E2 TTS

Closed weights Microsoft 335M parameters September 2024

No estimate

No hardware requirements for this model

The weights for this model have not been published, so it cannot be downloaded or run on your own hardware at any size. It is reachable only through its provider, and no graphics card changes that.

On record

Full specification

Everything on record for this model. Most of it describes how it was trained rather than how it runs — useful context for judging how much work went into it, and how it compares with models built at a different scale.

Origin

Who built this model, where, and when it was published.

Organisation
Microsoft
Organisation type
Industry
Country
United States of America
Published
12 September 2024
Authors
Sefik Emre Eskimez, Xiaofei Wang, Manthan Thakker, Canrun Li, Chung-Hsien Tsai, Zhen Xiao, Hemin Yang, Zirun Zhu, Min Tang, Xu Tan, Yanqing Liu, Sheng Zhao, Naoyuki Kanda

What it does

The problem areas the model was built for. A model can carry several of each.

Domain
Speech
Task
Text-to-speech (TTS), Speech synthesis

Size

How large the model is and how much data it was trained on. Parameters are the figure that decides whether it fits on a given graphics card.

Parameters
335M

"The architecture incorporated U-Net [23] style skip connections, 24 layers, 16 attention heads, an embedding dimension of 1024, a linear layer dimension of 4096. The character embedding vocabulary size was 399.5 The total number of parameters amounted to 335 million"

Training data
245,760,000,000 tokens

"We utilized the Libriheavy dataset [30] to train our models. The Libriheavy dataset comprises 50,000 hours of read English speech from 6,736 speakers, accompanied by transcriptions that preserve case and punctuation marks." "We also used a proprietary 200,000 hours of training data to investigate the scalability of the E2 TTS model." "All models were trained for 800,000 mini-batch updates with an effective mini-batch size of 307,200 audio frames." Token count estimate: 307,200 × 800,000 = 2…

Training compute

The arithmetic performed to train the model, measured in floating-point operations. It is a measure of what the training run cost, not of how fast the finished model answers you.

Training compute
4.9 × 10²⁰ FLOP

6 FLOP / token / parameter * 245760000000 tokens * 335000000 parameters = 4.939776e+20 FLOP

How it was established
Operation counting

Availability

Whether you can obtain the model and run it on your own hardware, which is what decides if any of the graphics-card figures on this page apply.

Weights
Closed — provider access only
Model access
Unreleased
Training code
Unreleased

How it is classified

Labels the source dataset applies when tracking notable models, and how confident it is in the entry.

Record confidence
Confident

Sources

Where this record came from and when it was last checked.

Reference
E2 TTS: Embarrassingly Easy Fully Non-Autoregressive Zero-Shot TTS
Last updated
28 November 2025

What the numbers mean

About this model

E2 TTS was published by Microsoft, in United States of America, in September 2024. The organisation is categorised as industry.

It works in Speech, and is recorded as doing text-to-speech (TTS), Speech synthesis.

Its weights were never published, so it can only be reached through its provider. No graphics card changes that.

What went into building it

Training it took roughly 4.9 × 10²⁰ FLOP of computation — a measure of what producing the model cost, not of how fast it answers.

It was trained on about 245,760,000,000 tokens of text.

Answers

E2 TTS — common questions

01

When was E2 TTS released?

E2 TTS was published in September 2024. Capability per parameter has improved considerably since, so a newer model of the same size is often the better use of the same hardware.

02

What is E2 TTS used for?

E2 TTS works in Speech, and is recorded as handling text-to-speech (TTS), Speech synthesis. These are the areas it was designed around; they describe intent rather than a hard boundary.

03

How much compute was used to train E2 TTS?

Around 4.9 × 10²⁰ FLOP. That measures what producing the model cost and says nothing about how quickly it answers once trained — inference speed comes from memory bandwidth, not from the training budget.

04

What GPU do I need to run E2 TTS?

None. E2 TTS is a closed model — its weights were never published, so it cannot be downloaded or run on your own hardware at any price. It is reachable only through its provider.

05

Is E2 TTS open source?

No. E2 TTS has not had its weights published, so it exists only as a service controlled by its owner.

06

How many parameters does E2 TTS have?

E2 TTS has 335M parameters. "The architecture incorporated U-Net [23] style skip connections, 24 layers, 16 attention heads, an embedding dimension of 1024, a linear layer dimension of 4096. The character embedding vocabulary size was 399.5 The total number of parameters amounted to 335 million". That figure is the total, and it is what decides how much memory the model needs — roughly half a gigabyte per billion at the compression most people use.

07

Who created E2 TTS?

E2 TTS was published by Microsoft, based in United States of America, categorised as industry.

Source

Original publication

Record last updated 28 November 2025

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