Voice AI BenchmarksBy

SPACEXAITEXT-TO-SPEECH7,674 SAMPLES / 30 DAYSLAST RUN OCT 14, 2026, 17:30 UTC

official resource

Grok TTS text-to-speech benchmarks

Grok TTS, hosted by SpaceXAI, measures mean 363 ms time to first audio (24th of 32) and 1.6% word error rate (8th of 32) among TTS systems. Results cover the last 30 days. Coval benchmarks hosted endpoints daily using a consistent evaluation methodology. Last measured .

Grok TTS is SpaceXAI's managed speech synthesis model.

Time to First Audio#24 / 32
363ms
TTFA Network Roundtrip#26 / 32
309ms
TTFA Leading Silence#13 / 32
54ms
Word Error Rate#8 / 32
1.6%

Overview

The tested SpaceXAI service supports multilingual output, voice cloning and emotion controls.

Grok TTS is tested every day on a fixed set of text prompts, measuring how quickly audible speech starts and how intelligible the result is.

Technical specifications

Made by
SpaceXAI
Hosted by
SpaceXAI
Source
Official API
Licensing
Proprietary
Deployment
Cloud
Region
US
Features
Emotion control, Multilingual, Voice cloning

How Grok TTS ranks

Full TTS dashboard
Time to First Audio — every measured TTS modelMilliseconds · lower is better · 30-day averageEvery TTS model ranked on Time to First Audio, with Grok TTS highlighted.
  1. #1vui59 ms
  2. #2Default63 ms
  3. #3Qwen3 TTS Fast68 ms
  4. #4TTS Flash 291 ms
  5. #5Qwen3 TTS 1.7b107 ms
  6. #6Simba 3.0111 ms
  7. #7Palabra TTS120 ms
  8. #8Simba 3.2126 ms
  9. #9drama3-preview167 ms
  10. #10TTS 2191 ms
  11. #11Flash v2.5192 ms
  12. #12Eleven v4 Turbo201 ms
  13. #13Flux TTS205 ms
  14. #14TTS RT v1255 ms
  15. #15TTS Rt v2256 ms
  16. #16Mist v3287 ms
  17. #17Phantom Z 3.4 conversational290 ms
  18. #18Sonic 3.5293 ms
  19. #19Aura 2297 ms
  20. #20Sonic 3.6299 ms
  21. #21Falcon 2299 ms
  22. #22Coda332 ms
  23. #23S2.1 Pro341 ms
  24. #24Grok TTS363 ms
Show all 32 models
  1. #25S1390 ms
  2. #26Lightning v3.1 Pro392 ms
  3. #27Daytona TTS486 ms
  4. #28Aura 2 En569 ms
  5. #29Chirp 3 HD598 ms
  6. #30Qwen3 TTS Flash Realtime718 ms
  7. #31S2.1 Pro Free849 ms
  8. #32GPT-4o mini TTS2585 ms
median of all models · 288 ms
TTS models over the last 30 days, ranked on Time to First Audio.
#ModelHostTTFAWERSamples
1vuiFluxions59 ms1,752
2Gradium TTS Beta 202609Gradium63 ms1,924
3Qwen3 TTS FastNari Labs68 ms1,924
4TTS Flash 2Inworld AI91 ms1,728
5Qwen3 TTS 1.7bBaseten107 ms1,248
6Simba 3.0SpeechifyAI111 ms1,923
7Palabra TTS v1Palabra120 ms1,584
8Simba 3.2SpeechifyAI126 ms1,920
9Drama 3 Preview Us EastFish Audio167 ms170
10TTS 2Inworld AI191 ms1,728
11Flash v2.5ElevenLabs192 ms1,914
12Eleven v4 TurboElevenLabs201 ms1,234
13Flux TTSDeepgram205 ms1,787
14TTS RT v1Soniox255 ms1,626
15TTS Rt v2Soniox256 ms1,623
16Mist v3Rime287 ms602
17Phantom Z 3.4 conversationalDeepdub290 ms1,659
18Sonic 3.5Cartesia293 ms1,924
19Aura 2Deepgram297 ms1,856
20Sonic 3.6Cartesia299 ms1,924
21Falcon 2Murf299 ms1,923
22CodaRime332 ms602
23S2.1 ProFish Audio341 ms1,924
24Grok TTSSpaceXAI363 ms1,919
25S1Fish Audio390 ms1,923
26Lightning v3.1 ProSmallest392 ms1,924
27Daytona TTSGuava486 ms1,152
28Aura 2 EnCloudflare569 ms1,923
29Chirp 3 HDGoogle598 ms1,924
30Qwen3 TTS Flash RealtimeAlibaba718 ms1,923
31S2.1 Pro FreeFish Audio849 ms1,917
32GPT-4o mini TTSOpenAI2585 ms1,849
Under-sampled models are excluded; tied models share a place. Dotted WER values split into substitutions, deletions and insertions on hover or tap.

Highest relative placement: 8th of 32 on Word Error Rate.

