| Kokoro is a frontier TTS model for its size of 82 million parameters. | |
| On the 25th of December, 2024, Kokoro v0 point 19 weights were permissively released in full fp32 precision along with 2 voicepacks (Bella and Sarah), all under an Apache 2 license. | |
| At the time of release, Kokoro v0 point 19 was the number 1 ranked model in TTS Spaces Arena. With 82 million parameters trained for under 20 epics on under 100 total hours of audio, Kokoro achieved higher Eelo in this single-voice Arena setting, over larger models. Kokoro's ability to top this Eelo ladder using relatively low compute and data, suggests that the scaling law for traditional TTS models might have a steeper slope than previously expected. | |
| Licenses. Apache 2 weights in this repository. MIT inference code. GPLv3 dependency in espeak NG. | |
| The inference code was originally MIT licensed by the paper author. Note that this card applies only to this model, Kokoro. | |
| Evaluation. Metric: Eelo rating. Leaderboard: TTS Spaces Arena. | |
| The voice ranked in the Arena is a 50 50 mix of Bella and Sarah. For your convenience, this mix is included in this repository as A-F dot PT, but you can trivially re-produce it. | |
| Training Details. | |
| Compute: Kokoro was trained on "A100 80GB v-ram instances" rented from Vast.ai. Vast was chosen over other compute providers due to its competitive on-demand hourly rates. The average hourly cost for the A100 80GB v-ram instances used for training was below $1 per hour per GPU, which was around half the quoted rates from other providers at the time. | |
| Data: Kokoro was trained exclusively on permissive non-copyrighted audio data and IPA phoneme labels. Examples of permissive non-copyrighted audio include: | |
| Public domain audio. Audio licensed under Apache, MIT, etc. | |
| Synthetic audio[1] generated by closed[2] TTS models from large providers. | |
| Epics: Less than 20 Epics. Total Dataset Size: Less than 100 hours of audio. | |
| Limitations. Kokoro v0 point 19 is limited in some ways, in its training set and architecture: | |
| Lacks voice cloning capability, likely due to small, under 100 hour training set. | |
| Relies on external g2p, which introduces a class of g2p failure modes. | |
| Training dataset is mostly long-form reading and narration, not conversation. | |
| At 82 million parameters, Kokoro almost certainly falls to a well-trained 1B+ parameter diffusion transformer, or a many-billion-parameter M LLM like GPT 4o or Gemini 2 Flash. | |
| Multilingual capability is architecturally feasible, but training data is almost entirely English. | |
| Will the other voicepacks be released? | |
| There is currently no release date scheduled for the other voicepacks, but in the meantime you can try them in the hosted demo. | |
| Acknowledgements. yL4 5 7 9 for architecting StyleTTS 2. | |
| Pendrokar for adding Kokoro as a contender in the TTS Spaces Arena. | |
| Model Card Contact. @rzvzn on Discord. |