Gradium TTS Gradium · text-to-speech (TTS) API

Speed

On Coval's 30-day window ending October 22, 2026 (3,376 runs from US East), Gradium TTS starts speaking after 54.5 ms on a typical turn (median) and 100.7 ms on a slow turn (P95, the slowest one in twenty). That P95 is 4th lowest of the 32 models Coval measures, which puts it in the Headroom tier: headroom to spend elsewhere in the turn. On the median it is a tie (gap under 10 ms) with Alibaba Qwen3 TTS Fast and Inworld Realtime TTS-2 Flash. Speko's board plots it at 55 ms time to first audio from US East; its model page reports a 105 ms sweep.

Voice quality

Speko rates its naturalness at 1,592 Elo from blind A/B votes on phone-agent lines (6th highest of the 43 models Speko rates). In the Artificial Analysis Speech Arena it holds 1,176 ±13 Elo (95% interval), 23rd highest of the 98 models Artificial Analysis rates; scores whose intervals overlap are a tie. In its Customer Service category, Artificial Analysis places it 16th, at 1,242 Elo.

Numbers and dates

Speko's pronunciation test on numbers, dates and currency scores it 0.27 on a 0-to-1 scale (18th highest of the 30 models Speko scores). This is the accuracy measure used here; Coval's word error rate separates models too little to compare them.

Price

Artificial Analysis lists $47.8. Speko lists about $57.8. Gradium's own plans work out to $57.8 (XS), $47.8 (S), $37.8 (M), $35.9 (L) per 1M characters (gradium.ai/pricing). List prices, as each source prints them: a range of $35.9 to $57.8.

Languages tested

Tested in Spanish, German, French and Portuguese by Artificial Analysis or Speko. A language missing here was not tested, which does not mean it is unsupported.