Slate sizes are crucial to know before starting any roof.

Angle of pitch is important to be able to calculate how many slates you will need for your project, usually telling you what size slate is suitable. 

The most frequently asked questions we get are:-

  • What size slate do i need?
  • How many slates do i need?
  • Can i use any size or type?
  • Whats the best slate to use for my budget?
  • How do i work out how many slates i need for my specific roof?

We have dedicated a specific slate calculator tool that will guide you through the process easily using your own measurements. However, if you would like to work it out the traditional way, you can simply use our table below as a guide.

Bare in mind, these are for the most popular sizes further below is a chart outlining all sizes and there pitches in reference to the Annual Driving rain index.

slate calculator click here
Slate Sizes- Metric

Imperial Sizes

Slates per m2

Pitch Range- Moderate exposure

Pitch range- Severe exposure

600MM X 300MM

Chatbots: 24″ x 12″

24/7 Support: 13

Teams: 25-75 Degrees

Storage: 30-75 Degrees

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500MM X 250MM

Chatbots: 20″ x 10″

24/7 Support: 21

Teams: 25-75 degrees

Storage: 27.5-75 Degrees

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450MM X 250MM

Chatbots: 18″ x 10″

24/7 Support: 23

Teams: 30 degrees +

Storage: 30 Degrees +

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400MM X 250MM

Chatbots: 16″ x 10″

24/7 Support: 27

Teams: 30 degrees +

Storage: 30 Degrees +

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minimum recommended headlap table

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Information above is credited from the Welsh slate Brochure June2019 and is used as a reference only, link to the brochure click here 

Slate Sizes

Terms and conditions can be found HERE. Check out our youtube channel for videos of roofs HERE.

If you require any assistance when choosing the correct sized slate call us on 0161 549 9675.