Privacy

The calculator stores nothing

Working out your cutoff happens entirely in your browser. Your bedtime, your drinks and your metabolism settings are never sent anywhere, and nothing is written to your device to produce a result. There are no accounts, and there is no server-side record of what you entered.

When you copy a share link, your settings travel inside the link's address. That is not storage on your device, which is why share links work before you have made any cookie choice. Anyone you send the link to can see the settings in it, so treat it as you would any other link you share.

Your language

This site is written in nine languages, and it will offer you one at the foot of the page if you appear to be reading another. The offer is only ever an offer: you are never redirected, and the page you asked for is the page you get.

Which language to offer is worked out from the languages your browser is set to, which are sent with every request you make to any site. If none of them is one we publish, we ask our hosting provider, Cloudflare, which country your IP address is in — a request to this site, not to anyone else, answered with a two-letter country code and nothing more. The address itself is not stored, logged by us, or used for anything else.

Nothing is saved unless you click. If you pick a language, that one choice is kept in your browser so you are not asked again, and the cookies page lists it. A guess is never saved, and neither is arriving on a translated page from a search result.

What needs your consent

The calculator needs nothing from you, so nothing about it is asked. Advertising is different: if you are in the EEA, the UK or Switzerland, Google's consent tool asks you before ads use anything on your device. Declining is one tap, sits beside accepting, and leads to exactly the same calculator.

Analytics

We count visits with a cookieless beacon that our hosting provider, Cloudflare, adds at the edge. It writes nothing to your device — no cookies, no storage of any kind — and there is no identifier that follows you between visits. What it reports is the page address, the referrer and how quickly the page loaded.

What you enter into the calculator is not sent anywhere. It is held in the page address so that share links work, and the beacon does not report those updates. The one case worth naming: if you arrive on a link somebody shared with you, the settings that link carries are part of the address counted for that visit.

Advertising

Ads are served by Google AdSense and keep the tool free. If you consent, they may be chosen using information about you. If you decline, they are chosen from the page you are reading instead — you still see ads, they simply earn less. Google's script also saves one setting relating to the consent message itself, named on the cookies page.

Google still receives the ordinary information any web request carries, such as your IP address and the page you are on, and uses it for fraud prevention and to decide which ad fits the page.

Your choices

You can change or withdraw your consent at any time through Google's consent tool, and withdrawing is as easy as granting. Nothing on this site is conditional on your answer: the calculator works identically either way.