How every calculator is verified
A calculator you can't check is just a guess with buttons. So every tool on this site follows the same rules:
- The formula is shown on the page, in full, next to the calculator that uses it — never hidden behind the result.
- Every real-world number is sourced. Platform fees, RPM benchmarks, withdrawal charges, formula coefficients — each one links to where it came from (official help pages, published studies, primary data), inline, at the claim.
- Worked examples are computed independently. Before a page ships, its examples are re-derived by hand and cross-checked against the page's own code, to the cent.
- Every page carries a "Formula last verified" date. Fee structures and benchmarks change; the date tells you how fresh the numbers are. When a platform changes its fees, the date resets only after we've re-checked against the source.
- Everything computes in your browser. No signup, no uploads, nothing stored — see the privacy policy for the whole (short) story.
What these tools are — and aren't
These are information tools: they do arithmetic honestly and show their work. They are not financial, medical, tax or legal advice, and no calculator knows your situation. The investing tools model assumptions you choose; the fitness tools estimate from population formulas with known error ranges (stated on each page). Where an input combination produces numbers with no real-world meaning, the tools say so instead of printing them confidently.
Found something wrong?
If a number looks off, a fee has changed, or a formula disagrees with a source you trust — tell us, and include the inputs you used. Accuracy reports are the most valuable mail we get.
Contact: mashxlabz@gmail.com
Who is behind this
Countworthy is built by MashxLabz, a hands-on software academy and studio. The same habits we teach — cite your sources, show your work, test your output — are the ones these pages are built with.