Latency vs accuracy

TTFA vs WEREach point is one measured model · Grok TTS highlighted · 30-day averagesTime to First Audio against Word Error Rate for every measured TTS model, with Grok TTS highlighted.
vui — 59 ms, 2.1%Default — 63 ms, 1.9%Qwen3 TTS Fast — 68 ms, 1.8%TTS Flash 2 — 91 ms, 1.7%Qwen3 TTS 1.7b — 107 ms, 1.8%Simba 3.0 — 111 ms, 1.5%Palabra TTS — 120 ms, 2.6%Simba 3.2 — 126 ms, 1.9%drama3-preview — 167 ms, 2.0%TTS 2 — 191 ms, 1.6%Flash v2.5 — 192 ms, 1.8%Eleven v4 Turbo — 201 ms, 1.7%Flux TTS — 205 ms, 1.7%TTS RT v1 — 255 ms, 2.4%TTS Rt v2 — 256 ms, 2.4%Mist v3 — 287 ms, 2.1%Phantom Z 3.4 conversational — 290 ms, 1.8%Sonic 3.5 — 293 ms, 1.5%Aura 2 — 297 ms, 1.8%Sonic 3.6 — 299 ms, 1.5%Falcon 2 — 299 ms, 1.7%Coda — 332 ms, 9.5%S2.1 Pro — 341 ms, 1.5%S1 — 390 ms, 1.8%Lightning v3.1 Pro — 392 ms, 1.5%Daytona TTS — 486 ms, 1.6%Aura 2 En — 569 ms, 2.1%Chirp 3 HD — 598 ms, 1.5%Qwen3 TTS Flash Realtime — 718 ms, 3.0%S2.1 Pro Free — 849 ms, 1.5%GPT-4o mini TTS — 2585 ms, 1.8%Grok TTS — 363 ms, 1.6%

Where the errors come from

WER compositionGrok TTS's Word Error Rate split by error type · 30-day averageGrok TTS's WER split into substitutions, deletions and insertions.
  • Grok TTS1.6%
SubstitutionsDeletionsInsertions

Averages and tail latency

Averages hide slow outliers — these are the distributions behind each figure.

Grok TTS latency distributionMilliseconds · shared axis across metrics · last 30 daysGrok TTS's latency percentiles per metric: p25–p75 band, p50 tick, whisker to max.
  • Time to First Audiop50 349 ms · Max 5417 ms
  • TTFA Network Roundtripp50 299 ms · Max 5408 ms
  • TTFA Leading Silencep50 50 ms · Max 201 ms
band p25–p75 · tick p50 · whisker to max with p90 and p95 stops
Average and percentile values per metric, with the number of samples behind each row.
MetricAveragep25p50p75p90p95MaxSamples
Time to First Audio363 ms310 ms349 ms391 ms440 ms478 ms5417 ms1,919
TTFA Network Roundtrip309 ms259 ms299 ms332 ms374 ms413 ms5408 ms1,919
TTFA Leading Silence54 ms38 ms50 ms65 ms93 ms102 ms201 ms1,919
Word Error Rate1.6%0.0%0.0%2.1%6.9%12.2%43.8%1,917

Last 30 days

Daily medians from the same measurement runs · gaps are days without qualifying runs.

Time to First Audio — daily p50Line p50 · band p25–p75 · UTC daysGrok TTS's daily median Time to First Audio over the last 30 days.
Grok TTS · Sep 23: 439 msGrok TTS · Sep 24: 381 msGrok TTS · Sep 25: 390 msGrok TTS · Sep 26: 357 msGrok TTS · Sep 27: 359 msGrok TTS · Sep 28: 477 msGrok TTS · Sep 29: 375 msGrok TTS · Sep 30: 325 msGrok TTS · Oct 1: 397 msGrok TTS · Oct 2: 369 msGrok TTS · Oct 3: 321 msGrok TTS · Oct 4: 354 msGrok TTS · Oct 5: 318 msGrok TTS · Oct 6: 362 msGrok TTS · Oct 7: 449 msGrok TTS · Oct 8: 406 msGrok TTS · Oct 9: 286 msGrok TTS · Oct 10: 330 msGrok TTS · Oct 11: 311 msGrok TTS · Oct 12: 373 msGrok TTS · Oct 13: 331 msGrok TTS · Oct 14: 329 ms
Word Error Rate — daily averageDaily average · UTC daysGrok TTS's daily Word Error Rate over the last 30 days.
Grok TTS · Sep 23: 4.7%Grok TTS · Sep 24: 3.6%Grok TTS · Sep 25: 4.7%Grok TTS · Sep 26: 3.1%Grok TTS · Sep 27: 5.3%Grok TTS · Sep 28: 7.2%Grok TTS · Sep 29: 3.3%Grok TTS · Sep 30: 2.1%Grok TTS · Oct 1: 4.9%Grok TTS · Oct 2: 4.1%Grok TTS · Oct 3: 4.6%Grok TTS · Oct 4: 6.4%Grok TTS · Oct 5: 3.1%Grok TTS · Oct 6: 4.4%Grok TTS · Oct 7: 5.6%Grok TTS · Oct 8: 5.4%Grok TTS · Oct 9: 3.1%Grok TTS · Oct 10: 1.3%Grok TTS · Oct 11: 3.2%Grok TTS · Oct 12: 4.6%Grok TTS · Oct 13: 4.2%Grok TTS · Oct 14: 6.4%

How fast is Grok TTS?

On SpaceXAI, Grok TTS measures mean 363 ms time to first audio (24th of 32). Last measured 2026-10-14.

How accurate is Grok TTS?

On SpaceXAI, Grok TTS measures 1.6% word error rate (8th of 32). Last measured 2026-10-14.

Who hosts Grok TTS?

Grok TTS is created by SpaceXAI and served by SpaceXAI. Coval measures each hosted endpoint separately.

Limits of this comparison

Coval benchmarks the official endpoint on common prompts to compare audible response timing and output intelligibility.

  • The benchmark does not evaluate cloning similarity, expressive quality or every available SpaceXAI voice.

Official sources

Results are re-measured daily using fixed datasets and reported over a rolling 30-day window. Same datasets, prompts and metric definitions for every model, measured by Coval’s open-source runner. Full methodology on the overview.

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