Data read October 27, 2026
Gradium TTS vs OpenAI GPT-4o mini TTS: TTS API comparison
Speed cannot be compared: Coval does not measure OpenAI GPT-4o mini TTS, so it has no P95 here.
Listener Elo is not available for both models, so voice preference is not compared. List price per million characters: $36 to $57.80 for Gradium TTS, $20 for OpenAI GPT-4o mini TTS.
Gradium TTS is ranked 1 of 23; OpenAI GPT-4o mini TTS 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 | OpenAI GPT-4o mini TTS | 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 | n/a | n/a |
| Customer-service Elo (Artificial Analysis) | 1,241 | n/a | n/a |
| Naturalness (Speko) | 1,592 | 1,424 | 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 | $20 | OpenAI GPT-4o mini TTS |
| Languages tested (Artificial Analysis, Speko) | 4 | 9 | OpenAI GPT-4o mini TTS |
| Access | Proprietary | n/a | 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 OpenAI GPT-4o mini TTS?
- Speed cannot be compared: Coval does not measure OpenAI GPT-4o mini TTS, so it has no P95 here.
- How do Gradium TTS and OpenAI GPT-4o mini TTS compare on voice quality?
- Listener Elo is not available for both models, so voice preference is not compared.
- Which is cheaper, Gradium TTS or OpenAI GPT-4o mini TTS?
- List price per million characters: $36 to $57.80 for Gradium TTS, $20 for OpenAI GPT-4o mini TTS.