What this calculator does
Text-to-speech providers price in different units. Amazon Polly and most ElevenLabs API models charge per character, and some OpenAI voices are billed per audio token and quoted per minute. That makes a fair comparison awkward. This calculator converts everything to one baseline, cost per million characters, then projects your monthly bill and the cost of one finished hour of audio for each voice.
How the math works
The conversions rest on speaking pace. At the default 150 words per minute, and about six characters per word including the space after it, one minute of speech is about 900 characters. One hour is about 54,000.
- Characters per month come straight from your input, or from words × 6, or from minutes × words-per-minute × 6.
- Monthly cost = characters × price per million characters ÷ 1,000,000.
- Per-minute models are converted to a per-character price using the same pace, so changing the pace changes their relative position.
- The optional 15% retake buffer covers lines you regenerate because of a mispronunciation or the wrong emphasis. That is common in narration work.
Worked example
An independent author wants an audiobook of a 90,000-word novel. That is 540,000 characters, or about 10 hours of audio at 150 words per minute. On ElevenLabs v3 ($80 per million characters) it costs $43.20, about $4.32 per finished hour. On Amazon Polly Neural ($16 per million) the same book costs $8.64. With a 15% retake buffer those become $49.68 and $9.94.
For a narrated product the bigger question is usually voice quality, not price. Even the most expensive option here costs less than a single hour of studio narration. For high-volume apps, such as a voice assistant speaking every reply, small per-character differences add up quickly. Combine voice and language-model costs in the AI API cost calculator, or check how long your scripts are with the LLM token estimator.
Limitations
Prices are pay-as-you-go API rates. Subscription plans bundle a monthly character allowance that can make the effective rate lower or higher depending on how much of it you use. Free tiers are not subtracted: Amazon Polly includes a monthly free allowance in your first year, and ElevenLabs has a small free plan. Speaking pace varies by voice and language, which changes how many characters fill a minute. ElevenLabs was running a temporary discount on its v4 models when these prices were checked; it is excluded here. Confirm current rates on each provider's pricing page.