Data read October 27, 2026
Gradium TTS vs StepFun StepAudio 2.5 TTS (Aug 2026): TTS API comparison
Speed cannot be compared: Coval does not measure StepFun StepAudio 2.5 TTS (Aug 2026), so it has no P95 here.
On Artificial Analysis listener Elo, StepFun StepAudio 2.5 TTS (Aug 2026) is ahead (1,174 for Gradium TTS, 1,212 for StepFun StepAudio 2.5 TTS (Aug 2026)). List price per million characters: $36 to $57.80 for Gradium TTS, $85 for StepFun StepAudio 2.5 TTS (Aug 2026).
Gradium TTS is ranked 1 of 23; StepFun StepAudio 2.5 TTS (Aug 2026) 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 | StepFun StepAudio 2.5 TTS (Aug 2026) | 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 | 1,212 | StepFun StepAudio 2.5 TTS (Aug 2026) |
| Customer-service Elo (Artificial Analysis) | 1,241 | 1,243 | Tie |
| 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 | 73.0% | n/a |
| Lowest list price per 1M characters (lower is cheaper) | $36 to $57.80 | $85 | Gradium TTS |
| 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 StepFun StepAudio 2.5 TTS (Aug 2026)?
- Speed cannot be compared: Coval does not measure StepFun StepAudio 2.5 TTS (Aug 2026), so it has no P95 here.
- How do Gradium TTS and StepFun StepAudio 2.5 TTS (Aug 2026) compare on voice quality?
- On Artificial Analysis listener Elo, StepFun StepAudio 2.5 TTS (Aug 2026) is ahead (1,174 for Gradium TTS, 1,212 for StepFun StepAudio 2.5 TTS (Aug 2026)).
- Which is cheaper, Gradium TTS or StepFun StepAudio 2.5 TTS (Aug 2026)?
- List price per million characters: $36 to $57.80 for Gradium TTS, $85 for StepFun StepAudio 2.5 TTS (Aug 2026).