Cookie Policy
What cookies and browser storage we use across MolecularWeightCalculator.org and all of its tools, why we use them, and how you stay in full control.
Effective date: September 1, 2026
🔑 THE SHORT VERSION
We use very little: your browser’s local storage to save your recent calculations (on your device only — we never see them), a few essential cookies for basic site functionality, and — where enabled — standard analytics and advertising cookies from services like Google, which you can accept or reject. You can clear or block everything at any time from your browser.
📑 Table of Contents (click to expand)
1. What Are Cookies & Local Storage?
Cookies are small text files that websites place on your device to remember information — like your preferences or whether you’ve visited before. They can be “session” cookies (deleted when you close the browser) or “persistent” cookies (kept until they expire or you delete them). They can be “first-party” (set by us) or “third-party” (set by services we use, like analytics providers).
Local storage is a similar browser technology that lets a website save small amounts of data on your device — but unlike cookies, local storage data is never sent to any server automatically. It stays on your device until you or the website clears it. Our calculators use local storage, not cookies, for your calculation history.
2. Scope of This Policy
This Cookie Policy applies to the entire Site and every tool on it — the molecular weight calculator with all of its modes, and all related tools, calculators and resources we publish now or add in the future. Any new tool is automatically covered from the day it launches. This policy works together with our Privacy Policy and Terms & Conditions.
3. Types of Cookies We Use
| Category | Purpose | Examples | Duration | Can You Refuse? |
|---|---|---|---|---|
| Strictly Necessary | Core site functionality and security — the site can’t work properly without these | WordPress session/security cookies, hosting/CDN cookies | Session – 1 year | Blocked via browser only (site may break) |
| Functional (Local Storage) | Saves your recent calculations so you can re-run them — stored on your device only | mwcHist (calculation history) | Until you clear it | Yes — “Clear All” button or browser settings |
| Analytics | Anonymous, aggregate statistics about which pages and tools are used | Google Analytics (_ga, _gid, _ga_*) | 1 day – 2 years | Yes — consent banner / opt-out (Section 8) |
| Advertising | Ad delivery, frequency capping and (if consented) personalization — only if/where ads are shown | Google AdSense (_gads, _gcl_*, IDE, test_cookie) | 1 day – 13 months | Yes — consent banner / ad settings (Section 8) |
4. Calculator History (Local Storage)
Our tools save your last few calculations (e.g. the last 10 formulas) in your browser’s local storage so you can re-run them with one click. Important facts about this feature:
- ✅ Data is stored only on your device — it is never transmitted to us or anyone else;
- ✅ It contains only the formulas you entered — no personal information;
- ✅ You can erase it instantly with the “Clear All” button inside the tool;
- ✅ Clearing your browser data also removes it;
- ✅ Every current and future tool on the Site follows this same on-device principle.
5. Third-Party Cookies
5.1 Google Analytics
Where enabled, Google Analytics helps us understand — in aggregate — which tools people find useful, so we know what to improve and what to build next. IP anonymization is enabled where supported. Google’s use of data is governed by the Google Privacy Policy.
5.2 Google AdSense (if ads are displayed)
To keep every tool free, we may show ads via Google AdSense. Google and its partners may use advertising cookies to serve ads based on your visits to this and other websites. Where required by law, ads remain non-personalized unless you consent. Details: How Google uses cookies in advertising.
5.3 Embedded content
If a page ever embeds third-party content (for example a video), that provider may set its own cookies when you interact with it. We keep such embeds to a minimum.
6. Your Consent
Where required by law (for example in the EU/UK under GDPR/ePrivacy), non-essential cookies — analytics and advertising — are only set after you give consent through the cookie banner shown on your first visit. You can change or withdraw your consent at any time via the banner’s settings or by clearing cookies and revisiting the Site. Strictly necessary cookies and on-device local storage do not require consent, as they involve no tracking.
7. How to Manage or Delete Cookies
You have full control. Every major browser lets you view, block and delete cookies and local storage:
- Chrome: Settings → Privacy and security → Third-party cookies / Site settings → See all site data
- Firefox: Settings → Privacy & Security → Cookies and Site Data
- Safari: Settings → Privacy → Manage Website Data
- Edge: Settings → Cookies and site permissions → Manage and delete cookies
- Mobile browsers: look under Settings → Privacy (Chrome/Safari both support per-site clearing)
Blocking all cookies may affect basic site functionality, but our calculators will still work — they don’t need cookies to calculate.
8. Opt-Out Links
- Google Analytics opt-out add-on: tools.google.com/dlpage/gaoptout
- Google personalized ads: adssettings.google.com
- Industry opt-out (US): optout.aboutads.info
- Industry opt-out (EU): youronlinechoices.eu
9. Do Not Track
Some browsers offer a “Do Not Track” (DNT) signal. There is no industry-standard response to DNT yet, but our philosophy makes it largely moot: we do no cross-site tracking of our own, and your calculator activity never leaves your device regardless of any browser setting.
10. Changes to This Policy
As we add new tools or adopt new services, we may update this Cookie Policy. Changes appear on this page with an updated effective date at the top. Significant changes to non-essential cookies will be reflected in the consent banner where applicable.
11. Contact Us
Questions about cookies or this policy? We’re easy to reach:
MolecularWeightCalculator.org
Or use our Contact page — we reply within 24–48 hours.