Smallest.ai Lightning V3.1 Pro (Jul 2026) Smallest.ai · text-to-speech (TTS) API

Speed

On Coval's 30-day window ending October 22, 2026 (3,369 runs from US East), Smallest.ai Lightning V3.1 Pro (Jul 2026) starts speaking after 356.1 ms on a typical turn (median) and 691 ms on a slow turn (P95, the slowest one in twenty). That P95 is 27th lowest of the 32 models Coval measures, which puts it in the Visible delay tier: the voice becomes a visible part of the delay. On the median it is a tie (gap under 10 ms) with SpaceXAI Grok TTS. Speko's board plots it at 839 ms time to first audio from US East.

Voice quality

Speko rates its naturalness at 1,447 Elo from blind A/B votes on phone-agent lines (32nd highest of the 43 models Speko rates). In the Artificial Analysis Speech Arena it holds 1,169 ±12 Elo (95% interval), 25th highest of the 98 models Artificial Analysis rates; scores whose intervals overlap are a tie. In its Customer Service category, Artificial Analysis places it 26th, at 1,187 Elo.

Numbers and dates

Speko has not scored its pronunciation of numbers and dates.

Price

Coval lists $19.5 per 1M characters (since Sep 4, 2026). Artificial Analysis lists $19.5. Speko lists about $19.5. List prices, as each source prints them.