Why the site exists
A passport can be inside its expiry date and still be refused, and the reason is rarely obvious from the document itself. Since the UK left the EU, British travellers to the Schengen area have faced two separate passport tests: one measured from the date of issue and one measured from the date of expiry. They are easy to confuse, they fail independently, and the consequence of getting either wrong is being turned away at check-in.
Working it out by hand means reading a government page, finding the two rules, translating them into dates, and then doing the same again for the next destination. This site does the arithmetic in one step and then explains what it did.
How the checker works
You enter the issue date, the expiry date and the destination. The tool compares those dates against the published requirements for that country, including the minimum validity required on arrival or departure and, for Schengen destinations, the rule that the passport must have been issued less than 10 years before you arrive. It returns a clear verdict rather than a list of caveats.
Everything happens in your browser. Your passport dates are not sent to a server, not stored and not shared, because there is no server-side processing to send them to. Anything you save, such as a trip or a family member's dates, is held in your own browser's local storage and stays on your device.
Where the rules come from
The rules on this site are taken from GOV.UK, principally the foreign travel advice entry requirements for each destination and the passport guidance published by HM Passport Office, and from the European Commission's own pages for anything concerning the Schengen area, the Entry/Exit System and ETIAS.
Pages carry the date they were last checked against those sources. Where something could not be confirmed from an official source, the page says so rather than filling the gap with a plausible number. Fees, processing times and border schemes all change, and a confident wrong figure is worse than an admission that you should go and look.
What this site is not
This is not a government service. It is independent, and it has no connection to HM Passport Office, the Home Office, GOV.UK, the Foreign, Commonwealth and Development Office, any embassy or consulate, or any EU institution. It cannot process an application, look up an application, cancel a passport or issue a document. If you need any of those things, go to GOV.UK.
It is also not advice. The pages here are general information about how UK passport rules work. They cannot take account of your nationality, visa status, purpose of travel or previous travel history, all of which can affect whether you are admitted to a country. A result from the checker is not permission to travel.
The final decision always belongs to somebody else. Airlines decide whether to board you, and border authorities decide whether to admit you. Neither is bound by anything on this site, and both can apply rules more strictly than the published minimum.
How it is paid for
The site carries advertising, which is what keeps it free to use. Advertising cookies are set only if you agree to them, and the same applies to the measurement used to see which pages are worth keeping. You can change either choice at any time using the cookie settings link in the footer. The privacy policy sets out the detail.
Getting a correction made
If a rule here is wrong, or a fee has changed, or a check returns a result that does not match what GOV.UK says, that is worth reporting and it will be looked at. The contact page explains how, and what to include so the problem can actually be found.
Start with your own dates. The passport checker takes about twenty seconds, and the guide explains every rule it applies.