What this page actually stores
Every time a conversion succeeds on any calculator on this site, the tool name, the input, the result, and a timestamp are written to this browser's local storage. There's no server involved and no account to sign into — the data lives in this specific browser, on this specific device, the same way a bookmark or a saved form value would. Opening the same site in a different browser or on a different device starts with an empty history, because there's nothing central to sync from.
Why it isn't capped at a handful of entries
Several well-known design and conversion tools treat "save more than a few results" as a paid feature — a free account might keep the last handful of items, with unlimited saved history locked behind a subscription. That model makes sense for a service storing data on someone else's server, where more storage has a real ongoing cost. Local storage in a browser doesn't have that same cost structure — the data lives on the device that created it — so there's no equivalent reason to meter it. This history keeps every conversion up to a generous technical ceiling (in the thousands), which exists purely to avoid unbounded growth in edge cases, not as a feature users are expected to run into or pay to lift.
Clearing it
The "Clear history" button above removes everything immediately and permanently — there's no undo, because there's no backup copy anywhere to restore from. Clearing browser data for this site through your browser's own settings (rather than the button above) has the same effect, since this history is ordinary local storage and nothing more. Private or incognito browsing windows don't persist it at all past the end of that session, since browsers discard local storage created in private mode when the window closes.
What it's useful for, and what it isn't
This is a scratchpad, not an archive — a quick way to glance back at what was converted a few minutes or days ago without retyping it, or to jump back to a calculator that was in use earlier in a session. It isn't a substitute for saving a value somewhere durable if it matters long-term: a design system's color tokens, a reference conversion for documentation, or anything that needs to survive clearing browser data, switching devices, or reinstalling a browser belongs in a file, a note, or the palette PDF export — something that exists independently of this one browser's local storage.