Roof Tile Calculator: How Many Roof Tiles Do I Need?

Whether you’re replacing an existing roof or installing a brand-new roof on a new build, calculating how many roof tiles you’ll need can be a real nightmare. It’s absolutely vital to choose the correct tile for your project and buy the right amount. Otherwise, your project may not be completed on time or within budget. This is by far one of the most common issues our customers need help with, as they aren’t sure how many roof tiles they’re going to need. Working this out can be tricky, as it depends on a number of factors including roof size, pitch, and more.

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How to Use Our Roof Tile Calculators

By far the easiest way to figure out how many roof tiles you need is to use one of our innovative calculators. We’ve designed them to work with both metric and imperial units, and you just need to enter a few simple measurements to find out how many tiles and other materials you need for your project. These include your roof’s pitch, as well as its width, and length.

To use our roof tile calculators, simply visit the product page of the tile you’d like to use on your roof. If a bespoke calculator is available for that product, you’ll see a button prompting you to calculate how many tiles you need. Alternatively, you can choose from the list of calculators below.

Plastic Roof Tile Calculators

Tapco Slate Synthetic Roof Tile

Britmet LiteSlate Synthetic Roof Tile

Guardian Slate Synthetic Roof Tile

Eco Slate Synthetic Roof Tile

Metal Roof Tile Calculators

Britmet Plaintile Metal Roof Tile

Britmet Slate 2000 Metal Roof Tile

Britmet Ultratile Metal Roof Tile

Britmet Villatile Metal Roof Tile

Britmet Profile 49 Metal Roof Tile

Britmet Lightweight Metal Roof Shingles

Calculating How Many Roof Tiles You Need Yourself

If a calculator isn’t available for the roof tile you want, you’ll have to work out how many tiles you need for your roof yourself. If the manufacturer has provided tile coverage per square metre, all you need to do is multiply this by your roof area.

Roof Area (m2) x Tiles per Square Metre

For example, Envirotile Plastic Tiles require 11.9 tiles per square metre at a roof pitch of 30 degrees. Therefore, for a roof with an area of 60 square metres:

60m2 x 11.9 = 719

To be on the safe side, we’d suggest accounting for at least 5% wastage in your project. This will cover materials damaged in transit, on site, or where tiles have to be cut to fit. Therefore, we’d suggest purchasing 755 tiles for this project.

However, if the tile coverage has not been provided, you’ll have to do a little more work. To calculate how many tiles you need for your roof, you’ll need the following measurements:

  • Roof Area
  • Roof Pitch
  • Rafter Length
  • Cover Width of your chosen tile
  • Batten Gauge of your chosen tile
  • Headlap of your chosen tile

How to Calculate Your Roof Area

If your roof is a classic rectangular gable design, it’s easy to calculate the square meterage of your roof. Simply multiply the length of your roof by the slope height, and then double the answer.

(Roof Length x Roof Slope Height) x 2 = Roof Area (m2)

For example, if your roof length is 8m and your roof slope height is 6.5m:

(8m x 6.5m) x 2 = 104m2

If your roof is an unconventional shape, we’d recommend breaking it up into individual squares or rectangles. You can work out the square meterage of these areas separately and then combine the totals at the end for your total roof area. Calculating your roof area correctly will allow you to order the correct amount of roof tiles and minimise any wastage or lost time.

Learn More: How to Calculate Roof Area

How to Work Out the Pitch of Your Roof

Calculating your roof’s pitch is easy enough, as long as you have a measuring tape, spirit level, and calculator to hand, as well as access to your loft space.

You’ll need to know the size of your roof’s Rise (the height of your apex above the structure wall), along with the Run (the distance between the apex and the wall).

Roof Pitch = (1 ÷ Tangent (Rise ÷ Run))*180/π

For example, let’s say you have a roof with a rise of 10m and a run of 8m:

  1. 10 ÷ 8 = 1.25
  2. 1 ÷ 1.25 = 0.8
  3. 8 x 180/π = 45.8366…
  4. Therefore, your roof pitch is 45.84°!

Learn More: How to Calculate Roof Pitch

How to Calculate Rafter Length

Although you might not know it, one half of a pitched roof actually makes a right-angled triangle. This means that we can use Pythagoras’ Theorem to work out the length of our rafters.

a2 + b2 = c2

If we assume that our run is 5m, and our rise is 8m, then using the above formula we get:

52 + 82 = 89

Then, if we find the square root of our answer…

√89 = 9.43

Therefore, our rafter length is 9.43 metres!

Learn More: How to Calculate Rafter Length

Calculating How Many Tiles You Need for Your Roof

roof tile calculator

Now we can bring it all together.

  1. A ÷ X = D (Number of Tiles Needed for One Row Across the width)
  2. C ÷ Y = E (Number of Rows Needed)
  3. D x E = F (Number of Tiles Needed for One Side of the Roof)
  4. F x 2 = Total Number of Tiles Needed

For our example, we’re going to use a standard gable roof with a length of 10m (A), 5m width (B), a pitch of 25°, and a rafter length of 2.575m (C).

We’re also going to use the Britmet Slate 2000 as our example, which has a cover width of 1.25m (X), and a batten gauge of 0.369m.

  1. 10m ÷ 1.250m = 8 (Number of Tiles Needed for One Row)
  2. 585m ÷ 0.369m = 8 (Number of Rows Needed, Rounded Up)
  3. 8 x 8 = 64 (Number of Tiles Needed for One Side of the Roof)
  4. 64 x 2 = 128

If we account for 5% wastage and round up, this means we’ll need 135 tiles for our project.

If you’d like to do the above calculations yourself for a different product, take a look at the Technical Data we provide on each product page for more info.

Ready to Use Our Roof Tile Calculator?

Now that you’ve determined the size and pitch of your roof, it’s time to use one of our roof tile calculators. Simply choose from the list below, or click the grey calculator button on your chosen tile’s product page.

You may also find it useful to have the measurements for your ridges, hips, verges, and valleys, as this will allow us to make a more accurate calculation. To measure these, you simply need to use a tape measure to find out the length.

Plastic Roof Tile Calculators

Tapco Slate Synthetic Roof Tile

Britmet LiteSlate Synthetic Roof Tile

Guardian Slate Synthetic Roof Tile

Eco Slate Synthetic Roof Tile

Metal Roof Tile Calculators

Britmet Plaintile Metal Roof Tile

Britmet Slate 2000 Metal Roof Tile

Britmet Ultratile Metal Roof Tile

Britmet Villatile Metal Roof Tile

Britmet Profile 49 Metal Roof Tile

Britmet Lightweight Metal Roof Shingles

In Closing

If you’ve got any more questions about calculating how many tiles you need, working out the size of your roof area, or using our calculators, please get in touch. Our experienced customer service team will be able to help you, no matter the query. Call them on 01295 565 565, email sales@roofingmegastore.co.uk, or use the handy live chat below.