TTS API comparison 2026
Gradium TTS Beta vs Fluxions vui Gradium vs Fluxions · text-to-speech for voice agents
Gradium TTS Beta ranks 1st of 112 with 76.8/100; Fluxions vui ranks 15th with 47/100: a gap of 29.8 points on the same public rules, built on Coval, Speko and Artificial Analysis.
Data checked on September 30, 2026 · Coval 30-day window ending October 1, 2026 · updated after each benchmark capture
Side-by-side benchmark
| Measure | Gradium TTS Beta | Fluxions vui |
|---|---|---|
| Overall score | 76.8/100 | 47/100 |
| Rank | 1st of 112 | 15th of 112 |
| Real-time speed /60 | 58.7 | 44.6 |
| Voice quality /20 | 7.8 | 0 |
| Accuracy /15 | 9.8 | 2.4 |
| Price /5 | 0.5 | 0 |
| P50 / median time-to-first-audio Coval, 30-day window | 47.2 ms | 50.2 ms |
| P99 time-to-first-audio (slowest turns) Coval, 30-day window | 108.8 ms | 128.1 ms |
| Latency consistency (standard deviation) Coval, 30-day window | 16.6 ms | 241.6 ms |
| P50 time-to-first-audio, US East Speko | 100 ms | not measured |
| Accuracy: word error rate (WER) Coval, 30-day window | 4.5% | 5.2% |
| Pronunciation robustness (0 to 1) Speko | 0.3 | not measured |
| Speech Arena Elo (blind listener preference) Artificial Analysis | not measured | not measured |
| Naturalness (Elo) Speko | 1579 | not measured |
| Price per 1M characters Artificial Analysis | not measured | not measured |
Choose Gradium TTS Beta if…
- → Ranks 1st of 112 in the overall benchmark, against 15th for Fluxions vui
- → Better P50 / median time-to-first-audio: 47.2 ms vs 50.2 ms (Coval, 30-day window)
- → Better P99 time-to-first-audio (slowest turns): 108.8 ms vs 128.1 ms (Coval, 30-day window)
- → Better latency consistency (standard deviation): 16.6 ms vs 241.6 ms (Coval, 30-day window)
- → Better accuracy: word error rate (WER): 4.5% vs 5.2% (Coval, 30-day window)
Choose Fluxions vui if…
On the published benchmarks, Fluxions vui wins none of the measurements above against Gradium TTS Beta. This says nothing about features the benchmarks do not measure.
Fluxions vui: all measurements →Frequently asked questions
- What is the difference between Gradium TTS Beta and Fluxions vui?
- In the 2026 TTS API benchmark, Gradium TTS Beta ranks 1st of 112 with 76.8/100 and Fluxions vui ranks 15th with 47/100, a gap of 29.8 points on the same rules.
- Which is faster for real-time voice agents, Gradium TTS Beta or Fluxions vui?
- On Coval's 30-day window ending October 1, 2026, the P50 time-to-first-audio is 47.2 ms for Gradium TTS Beta and 50.2 ms for Fluxions vui; the P99 is 108.8 ms and 128.1 ms.
- On which criteria does Fluxions vui beat Gradium TTS Beta?
- On the 4 criteria of the benchmark, Fluxions vui scores higher on none.
- How are these two text-to-speech APIs scored?
- Both are scored by the same public rules: 4 criteria, 100 points (Real-time speed 60, Voice quality 20, Accuracy 15, Price 5), computed from three independent benchmarks: Coval, Speko and Artificial Analysis. A measurement a benchmark does not publish counts zero, and the model page says why.
- Can these numbers be checked?
- Yes. Each model page lists every measurement with its source and date, and links to the benchmark page it comes from. The rules are on the methodology page.