Arnaby is a village in Cumbria, England.
It is situated within the LA18 postcode district, which is within the Millom post town.
The full list of postcode districts within the Millom post town is as follows:
The Millom post town is within the Lancaster postcode area.
Administrative Ward: Millom Without
Administrative District: Copeland
Administrative County: Cumbria
Country: England
UK Parliament: Copeland
NHS Local Health Authority: North West
NHS Region: North, Midlands and the East