Learning and careers decision
Books Calculator
A competent developer can build a lightweight replacement in a weekend; the product has no evident durable moat and relies on simple calculations and a small facts list.
Visit website↗Built by Marc Lou, who ships 32 products in this index
Not priced
No pricing page we fetched carried a figure, so there is nothing to compare against. The build side is still real.
$20one-off12 h to build
$0/mo1 h/mo upkeep
No published price to break even against.
Open-source builds that already do this
Every project below is open source and already does this job today. Fork one, self-host it, or take the parts you need - the build prompt further down assumes an empty file, and this is the shortcut past that. Licences differ; check the one on each card before you ship. All Books Calculator alternatives, with the arithmetic →
What a replacement has to do
- Enter reading speed and daily minutes → compute pages/words/books over a time window → view/save quick facts about famous books
What it still won’t have
- Polished analytics and usage tracking
- Cross-device user accounts and sync
- Professional UX polish and accessibility QA
- Curated, verified large book database and ongoing data corrections
- Commercial support and bug SLA
What remains hard
- Product polish and ongoing maintenance
First-year cost
No published price
Books Calculator does not publish a price we could read, so there is nothing to compare against. What building costs is below.
Money you would actually spend
Time you would spend
—
What you would spend
What we assumed
The verdict above measures whether you could build it. This one is only about money.
Runnable build prompt
Build a small single-page web app using React + Vite, TypeScript, and Tailwind; deploy as a static site to Vercel. In-scope features: 1) form to enter reading speed (WPM), daily minutes, and time window (1 month, 3 months, 6 months, 1 year, etc.), 2) calculation module that converts WPM + minutes/day into words/pages/books and shows results for selectable reading speeds, 3) small JSON-backed dataset of famous books (title, page count) with lookup and display, 4) persist last-used inputs in localStorage, 5) responsive UI and copy/shareable result link. Out of scope: user accounts, server-side storage, analytics, and cross-device sync. Include input validation, error handling for invalid inputs, unit tests for calculation logic (Jest), and basic end-to-end test (Playwright). Provide build and deployment scripts and README with instructions to run locally and deploy to Vercel.
How we checked
How the score was reached
- Build verdict base78
- An open-source build was found+5
- 3 cited sources+3
- 3/3 assessment runs agreed+4
- Evidence score90
The base comes from the verdict. Everything under it is a check that either happened or did not, and each one is a fact frozen in this record rather than a judgement made at render time - so the same evidence always produces the same number.
How scoring works →Cited sources · 3
Every page the run actually retrieved.
- official productBooks Calculator — official product page
- open sourcebayang/jelu
- open sourcepickles4evaaaa/mybibliotheca
Integrity checks
What held up, and what did not.