Voice AI BenchmarksBy

XAISPEECH-TO-TEXT117,411 SAMPLES / 30 DAYSLAST RUN AUG 28, 2026, 21:30 UTC

official resource

Grok STT speech-to-text benchmarks

Grok STT is xAI's managed streaming speech-to-text offering.

Time to Final Segment#12 / 24
199ms
Word Error Rate#6 / 28
4.8%

Overview

The tested endpoint supports multilingual transcription, diarization and keyterm biasing.

Grok STT is tested every day on fixed public audio — clean, accented, noisy, reverberant, far-field, clipped and phone-codec speech — for transcription accuracy and streaming latency.

Technical specifications

Made by
xAI
Hosted by
xAI
Source
Official API
Licensing
Proprietary
Deployment
Cloud
Region
US
Features
Multilingual, VAD, Diarization, Keyterm biasing

How Grok STT ranks

Full STT dashboard
Time to Final Segment — every measured STT modelMilliseconds · lower is better · 30-day averageEvery STT model ranked on Time to Final Segment, with Grok STT highlighted.
  1. #1STT RT v564 ms
  2. #2Parakeet TDT 0.6B v370 ms
  3. #3STT 183 ms
  4. #4Nova 399 ms
  5. #5Nova 2101 ms
  6. #6Ink 2108 ms
  7. #7Scribe v2 Realtime120 ms
  8. #8Universal 3.5 Pro146 ms
  9. #9Defaultvia Azure155 ms
  10. #10Whisper Large v3180 ms
  11. #11Velma 2 STT Streaming191 ms
  12. #12Grok STT199 ms
Show all 24 models
  1. #13Pulse205 ms
  2. #14Defaultvia Speechmatics223 ms
  3. #15Defaultvia Gradium249 ms
  4. #16resonant-1288 ms
  5. #17Enhanced341 ms
  6. #18Voxtral Mini Transcribe Realtime 2602356 ms
  7. #19GPT Realtime Whisper559 ms
  8. #20GPT-4o mini Transcribe623 ms
  9. #21Solaria 1680 ms
  10. #22GPT-4o Transcribe742 ms
  11. #23Chirp 2811 ms
  12. #24Chirp 3813 ms
median of all models · 202 ms
STT models over the last 30 days, ranked on Time to Final Segment.
#ModelHostTTFSWERTTFTSamples
1STT RT v5Soniox64 ms1533 ms29,322
2Parakeet TDT 0.6B v3Together AI70 ms1210 ms29,161
3STT 1Inworld AI83 ms1468 ms29,280
4Nova 3Deepgram99 ms1434 ms29,290
5Nova 2Deepgram101 ms1436 ms29,145
6Ink 2Cartesia108 ms1812 ms29,288
7Scribe v2 RealtimeElevenLabs120 ms2157 ms29,313
8Universal 3.5 ProAssemblyAI146 ms1030 ms29,280
9DefaultAzure155 ms1792 ms6,682
10Whisper Large v3Together AI180 ms1241 ms29,171
11Velma 2 STT StreamingModulate191 ms1576 ms17,895
12Grok STTxAI199 ms—29,322
13PulseSmallest205 ms2072 ms29,313
14DefaultSpeechmatics223 ms1473 ms29,323
15DefaultGradium249 ms1979 ms28,235
16resonant-1Reson8288 ms—17,066
17EnhancedSpeechmatics341 ms1536 ms29,322
18Voxtral Mini Transcribe Realtime 2602Mistral356 ms1828 ms29,175
19GPT Realtime WhisperOpenAI559 ms1823 ms29,286
20GPT-4o mini TranscribeOpenAI623 ms—29,318
21Solaria 1Gladia680 ms1703 ms26,356
22GPT-4o TranscribeOpenAI742 ms—29,318
23Chirp 2Google811 ms6000 ms29,237
24Chirp 3Google813 ms5999 ms29,319
—FluxDeepgram—1089 ms29,354
—Flux MultilingualDeepgram—1175 ms29,344
—Nemotron 3.5 ASR StreamingTogether AI—1540 ms29,193
—Universal StreamingAssemblyAI—1510 ms29,297
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: 6th of 28 on Word Error Rate.

Latency vs accuracy

TTFS vs WEREach point is one measured model · Grok STT highlighted · 30-day averagesTime to Final Segment against Word Error Rate for every measured STT model, with Grok STT highlighted.
STT RT v5 — 64 ms, 5.8%Parakeet TDT 0.6B v3 — 70 ms, 11.0%STT 1 — 83 ms, 4.8%Nova 3 — 99 ms, 6.3%Nova 2 — 101 ms, 7.9%Ink 2 — 108 ms, 4.9%Scribe v2 Realtime — 120 ms, 5.5%Universal 3.5 Pro — 146 ms, 3.2%Default via Azure — 155 ms, 5.3%Whisper Large v3 — 180 ms, 8.2%Velma 2 STT Streaming — 191 ms, 6.4%Pulse — 205 ms, 5.3%Default via Speechmatics — 223 ms, 5.5%Default via Gradium — 249 ms, 10.0%resonant-1 — 288 ms, 3.4%Enhanced — 341 ms, 4.3%Voxtral Mini Transcribe Realtime 2602 — 356 ms, 6.2%GPT Realtime Whisper — 559 ms, 5.2%GPT-4o mini Transcribe — 623 ms, 5.1%Solaria 1 — 680 ms, 7.1%GPT-4o Transcribe — 742 ms, 4.7%Chirp 2 — 811 ms, 5.0%Chirp 3 — 813 ms, 4.1%Grok STT — 199 ms, 4.8%

