Updated November 1, 2026
cdfacalc.com is a free calculator. It has no accounts, it never asks for your name or email address, and no advertising network runs on it.
The site uses Google Analytics to count visits and to see which features get used: the pages viewed, scrolling, links followed to other sites, file downloads, airport searches (the first 40 characters of what you typed), METAR lookups (the weather station identifier and whether the lookup worked), and whether the calculator produced a result. Google Analytics sets cookies (_ga and _ga_EGSTMN1MXZ) so it can tell a returning browser from a new one. Google's ad features are off: no advertising, no ad personalization and no Google Signals.
Visitors in the European Economic Area, the United Kingdom and Switzerland are asked first. Until you click Allow, Google Analytics does not load and nothing is sent to Google. Your choice is kept in your browser for 12 months; after that you are asked again. To change it, use Analytics settings at the bottom of the page: it removes the Google Analytics cookies and asks again.
The site reads the country Cloudflare reports for your connection only to decide whether to ask first. It does not store it.
Google's privacy policy: policies.google.com/privacy
The site runs through Cloudflare, which also counts visits with Cloudflare Web Analytics. Cloudflare Web Analytics sets no cookies.
The calculator remembers your gust choice (steady, peak gust, or steady plus half the gust) and, where you were asked, your Allow or Decline, in your browser's local storage. Neither is sent anywhere.
Use the phone number or email address at the bottom of the calculator page.