What is actually stored
Most of a cookie policy is about things this site does not do. There is no account, no session, no shopping basket and no personalisation, so there is no cookie that has to exist for the site to work. A visitor who refuses everything gets exactly the same calculators, at the same speed, with the same numbers.
What can end up on your device falls into three groups: one preference the site itself keeps, the record of your consent choice, and whatever the advertising and analytics services set once you have allowed them.
The theme preference
The button in the header cycles between following your system setting, light, and dark. Choosing light or dark writes that word to local storage in your browser, under a single key, so the next page opens the way you left it. It is read by a few lines of script before the page paints, which is what stops a dark-theme reader being flashed a white page. It is never sent to the server and it identifies nobody.
This is functional storage: it exists only because you asked for it, and it does exactly the thing you asked for. Setting the theme back to "system" deletes it. Clearing site data in your browser deletes it too, and the only consequence is that the site follows your operating system again.
The record of your consent
In the European Economic Area and the United Kingdom, a consent management platform certified under the IAB Transparency and Consent Framework asks whether advertising and analytics may load, and stores your answer so you are not asked on every page. That record is set by the consent platform, not by this site, and it is what the ad and analytics scripts read before they will run. Without it, or with a refusal in it, they do not run at all.
Advertising cookies
Once you have allowed advertising, Google AdSense may set and read cookies and similar identifiers on your device to select ads, to limit how often you see the same one, and to measure whether an ad was seen or clicked. They are set by Google, under Google's own policies, and their names and lifetimes are Google's to publish rather than this site's to guess at. This site does not read them and cannot read them.
Nothing you type into a calculator reaches them. The ad script is given the page, never the calculation, and the address it can see has already had its query string removed.
Analytics cookies
Where analytics is switched on and you have allowed it, Google Analytics 4 sets its own cookies to recognise a returning browser and to group requests into a visit. The site uses this to see which pages are read, how far down them people get, and how fast the pages are, which is what tells it where the site is failing. The privacy policy lists exactly which events are sent; none of them carries a figure from a form.
How to change or remove any of this
In the consent regions, the consent dialogue is the front door: it can be reopened to change your answer, and a refusal takes effect immediately for everything that has not already loaded.
Everywhere, clearing this site's data in your browser removes all of it at once, including the theme preference and the consent record. The dialogue then appears again on the next visit, because the answer it stored is what has just been deleted. Every current browser also lets you block third-party cookies wholesale, or block them for one site, and browser extensions that do the same are unaffected by anything here.
The theme preference alone can be removed without touching anything else by setting the theme back to "system".
What happens if you refuse
Every calculator continues to work. Nothing is held back, nothing is degraded and nothing asks again on the next page. What you lose is the theme following you between visits, if you cleared that too. What the site loses is the advertising that pays for it and the measurements that show which pages are worth improving, which is the honest reason it asks in the first place.