Gemini TTS: 30 prebuilt voices or 150+? Which number to quote

Two Google pages give two voice counts for Gemini 3.8 Flash TTS, and both are correct for different things. The speech-generation guide lists 30 prebuilt voices, an extended library, and a cap of 200 custom voices per project. The changelog entry for the Sep 22, 2026 general availability says 150+ prebuilt and custom voices. Quote 30 when you mean the voices you can name today from the guide, 150+ when you quote the changelog, and never add the two together.

What each page says

The guide names a few of the prebuilt voices (Zephyr, Puck, Charon and Kore) and mentions voice replication for custom voices. The changelog describes the total pool, which mixes prebuilt and custom. Neither page says the 200-per-project cap and the 150+ pool are the same quantity, so a safe sentence keeps them apart.

How Sume selects a voice

Sume does not publish a voice count, because a voice is something you own. A TTS request picks a voice with avatar_id, avatar_handle or voice.id, and a voice.id must be a TTS voice UUID or voi_ followed by 32 hex characters. Anything else returns 400 invalid_voice_id before a job is queued or a charge is made. The router does not create a second voice namespace, so a voice you made for TTS 1.0 works with model: "sonic-3.6" unchanged.

That makes the comparison a question of workflow, not catalog size. If you need to pick from a menu of named stock voices, a large prebuilt list helps. If you need the same voice for every video in a series, an id you control is the thing that matters.

A rule for quoting vendor counts

Write the figure, its source page and the date you read it, as the table caption does. If two pages disagree, quote both with their scope. A reader who checks the changelog next quarter will find a different number, and a dated caption tells them why.

Checklist before you publish a voice count

Open the page you are citing and confirm the exact sentence. Note whether the count includes custom voices. Note the date, because Google dated the general availability entry Sep 22, 2026 and a later edit can change the figure. Then state the scope in the same sentence as the number: 'Google's changelog says 150+ prebuilt and custom voices' is safe, while 'Gemini has 150 voices' is not.

The same discipline applies to Sume's own numbers. The 20,000-character job limit, the 1-cent minimum and the 95-cent maximum all come from the repository docs and the generated price catalog, so cite them by name when you write about them.