About Calcometry

Calcometry is an independent project publishing free online calculators for fees, payroll, investing, fitness, education, construction, travel, and everyday math. Every tool runs entirely in your browser — no account, no uploads, no paywall.

Why this site exists

Most calculator searches land on pages buried in ads, outdated rates, or affiliate funnels. We built Calcometry so you can answer a specific question — "What do I actually keep after Etsy fees?" or "What hourly rate matches a $65k salary?" — with a clear formula, a worked example, and links to official sources where rates matter.

How formulas and rates are verified

Fee calculators trace to each platform's published fee schedule (Etsy, Stripe, PayPal, Amazon, and others). Each page lists those official documentation links so you can confirm numbers before pricing or payouts. Payroll, loan, and tax tools use standard arithmetic formulas cited on the page — they do not pull live tax tables or jurisdiction-specific rates unless you enter them manually.

Health-related tools (BMI, heart-rate zones, hydration) reference CDC, NIH, or WHO cutoffs where applicable and carry explicit "not medical advice" disclaimers. Fitness and health outputs are screening estimates, not diagnoses.

Unit converters use fixed conversion factors from NIST and international standards. All logic lives in typed TypeScript modules in our open repository so changes are reviewable.

Review schedule

Rate-sensitive pages — marketplace fees, payroll defaults, and sales-tax examples — are reviewed at least quarterly and whenever a platform announces pricing changes. Non-rate calculators (unit conversions, pure math) are updated when formulas or UX need fixing. Pages that cite external rates display a "last reviewed" date where applicable.

Site content last updated: July 30, 2026.

Affiliations and disclaimers

Calcometry is not affiliated with Etsy, Stripe, Amazon, PayPal, or any marketplace or payroll provider unless explicitly stated on a page. Results are estimates for informational purposes only — not financial, legal, tax, or medical advice. Always verify fees and rates on official platform websites before making business decisions.

Report an error or suggest a tool

Wrong formula, stale fee rate, broken link, or idea for a new calculator? Email us at [email protected]. Include the calculator URL, what you expected, and what you saw. We read every message and prioritize fixes that affect published rates or math.

See also our Contact page and Privacy Policy.