Effective September 2026. Psychrometric Calculator is a free tool. Every calculation — including the psychrometric chart — runs entirely in your browser using JavaScript. The temperature, humidity, and pressure values you enter are never sent to, uploaded to, or stored on any server.
This site uses standard, anonymous Google Analytics (page views, referrer, country, browser type) and Microsoft Clarity (anonymized heatmaps and session recordings of on-page interactions, used to spot broken UI, not to identify you) to understand overall usage. No ad pixels or cross-site tracking are used.
If you buy the optional Pro upgrade (unlocks the batch calculator), our payment processor Stripe collects your email address and payment details to process the purchase — we never see or store your card number. We store your email and purchase record so you can restore Pro on another device later (via a 6-digit code sent to that email, no password). The batch calculator's inputs/outputs themselves are never uploaded or stored — only the purchase record is.
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support@psychrometric-calculator.com