Birkby is a hamlet in the Allerdale district of the English county of Cumbria, historically within Cumberland, near the Lake District National Park. It is located on the A596 road, 1.6 miles (2.6 km) north-east of Maryport + 26.2 miles (42.2 km) south-west of Carlisle. In 1870-72 it had a population of 157.