.
On Artificial Analysis listener Elo, Gradium TTS is ahead (1,174 for Gradium TTS, 1,049 for async Flash v1.0). List price per million characters: $36 to $57.80 for Gradium TTS, $10.10 for async Flash v1.0.
Gradium TTS is ranked 1 of 23; async Flash v1.0 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 | async Flash v1.0 | 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 | 1,049 | Gradium TTS |
| Customer-service Elo (Artificial Analysis) | 1,241 | 1,059 | Gradium TTS |
| Naturalness (Speko) | 1,592 | n/a | n/a |
| 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 | $10.10 | async Flash v1.0 |
| Languages tested (Artificial Analysis, Speko) | 4 | 0 | Gradium TTS |
| 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 async Flash v1.0?
- Speed cannot be compared: Coval does not measure async Flash v1.0, so it has no P95 here.
- How do Gradium TTS and async Flash v1.0 compare on voice quality?
- On Artificial Analysis listener Elo, Gradium TTS is ahead (1,174 for Gradium TTS, 1,049 for async Flash v1.0).
- Which is cheaper, Gradium TTS or async Flash v1.0?
- List price per million characters: $36 to $57.80 for Gradium TTS, $10.10 for async Flash v1.0.