← Text-to-Speech

Deepgram

flux

Measured 2026-07-03

Naturalness

~1550

Win % · 95% CI

Drift

25

variance analyzer, 20 repeats, run 2026-09-02T10-00-22-058Z, measured 2026-09-02. Single draw; not comparable with other rows in this column.

Synth p50

106ms

106–148 p50–p90

Mean of two 2026-08-12 sweeps (104/108 p50), n=30 each, concurrency 1, one keep-alive connection, 0 rejected. Anchors in the same sweeps came in 11–26% off their published cells, so the column needs a full re-baseline before these are read against each other.

Robustness

0.41

Fined:

• minor · currency (international, ×0.4) — kept the value but never said “forty five”; a prompt fixes this (7 of 16 transcripts)

→ we sent “Balance: -€45,90 outstanding.”

→ it said “Balance: negative four thousand five hundred and ninety euros outstanding.”

• minor · dates — kept the value but never said “july”; a prompt fixes this (7 of 16 transcripts)

→ we sent “Your appointment is on 07/15/2026.”

→ it said “Your appointment is on zero seven fifteen, twenty twenty six.”

• minor · dates — kept the value but never said “january”; a prompt fixes this (7 of 16 transcripts)

→ we sent “Renewal falls on 1/1/2027.”

→ it said “Renewal falls on one one twenty twenty seven.”

• minor · dates — kept the value but never said “november”; a prompt fixes this (7 of 16 transcripts)

→ we sent “The policy started 11/30/2024.”

→ it said “The policy started eleven thirty, twenty twenty four.”

• minor · dates — kept the value but never said “october”; a prompt fixes this (7 of 16 transcripts)

→ we sent “The deadline moved to 10/02.”

→ it said “The deadline moved to ten zero two.”

• minor · dates — kept the value but never said “march”; a prompt fixes this (3 of 5 transcripts)

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

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

• minor · dates — kept the value but never said “february”; a prompt fixes this (7 of 16 transcripts)

→ we sent “Renewal is 02/29/2024.”

→ it said “Renewal is zero two twenty nine twenty twenty four.”

• minor · dates (international, ×0.4) — kept the value but never said “march”; a prompt fixes this (7 of 16 transcripts)

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

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

• minor · dates (international, ×0.4) — kept the value but never said “june”; a prompt fixes this (7 of 16 transcripts)

→ we sent “The lease ends 2025/06/30.”

→ it said “The lease ends twenty twenty five zero six thirty.”

• fatal · large numbers — never said “zero zero” (5 of 5 transcripts)

→ we sent “Only 007 seats remain.”

→ it said “Only seven seats remain.”

• minor · math operators — kept the value but never said “minus”; a prompt fixes this (3 of 5 transcripts)

→ we sent “That leaves 10-4=6 remaining.”

→ it said “That leaves ten, four equals six remaining.”

• minor · math operators — kept the value but never said “three quarters”; a prompt fixes this (5 of 5 transcripts)

→ we sent “Give me 3/4 of the batch.”

→ it said “Give me three-four of the batch.”

• fatal · math operators — never said “times” (3 of 5 transcripts)

→ we sent “Check it: 7×8=56, not 54.”

→ it said “Check it. 7 psi equals 56, not 54.”

• fatal · math operators — never said “divided” (5 of 5 transcripts)

→ we sent “That is 100÷4=25 per person.”

→ it said “That is 104 equals 25 per person.”

Cost / 1M chars

$45.0

Deepgram published list, Pay As You Go: $0.0450 per 1,000 characters = $45/1M. Same unit that puts Aura-2 at $0.030/1k = the $30 cell above, so the two are directly comparable — Flux TTS costs 50% more than Aura-2. Growth tier is $0.0405/1k ($40.5/1M). Free to build against through 2026-09-12 (45 concurrent streams globally, 5 EU/AU); billing starts 09-13.

Share this result

Embed the live badge

Speko tts rank
Markdown
[![Speko tts rank](https://benchmarks.speko.ai/badge/tts/deepgram-flux.svg)](https://benchmarks.speko.ai/tts/deepgram-flux)
HTML
<a href="https://benchmarks.speko.ai/tts/deepgram-flux"><img src="https://benchmarks.speko.ai/badge/tts/deepgram-flux.svg" alt="Speko tts rank"></a>
URL
https://benchmarks.speko.ai/tts/deepgram-flux