Where the errors come from

WER compositionGrok STT's Word Error Rate split by error type · 30-day averageGrok STT's WER split into substitutions, deletions and insertions.
  • Grok STT4.8%
SubstitutionsDeletionsInsertions

Averages and tail latency

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

Grok STT latency distributionMilliseconds · shared axis across metrics · last 30 daysGrok STT's latency percentiles per metric: p25–p75 band, p50 tick, whisker to p99.
  • Time to Final Segmentp50 193 ms · p99 336 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 Final Segment199 ms164 ms193 ms217 ms240 ms258 ms336 ms29,322
Word Error Rate4.8%0.0%0.0%5.6%12.0%19.2%62.5%29,363

Last 30 days

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

Time to Final Segment — daily p50Line p50 · band p25–p75 · UTC daysGrok STT's daily median Time to Final Segment over the last 30 days.
Grok STT · Jul 30: 212 msGrok STT · Jul 31: 173 msGrok STT · Aug 1: 205 msGrok STT · Aug 2: 186 msGrok STT · Aug 3: 180 msGrok STT · Aug 4: 201 msGrok STT · Aug 5: 196 msGrok STT · Aug 6: 192 msGrok STT · Aug 7: 180 msGrok STT · Aug 8: 204 msGrok STT · Aug 9: 197 msGrok STT · Aug 10: 183 msGrok STT · Aug 11: 193 msGrok STT · Aug 12: 192 msGrok STT · Aug 13: 179 msGrok STT · Aug 14: 194 msGrok STT · Aug 15: 188 msGrok STT · Aug 16: 188 msGrok STT · Aug 17: 197 msGrok STT · Aug 18: 198 msGrok STT · Aug 19: 191 msGrok STT · Aug 20: 209 msGrok STT · Aug 21: 177 msGrok STT · Aug 22: 205 msGrok STT · Aug 23: 166 msGrok STT · Aug 24: 192 msGrok STT · Aug 25: 216 msGrok STT · Aug 26: 192 msGrok STT · Aug 27: 192 msGrok STT · Aug 28: 191 ms
Word Error Rate — daily averageDaily average · UTC daysGrok STT's daily Word Error Rate over the last 30 days.
Grok STT · Jul 30: 3.4%Grok STT · Jul 31: 6.2%Grok STT · Aug 1: 10.2%Grok STT · Aug 2: 13.5%Grok STT · Aug 3: 5.4%Grok STT · Aug 4: 5.7%Grok STT · Aug 5: 7.3%Grok STT · Aug 6: 5.0%Grok STT · Aug 7: 7.6%Grok STT · Aug 8: 4.5%Grok STT · Aug 9: 5.8%Grok STT · Aug 10: 5.3%Grok STT · Aug 11: 5.7%Grok STT · Aug 12: 5.1%Grok STT · Aug 13: 5.6%Grok STT · Aug 14: 6.3%Grok STT · Aug 15: 11.1%Grok STT · Aug 16: 6.4%Grok STT · Aug 17: 4.9%Grok STT · Aug 18: 12.9%Grok STT · Aug 19: 5.5%Grok STT · Aug 20: 4.6%Grok STT · Aug 21: 4.5%Grok STT · Aug 22: 6.3%Grok STT · Aug 23: 5.4%Grok STT · Aug 24: 13.7%Grok STT · Aug 25: 5.2%Grok STT · Aug 26: 4.9%Grok STT · Aug 27: 4.4%Grok STT · Aug 28: 5.9%

Time to Final Segment by dataset

Grok STT by test conditionMilliseconds · lower is better · best condition firstGrok STT's Time to Final Segment on each benchmark dataset.
  1. WildASR accents164 ms
  2. WildASR reverb177 ms
  3. WildASR phone codec186 ms
  4. WildASR clean197 ms
  5. WildASR far-field200 ms
  6. WildASR noise gaps200 ms
  7. PipeCat (production)202 ms
  8. WildASR clipping251 ms
Time to Final Segment per dataset, with the number of samples behind each figure.
DatasetTTFSSamples
LibriSpeech235 ms1
ProductionPipeCat202 ms14,937
AccentsWildASR164 ms1,438
CleanWildASR197 ms5,780
ClippingWildASR251 ms1,444
Far-fieldWildASR200 ms1,442
Noise gapsWildASR200 ms1,441
Phone codecWildASR186 ms1,441
ReverbWildASR177 ms1,398

Strongest condition: WildASR accents at 164 ms · weakest: WildASR clipping at 251 ms.

Limits of this comparison

Coval measures both the text it returns and how quickly its streaming results arrive through xAI's official API.

  • The service is evolving; xAI's official documentation remains the source for current languages, limits and feature availability.

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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