Cookie Policy
Last updated: 2026.
This page explains what this site stores on your device, why, and how to stop it. It sits alongside our privacy policy, which covers everything else about data.
What cookies are
A cookie is a small text file a website asks your browser to keep, and hands back on your next visit. It lets a site recognize the same browser across pages and sessions.
“Cookies” here is shorthand for a few related technologies, all covered by this policy:
- Cookies — set by this site (first-party) or by a partner whose code runs on our pages (third-party).
- Local storage and session storage — browser storage that holds small preferences without sending them with every request.
- Pixels and tags — tiny invisible images or scripts that report a page view to a measurement or advertising service.
- Advertising identifiers — device-level identifiers our advertising partners may read.
The categories we use
Strictly necessary
These make the site work and are not optional. There is nothing to consent to, because without them the site would be broken or would forget the settings you deliberately chose.
| What it does | Where it is stored | How long |
|---|---|---|
| Remembers your light or dark theme choice | Local storage | Until you clear it |
| Remembers your imperial or metric unit preference | Local storage | Until you clear it |
| Remembers what you already typed into a calculator, so moving between calculators does not make you re-enter it (WCAG 2.2 criterion 3.3.7) | In-page memory for the current session only | Until you close the tab |
| Records your cookie consent choice, so we do not ask again on every page | First-party cookie or local storage | Up to 12 months |
| Security and abuse prevention, load balancing | First-party | Session or short-lived |
Calculator inputs stay on your device. They are not transmitted to us, and no one sees the dimensions of your driveway but you.
Analytics
Analytics tells us which answers get read, which searches return nothing useful, and where readers give up. We use it to decide what to write and fix, not to build a profile of you.
Analytics storage typically retains a pseudonymous identifier for up to 13 months, and shorter where a partner’s default is shorter. You can decline it, and everything on the site still works.
Advertising
Advertising is how this site pays for itself. Our advertising partners may set cookies and read advertising identifiers from your device to select ads, cap how often you see the same one, detect invalid traffic, and measure whether an ad worked. Some partners use this data across other sites they serve, which is what makes it “cross-context behavioral advertising.”
Advertising cookie lifetimes are set by each partner and commonly run from a few days up to 24 months. We do not list vendor names on this page because an outdated list is worse than none — email [email protected] for the current list of our advertising partners and we will send it.
Declining advertising cookies does not remove the ads. It makes them non-personalized, which is a worse business outcome for us and an entirely reasonable choice for you.
Google Consent Mode v2
We operate Google Consent Mode v2 to communicate your choice to advertising and analytics tools rather than merely blocking scripts and hoping.
Consent Mode carries four signals:
ad_storage— whether advertising cookies and identifiers may be stored;ad_user_data— whether your data may be sent to Google for advertising purposes;ad_personalization— whether your data may be used for personalized advertising;analytics_storage— whether analytics cookies may be stored.
Where consent is required before storage, all four default to denied until you make a choice, and tools that support Consent Mode fall back to cookieless, aggregated signals in that state. When you accept, the signals update to granted for the categories you accepted. When you decline or later withdraw, they return to denied and the associated cookies stop being set.
We also honor Global Privacy Control (GPC). If your browser sends a GPC signal, we treat it as an opt-out of the sale and sharing of personal information for advertising, without you having to click anything.
How to withdraw or change your consent
Use the cookie settings control on this site. It is reachable from the site footer, and reopening it lets you change any category at any time. Your new choice takes effect immediately for that browser and device.
Or clear this site’s cookies and local storage in your browser, which erases the stored consent record — the site will ask again on your next visit.
Because the record lives in your browser, a choice made in Chrome does not carry to Safari, and a choice made on your phone does not carry to your laptop. Clearing cookies clears the choice along with everything else.
Controlling cookies in your browser
Every major browser lets you block or delete cookies, and block third-party cookies specifically. The settings live here:
- Chrome — Settings, then Privacy and security, then Third-party cookies.
- Safari — Settings or Preferences, then Privacy. Safari blocks cross-site tracking by default.
- Firefox — Settings, then Privacy & Security, then Enhanced Tracking Protection.
- Edge — Settings, then Cookies and site permissions.
- Mobile browsers — under Settings, Privacy.
Blocking all cookies will break the parts of this site that remember your theme, your units and your consent choice, and you will be asked about cookies on every visit. Blocking only third-party cookies stops most advertising and analytics storage and leaves the site working normally.
Your device’s operating system may also offer an ad-tracking limit or an advertising-identifier reset, which applies across apps and browsers.
Do Not Track
We do not respond to the older Do Not Track browser header, because it was never given an agreed meaning that publishers and ad tech implement consistently. We do respond to Global Privacy Control, which was.
Changes
If we add a storage category or change how consent works, we will update this page and the “last updated” date. Material changes reset the consent prompt.
More information
Full details of what we collect, who receives it, and your rights — including the California “Do Not Sell or Share My Personal Information” right — are in the privacy policy. Questions go to [email protected].