Voice AI BenchmarksBy

XAITEXT-TO-SPEECH51,356 SAMPLES / 30 DAYSLAST RUN AUG 28, 2026, 21:30 UTC

official resource

Grok TTS text-to-speech benchmarks

Grok TTS is xAI's managed speech synthesis model.

Time to First Audio#18 / 30
420ms
TTFA Network Roundtrip#22 / 28
365ms
TTFA Leading Silence#9 / 28
59ms
Word Error Rate#11 / 30
4.7%

Overview

The tested xAI 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
xAI
Hosted by
xAI
Source
Official API
Licensing
Proprietary
Deployment
Cloud
Region
US
Features
Multilingual, Voice cloning, Emotion control

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. #1Palabra TTS v1116 ms
  2. #2vui124 ms
  3. #3TTS Flash 2128 ms
  4. #4TTS 2176 ms
  5. #5Blizzard235 ms
  6. #6Neural236 ms
  7. #7Mist v3256 ms
  8. #8TTS Rt v2262 ms
  9. #9Sonic 3.5274 ms
  10. #10TTS RT v1275 ms
  11. #11Dragon HD Latest310 ms
  12. #12Coda313 ms
  13. #13Aura 2328 ms
  14. #14S2.1 Pro374 ms
  15. #15Default384 ms
  16. #16Speech 2.8 Turbo411 ms
  17. #17Eleven v3 Conversational412 ms
  18. #18Grok TTS420 ms
Show all 30 models
  1. #19S1434 ms
  2. #20Flash v2.5455 ms
  3. #21Speech 2.8 HD460 ms
  4. #22Sonic 3.6466 ms
  5. #23Simba 3.2484 ms
  6. #24Chirp 3 HD512 ms
  7. #25Simba 3.0526 ms
  8. #26Falcon 2549 ms
  9. #27Lightning v3.1 Pro586 ms
  10. #28Qwen3 TTS Flash Realtime645 ms
  11. #29S2.1 Pro Free806 ms
  12. #30GPT-4o mini TTS1075 ms
median of all models · 397 ms
TTS models over the last 30 days, ranked on Time to First Audio.
#ModelHostTTFAWERSamples
1Palabra TTS v1Palabra116 ms5.9%14,396
2vuiFluxions124 ms8,624
3TTS Flash 2Inworld AI128 ms8,719
4TTS 2Inworld AI176 ms4.8%14,529
5BlizzardLmnt235 ms7.4%14,117
6NeuralAzure236 ms4.3%3,350
7Mist v3Rime256 ms6.3%14,524
8TTS Rt v2Soniox262 ms8,849
9Sonic 3.5Cartesia274 ms6.1%14,513
10TTS RT v1Soniox275 ms3.7%14,528
11Dragon HD LatestAzure310 ms5.1%3,350
12CodaRime313 ms5.2%14,523
13Aura 2Deepgram328 ms5.3%14,501
14S2.1 ProFish Audio374 ms10,222
15DefaultGradium384 ms4.6%14,002
16Speech 2.8 TurboMiniMax411 ms4.8%1,997
17Eleven v3 ConversationalElevenLabs412 ms6,750
18Grok TTSxAI420 ms4.7%14,524
19S1Fish Audio434 ms4.9%10,236
20Flash v2.5ElevenLabs455 ms6.7%9,259
21Speech 2.8 HDMiniMax460 ms1,995
22Sonic 3.6Cartesia466 ms560
23Simba 3.2Speechify484 ms4.7%14,525
24Chirp 3 HDGoogle512 ms5.2%14,530
25Simba 3.0Speechify526 ms5.3%14,526
26Falcon 2Murf549 ms10,229
27Lightning v3.1 ProSmallest586 ms4.4%14,515
28Qwen3 TTS Flash RealtimeAlibaba645 ms8.8%14,530
29S2.1 Pro FreeFish Audio806 ms4.7%14,464
30GPT-4o mini TTSOpenAI1075 ms4.8%14,517
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: 11th of 30 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.
Palabra TTS v1 — 116 ms, 5.9%vui — 124 ms, 7.9%TTS Flash 2 — 128 ms, 4.9%TTS 2 — 176 ms, 4.8%Blizzard — 235 ms, 7.4%Neural — 236 ms, 4.3%Mist v3 — 256 ms, 6.3%TTS Rt v2 — 262 ms, 3.9%Sonic 3.5 — 274 ms, 6.1%TTS RT v1 — 275 ms, 3.7%Dragon HD Latest — 310 ms, 5.1%Coda — 313 ms, 5.2%Aura 2 — 328 ms, 5.3%S2.1 Pro — 374 ms, 4.6%Default — 384 ms, 4.6%Speech 2.8 Turbo — 411 ms, 4.8%Eleven v3 Conversational — 412 ms, 4.4%S1 — 434 ms, 4.9%Flash v2.5 — 455 ms, 6.7%Speech 2.8 HD — 460 ms, 4.7%Sonic 3.6 — 466 ms, 5.5%Simba 3.2 — 484 ms, 4.7%Chirp 3 HD — 512 ms, 5.2%Simba 3.0 — 526 ms, 5.3%Falcon 2 — 549 ms, 5.2%Lightning v3.1 Pro — 586 ms, 4.4%Qwen3 TTS Flash Realtime — 645 ms, 8.8%S2.1 Pro Free — 806 ms, 4.7%GPT-4o mini TTS — 1075 ms, 4.8%Grok TTS — 420 ms, 4.7%

