Data read October 27, 2026
Gradium TTS vs Inworld Realtime TTS-2 Flash: TTS API comparison
On P95 latency Gradium TTS (104.3 ms) and Inworld Realtime TTS-2 Flash (100.9 ms) are within 10 ms of each other, which the method counts as a tie.
On Artificial Analysis listener Elo, Inworld Realtime TTS-2 Flash is ahead (1,174 for Gradium TTS, 1,218 for Inworld Realtime TTS-2 Flash). List price per million characters: $36 to $57.80 for Gradium TTS, $10.40 to $15 for Inworld Realtime TTS-2 Flash.
Gradium TTS is ranked 1 of 23; Inworld Realtime TTS-2 Flash is ranked 1 of 23. Every comparison on this site uses Gradium TTS as its fixed reference, and no page says either model is better overall.
| Measure | Gradium TTS | Inworld Realtime TTS-2 Flash | Ahead |
|---|---|---|---|
| Rank in the multilingual speed ranking | 1 | 1 | n/a |
| Speed tier | Headroom | Headroom | n/a |
| Median time to first audio (ms), lower is faster | 53.7 | 58.1 | Tie |
| P95 time to first audio (ms), lower is faster | 104.3 | 100.9 | Tie |
| Listener Elo (Artificial Analysis) | 1,174 | 1,218 | Inworld Realtime TTS-2 Flash |
| Customer-service Elo (Artificial Analysis) | 1,241 | 1,244 | Tie |
| Naturalness (Speko) | 1,592 | 1,501 | Gradium TTS |
| Naturalness estimate (Cekura, 1 to 5) | 4.51 | 4.46 | Gradium TTS |
| Reading accuracy (Cekura) | 79.5% | 93.2% | Inworld Realtime TTS-2 Flash |
| Hard passages judged correct (Artificial Analysis) | n/a | 77.8% | n/a |
| Lowest list price per 1M characters (lower is cheaper) | $36 to $57.80 | $10.40 to $15 | Inworld Realtime TTS-2 Flash |
| Languages tested (Artificial Analysis, Speko) | 4 | 9 | Inworld Realtime TTS-2 Flash |
| Access | Proprietary | Proprietary | n/a |
| Streaming status | Measured | Measured | 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 Inworld Realtime TTS-2 Flash?
- On P95 latency Gradium TTS (104.3 ms) and Inworld Realtime TTS-2 Flash (100.9 ms) are within 10 ms of each other, which the method counts as a tie.
- How do Gradium TTS and Inworld Realtime TTS-2 Flash compare on voice quality?
- On Artificial Analysis listener Elo, Inworld Realtime TTS-2 Flash is ahead (1,174 for Gradium TTS, 1,218 for Inworld Realtime TTS-2 Flash).
- Which is cheaper, Gradium TTS or Inworld Realtime TTS-2 Flash?
- List price per million characters: $36 to $57.80 for Gradium TTS, $10.40 to $15 for Inworld Realtime TTS-2 Flash.