100 holiday voice-overs at 600 characters: $3.00 of Sume TTS

A hundred 600-character holiday ad voice-overs cost $3.00 on Sume TTS. The rate is $0.0475 per 1,000 characters, so one read is 600 × $0.0475 / 1,000 = $0.0285, which is billed as $0.03 after rounding up to the cent.

Spaces and punctuation count as characters, and a single transcript can be up to 20,000 characters. That makes a voice-over the cheapest step in a holiday ad pipeline, and rounding is the only thing worth watching.

How rounding changes the total

Without rounding, 100 reads of 600 characters are 60,000 characters, or 60 × $0.0475 = $2.85. With per-job rounding each read is $0.03, so the batch is $3.00. The extra $0.15 is the rounding. If you merge six short lines into one job of 600 characters, you pay $0.03 for one job, not 6 × $0.01 = $0.06 for six.

Count before you call

Put the counting in code so a budget check runs before the first paid call. This script totals the batch with the same rule as above.

import math

RATE_PER_1000 = 0.0475

def job_cost(text: str) -> float:
    raw = len(text) * RATE_PER_1000 / 1000
    return math.ceil(round(raw * 100, 6)) / 100

scripts = ["Last order day for gifts is the 18th. " * 15] * 100
lens = {len(s) for s in scripts}
total = sum(job_cost(s) for s in scripts)
print(f"{len(scripts)} jobs, lengths {sorted(lens)}, total ${total:.2f}")

Mistakes that cost more than the characters

The voice must match the language. If the language you send differs from the primary language of the voice, TTS returns 409 tts_voice_language_mismatch, and you pick another voice rather than retrying. A script that runs longer than the video it goes under forces a re-render of the clip, which costs far more than the voice.

Use an Idempotency-Key for each read, and take the result by webhook when you run a hundred at once. The jobs and webhooks docs describe the status route and the signed terminal event.

Where TTS sits in the whole ad

At $0.03 a read, voice is about 4% of a $0.75 six-second Omni Flash clip at 720p. The big lines are video seconds and avatar seconds, so spend your attention there, and use TTS freely to test script variants.