The amount of slates you need per square metre (m2) depends on which slate size you’re using. For example, if you’re using a 20×10 slate (500mmx250mm), you will require 21 slate per m2. A 24×12 slate (600mmx300mm) demands only 13 slate per m2. These figures tend to be slightly different throughout the industry, but we, along with all of our roofing merchants, believe the following figures to be the most accurate.

• 16×8 (400mmx200mm) = 29 slate per m2
• 16×10 (400mmx250mm) = 27 slate per m2
• 18×10 (450mmx250mm) = 23 slate per m2
• 20×10 (500mmx250mm) = 21 slate per m2
• 24×12 (600mmx300mm) = 13 slate per m2

If you know the surface area of your roof, you can use our simple Roof Slate Calculator to give you the exact amount of slates you require to complete the job.

Please Note: These figures do not allow for any wastage, therefore we recommend adding a further 5%-10% on top of your order to account for this.