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 p99.
  • Time to First Audiop50 398 ms · p99 691 ms
  • TTFA Network Roundtripp50 332 ms · p99 645 ms
  • TTFA Leading Silencep50 52 ms · p99 140 ms
band p25–p75 · tick p50 · whisker to p99 with p90 and p95 stops
Average and percentile values per metric, with the number of samples behind each row.
MetricAveragep25p50p75p90p95p99Samples
Time to First Audio420 ms365 ms398 ms437 ms484 ms528 ms691 ms14,524
TTFA Network Roundtrip365 ms312 ms332 ms375 ms424 ms466 ms645 ms11,154
TTFA Leading Silence59 ms40 ms52 ms76 ms100 ms112 ms140 ms11,154
Word Error Rate4.7%0.0%0.0%7.7%18.8%20.0%31.3%14,524

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 · Jul 31: 366 msGrok TTS · Aug 1: 415 msGrok TTS · Aug 2: 397 msGrok TTS · Aug 3: 397 msGrok TTS · Aug 4: 399 msGrok TTS · Aug 5: 420 msGrok TTS · Aug 6: 381 msGrok TTS · Aug 7: 425 msGrok TTS · Aug 8: 408 msGrok TTS · Aug 9: 398 msGrok TTS · Aug 10: 402 msGrok TTS · Aug 11: 404 msGrok TTS · Aug 12: 450 msGrok TTS · Aug 13: 386 msGrok TTS · Aug 14: 437 msGrok TTS · Aug 15: 406 msGrok TTS · Aug 16: 392 msGrok TTS · Aug 17: 491 msGrok TTS · Aug 18: 484 msGrok TTS · Aug 19: 384 msGrok TTS · Aug 20: 358 msGrok TTS · Aug 21: 384 msGrok TTS · Aug 22: 372 msGrok TTS · Aug 23: 381 msGrok TTS · Aug 24: 378 msGrok TTS · Aug 25: 387 msGrok TTS · Aug 26: 357 msGrok TTS · Aug 27: 378 msGrok TTS · Aug 28: 412 ms
Word Error Rate — daily averageDaily average · UTC daysGrok TTS's daily Word Error Rate over the last 30 days.
Grok TTS · Jul 31: 3.7%Grok TTS · Aug 1: 4.6%Grok TTS · Aug 2: 5.4%Grok TTS · Aug 3: 4.4%Grok TTS · Aug 4: 4.5%Grok TTS · Aug 5: 4.2%Grok TTS · Aug 6: 4.2%Grok TTS · Aug 7: 4.9%Grok TTS · Aug 8: 5.0%Grok TTS · Aug 9: 4.6%Grok TTS · Aug 10: 4.5%Grok TTS · Aug 11: 5.6%Grok TTS · Aug 12: 5.7%Grok TTS · Aug 13: 4.0%Grok TTS · Aug 14: 5.4%Grok TTS · Aug 15: 5.0%Grok TTS · Aug 16: 5.0%Grok TTS · Aug 17: 5.6%Grok TTS · Aug 18: 5.1%Grok TTS · Aug 19: 5.2%Grok TTS · Aug 20: 5.7%Grok TTS · Aug 21: 5.1%Grok TTS · Aug 22: 4.7%Grok TTS · Aug 23: 5.1%Grok TTS · Aug 24: 4.7%Grok TTS · Aug 25: 5.2%Grok TTS · Aug 26: 5.4%Grok TTS · Aug 27: 5.0%Grok TTS · Aug 28: 4.9%

Time to First Audio by dataset

Grok TTS by test conditionMilliseconds · lower is better · best condition firstGrok TTS's Time to First Audio on each benchmark dataset.
  1. Text prompts420 ms
Time to First Audio per dataset, with the number of samples behind each figure.
DatasetTTFASamples
Text prompts420 ms14,524

Strongest condition: Text prompts at 420 ms · weakest: Text prompts at 420 ms.

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 xAI 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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