ElevenLabs vs Cartesia: Text-to-Speechlatency & accuracy
Measured head-to-head, not marketing: ElevenLabs currently leads both measured axes: median TTFA and Word Error Rate. Independent data, refreshed daily, on identical inputs. Voice quality and price are not measured.
ElevenLabs or Cartesia: which is better?
Each provider's best model on each measured axis, last 7d. Lower is better on both:
| Axis | ElevenLabs (best model) | Cartesia (best model) | Measured winner |
|---|---|---|---|
| Speed: median TTFA | eleven_flash_v2_5 · 188 ms | sonic-3.5 · 271 ms | ElevenLabs |
| Accuracy: avg WER | eleven_v3_conversational · 4.3% | sonic-3.5 · 5.9% | ElevenLabs |
Not measured here: voice quality / naturalness and price. Treat those as vendor claims until measured. Full leaderboard context: the independent text-to-speech benchmark →
Every ElevenLabs and Cartesia model, measured
All benchmarked models from both providers on the same pinned dataset, ranked fastest-first (median TTFA), last 7d:
| Model | Provider | TTFA median | TTFA p95 | WER | Samples |
|---|---|---|---|---|---|
| eleven_flash_v2_5 | ElevenLabs | 188 ms | 485 ms | 6.8% | 910 |
| sonic-3.5 | Cartesia | 271 ms | 352 ms | 5.9% | 3,359 |
| eleven_v3_conversational | ElevenLabs | 360 ms | 518 ms | 4.3% | 3,359 |
Data by Coval
Coval sells voice-agent evaluation infrastructure. Numbers are a rolling 7d aggregate on a pinned dataset under production-realistic conditions. Openbenchmarks mirrors the results with attribution; methodology and runner are open-source.
ElevenLabs vs Cartesia: common questions
Is ElevenLabs faster than Cartesia for text-to-speech?
On the current 7d window, ElevenLabs's fastest model (eleven_flash_v2_5) has a median TTFA of 188 ms, vs 271 ms for Cartesia's fastest (sonic-3.5), so ElevenLabs is faster on measured median latency. Distributions matter too: p95 is 485 ms for ElevenLabs vs 352 ms for Cartesia.
Which is more accurate, ElevenLabs or Cartesia?
By Word Error Rate: ElevenLabs's best model (eleven_v3_conversational) averages 4.3%, vs 5.9% for Cartesia's best (sonic-3.5). ElevenLabs leads on measured accuracy. Lower is better; WER is measured on identical inputs under production-realistic conditions.
Which should I pick, ElevenLabs or Cartesia?
ElevenLabs currently leads both measured axes (median TTFA and WER). Full per-model distributions are in the table below; voice quality / naturalness and price are not measured here.
Where does this data come from?
Coval sells voice-agent evaluation infrastructure. Every model runs the same pinned dataset under production-realistic conditions. The table is a rolling 7d aggregate, not a single job; Openbenchmarks mirrors it with attribution. Methodology and runner are open-source (Apache-2.0).