The six-month rule is not universal
Many travellers use six months as a safe planning shortcut, but official rules vary. Some destinations require validity for the planned stay, some require extra months beyond departure, and some add limits based on when the passport was issued.
That is why EntryAtlas only gives a full calculator pass when a nationality-specific rule has been verified for the selected destination.
Schengen is a useful example
For many non-EU nationals travelling to the EU, official EU guidance says the passport should be valid for at least three months after the intended departure and should have been issued within the previous 10 years.
The important point is not to generalise that rule to every destination. It is one regional rule set with its own scope.
Check the rule close to travel
Validity requirements can change, and they can interact with visas, residence permits and transit rules. Use the calculator as a planning check and follow the linked official source before paying for a non-refundable trip.