Slate Roof Tile Calculator
Pick a roof shape from the dropdown, set dimensions & pitch, then choose a slate preset.
1) Roof Shape
2) Dimensions & Pitch
3) Slate Preset (editable)
Results
Slate Roof Tile Calculator Guide (UK 2025)
The Slate Roof Tile Calculator helps you estimate total roof area, number of slates and overall weight for the five common roof shapes — gable, hip, pyramid, mansard and mono-pitch. Use this guide to understand sizes, pitch, headlap and simple install tips before you order.
How the Calculator Works
Pick your roof shape, enter length, width and pitch (or a known area). Choose a slate preset such as 500×250 or 600×300, and add a sensible waste allowance. Mansard roofs are split into lower and upper slopes for better accuracy.
Common Slate Roof Shapes
| Shape | Where Used | Notes |
|---|---|---|
| Gable (pitched) | Most houses | Simple, efficient drainage, easy estimating. |
| Hip | Detached homes | All sides slope — tidy look, wind-resistant. |
| Pyramid | Square plans, turrets | Four equal slopes to a point. |
| Mansard | Townhouses, loft gain | Steep lower + shallow upper slopes. |
| Mono-pitch | Lean-tos, extensions | Single slope, modern feel. |
Slate Sizes, Coverage & Weight
| Slate Type | Size (mm) | Typical Tiles/m²* | Approx. kg/tile |
|---|---|---|---|
| Natural Slate | 600×300 | 13–15 | ~2.1 |
| Natural Slate | 500×250 | 20–22 | ~1.3 |
| Natural Slate | 400×250 | 26–29 | ~1.0 |
| Synthetic / Fibre-cement | 600×300 | 11–13 | ~1.0 |
*Coverage varies with headlap (overlap of courses) which depends on pitch and exposure. Always check the manufacturer’s tables.
Pitch, Headlap & Minimums
- Typical slate roof pitch is 30–45°. Many products specify a minimum 25–30°.
- Headlap increases as pitch falls. Common headlaps are 75–100 mm for domestic roofs.
- Coastal, exposed or high-wind sites may require larger headlap and extra fixings.
Quick Cost Snapshot (UK 2025)
| Item | Unit | Typical Range (ex VAT) |
|---|---|---|
| Natural slate 500×250 | per m² (tiles only) | £28 – £55+ |
| Synthetic/fibre-cement slate | per m² (tiles only) | £18 – £35 |
| Roofing battens (graded) | per m | £0.80 – £1.40 |
| Breather membrane | per m² | £1.20 – £2.50 |
| Lead/flashings allowance | per linear m | £10 – £25 |
| Labour (2-person team) | per day | £300 – £500 |
All-in reroofing costs vary widely by access, scaffolding, details and region.
Example Quantities (Illustrative)
| Roof Area | Slate Choice | Tiles/m² | Waste | Total Tiles* | Approx. Weight |
|---|---|---|---|---|---|
| 80 m² gable | 500×250 natural | 20.5 | 10% | ≈ 1,804 | ≈ 2,345 kg |
| 120 m² hip | 600×300 natural | 13.3 | 10% | ≈ 1,759 | ≈ 3,694 kg |
| 50 m² mono | Synthetic | 12.0 | 8% | ≈ 648 | ≈ 648 kg |
*Tiles = Area × tiles/m² × (1 + waste). Weight = Tiles × kg/tile. Use the calculator for your exact geometry and pitch.
Install Basics
- Start at eaves, set gauge from headlap, and stagger vertical joints.
- Use stainless or copper nails. Fix each slate per manufacturer instructions.
- Cut with slate cutter/guillotine or diamond blade; pre-punch nail holes — don’t hammer through.
- Keep valleys, ridges and penetrations (flues, roof windows) watertight with correct flashings.
Affiliate Tools & Materials
- Natural & Synthetic Slates – Travis Perkins
- Breather Membrane – Screwfix
- Slate Cutters & Nibblers – Amazon
- Roofing Battens – Amazon
Disclosure: Some links may be affiliate links that help support SmartBuildCalc at no extra cost to you.
Related Calculators
Frequently Asked Questions
How many slate tiles per m²?
As a quick guide: 600×300 ≈ 13–15/m², 500×250 ≈ 20–22/m², 400×250 ≈ 26–29/m². Check the supplier’s charts for headlap and exposure.
What pitch should I use?
30–45° is common. Many slates quote a minimum of ~25–30°. Lower pitches need larger headlap and stricter detailing.
How much waste should I add?
5–10% for simple roofs; 10–15% for complex shapes with hips/valleys and lots of cutting.
Do I need special nails?
Yes — stainless steel or copper to avoid corrosion. Follow the manufacturer’s fixing schedule.
Note: Always follow UK regs and manufacturer data sheets for your exact product, site exposure and detailing.
