AI Audiobook Cost Calculator: From Word Count to Plan Cost

This calculator turns your word count into an estimated number of finished audio hours, then into the credits, minutes, words or characters a tool bills, and finally into a plan cost. It is an estimate from published prices, not a measurement: NarratedIndie has not yet measured how many retakes a real book needs, so you set that margin yourself.

What the calculator does

You enter a word count, a words-per-finished-hour figure, a regeneration margin and a tool or plan and, for tools billed per character, a characters-per-word figure. The tool returns finished hours, minutes, the units that tool bills and the plan months or years needed. It covers ElevenLabs, Speechify Studio, WellSaid, Narration Box and Amazon Polly. Murf, LOVO and Google Cloud are listed but have no price, because their prices could not be read on 2026-11-08. The calculator prices narration only; the human-versus-AI decision is on human vs AI narration cost.

The formula

Every step is plain arithmetic. Every assumption is shown, and the book inputs can be changed:

1. hours = words / words per finished hour
2. minutes = hours x 60
3. billed units = a tool-specific conversion of minutes (below)
4. billed units with margin = billed units x (1 + margin / 100)
5. plan cost = plan price x the number of billing periods needed to cover the units

The tool-specific conversions are these:

• ElevenLabs: about 1,000 credits per minute, implied by the pricing page's approximate included minutes per plan (for example about 121 minutes for 121,000 credits). The page states no per-minute credit rate for text-to-speech.
• Speechify Studio: 1 credit per second of voiceover.
• WellSaid: minutes, used directly.
• Narration Box: words, used directly from your word count.
• Amazon Polly: characters, which is words x characters per word.

The default of 9,300 words per finished hour comes from a June 11, 2013 ACX blog post. It is old, and your narrator's pace and your voice's pacing will differ, so edit it. The default of 6 characters per word for Polly is our assumption, not a sourced figure.

A worked example, as an estimate

For an illustrative 90,000-word book at the 9,300 default, hours are 90,000 / 9,300 = about 9.68, which is 580.6 minutes. To reproduce these rows in the tool, set the regeneration margin to 25% and pick each plan. We use 25% here only to show how it works; it is an arbitrary input, not a real-world figure. With the margin, minutes become about 725.8.

All of these are our arithmetic on prices listed on 2026-11-08, with one clean pass plus the 25% example margin. ElevenLabs lists prices excluding tax; the other pages we read do not say. ElevenLabs' page says unused monthly credits roll over for up to two months (not on Free), WellSaid's says downloaded minutes reset each cycle and do not roll over, and we did not read carry-over rules for Narration Box, so a month-by-month total may differ. First-month promotions, free allowances and annual discounts are not applied. ElevenLabs' page flattened its plan table, and Narration Box's own annual discount is inconsistent on its page.

Limits

This is an estimate with several known gaps:

• Retakes are the biggest unknown and are entirely your input.
• Words per finished hour is a 2013 figure for human narration.
• Credit-to-minute rates are the vendors' approximations (for ElevenLabs, our inference from its included-minutes listing), not measurements.
• A tool's plan cost is not the whole cost. Your editing time, proofing and any mastering are separate.
• Price does not tell you whether a store accepts the audio. Check the route first, for example on the ElevenLabs review, the Speechify Studio review and the Murf review.
• LOVO and Google Cloud are covered in LOVO, WellSaid and Google Cloud.

Next steps

Pick the store route before the tool, because price alone does not decide where audio can be sold. See the AI audiobooks hub and the tools index. For current plans: ElevenLabs pricing and Speechify Studio plans.

Last verified 2026-11-08. Rules and prices change: check the linked primary page before you rely on this.