← Text-to-Speech

xAI Grok

grok-tts

Measured 2026-07-03

Naturalness

1495

Win % · 95% CI

48%

42–55%

Drift

15

Synth p50

272ms

272–325 p50–p90

Robustness

0.43

Fined:

• fatal · currency — dropped the minus sign (7 of 7 transcripts)

→ we sent “Your balance is -$1,204.50 as of today.”

→ it said “Your balance is $1,204.50 as of today.”

• minor · dates — said “slash” out loud; a prompt fixes this (3 of 7 transcripts)

→ we sent “Your slot is 03/09 this year.”

→ it said “Your slot is zero three slash zero nine this year.”

• minor · dates (international, ×0.4) — kept the value but never said “march”; a prompt fixes this (4 of 7 transcripts)

→ we sent “The order shipped on 2026-03-09.”

→ it said “The order shipped on twenty twenty six zero three zero nine.”

• fatal · decimals — dropped the minus sign (1 of 7 transcripts)

→ we sent “Growth slowed to -0.5% this month.”

→ it said “Growth slowed to 0.5% this month.”

Cost / 1M chars

$15.0

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