The Slate Industry of North and Mid Wales

Traditional names and sizes of Slates


This page has also been translated into Polish, thanks to Valeria Alexandrova.
All sizes are in inches - length and then width

This system of naming slate sizes after female nobility was devised by General Hugh Warburton at Penrhyn quarry in 1738.  It soon became the industry standard and lasted for over two centuries.
Empress

26 x 16
Princess 24 x 14
Duchess 24 x 12
Small Duchess 22 x 12
Marchioness 22 x 11
Broad Countess 20 x 12
Countess 20 x 10
Small Countess 18 x 10
Viscountess 18 x 9
Wide Lady 16 x 10
Broad Lady 16 x 9
Lady 16 x 8
Wide Header 14 x 12
Header 14 x 10
Small Lady 14 x 8
Narrow Lady 14 x 7
Small Header 13 x 10
Doubles 12 x 6
Singles 10 x 5

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