How many minutes of speech fit in one 20,000-character TTS request?

The limit and what it means in minutes

Every Sume TTS Router model accepts up to 20,000 characters per request. The number of minutes that fits depends on how fast the voice speaks your text, which varies by language, punctuation and the speed setting. Use the table as a planning range, then measure one real take.

A full 20,000-character request costs 95 cents on Sume. Sume TTS list price is 38 micro-dollars (0.0038 cents) per character; the billable price is list x 1.25, rounded up to whole cents per job. That is 0.00475 cents per character before rounding, so a 20,000-character request is 20,000 x 0.00475 = 95 cents.

Planning table

The minutes below are simple division of 20,000 by an assumed characters-per-minute rate. They are assumptions for planning, not measured outputs.

When the text is longer

Split on paragraph or sentence boundaries, never mid-sentence, send each part as its own job, and join the results. Joining is a separate Sume job that concatenates Sume-hosted audio sample-exactly with no re-synthesis (Timeline audio), at $0.01 per job and up to 1,800 seconds of output.

If the joined narration runs past 30 minutes, the 1,800-second cap means you need two joined files. Keep a log of the character count per part so you can predict minutes before you pay.

Keeping parts consistent

Read the finished job to see the model, voice, language and speed it used, and send the same values for the next part (Jobs and results). For repeatable output across parts, pin a concrete model id rather than relying on an alias that moves.

Measure one take first

Before you split a long script, generate a 1,000-character sample at the voice and speed you plan to use, and note the audio duration. Multiply to get a characters-per-minute figure for your text. That costs 1,000 x 0.00475 = 4.75 cents, rounded up to 5 cents, and saves guessing.

Speed settings change the result. A slower speed means fewer characters per minute and therefore more minutes in a full request. Record the speed you used next to the figure so future scripts use the same basis.

Why not always send the maximum

A full request is the cheapest per character only through rounding, and a single failure wastes the whole job. Sending 5,000 to 10,000 characters per job keeps retries cheap: a failed 5,000-character job costs at most 5,000 x 0.00475 = 23.75 cents, rounded up to 24 cents, while a retried 20,000-character job costs 95 cents. Pick part sizes that match how you review the script, one chapter or scene per job.