DIY - Gardens & Patio



This page allows you to input the length and width of a patio or any other area that you wish to pave, and calculates the number of slabs that will be needed to fill that bed, for a variety of standard sizes. An allowance is made for using the offcuts from each section, (if appropriate), and a small allowance is made for wastage.
Click on any of the links at the top of the page to reveal (or hide) more information about this calculator.


If you are reading this paragraph, then you probably don't have JavaScript installed/enabled on your computer.
At this point in time the calculators on this site are entirely dependent on JavaScript. Given enough time and money it is hoped to develop a version in the future which will be able to operate independently. Since JavaScript runs on your own computer, rather than on this server, it has been possible to set up this site much more quickly than if a server-side language was used, and it is possible to serve far more pages with the available bandwidth.
If you think that you can assist with this project in any way, then please visit the Support section and leave a message.


Length / Width
The furthest distance between opposite sides of the area to be paved. Width and Length should be measured in the same direction for the bed as for the slabs, regardless of the shape of the area to be slabbed. Since measurements across each slab need to be rounded up to the nearest whole slab, results may be slightly different if these dimensions are swapped.
Slab Size
The nominal size of the slabs to be used. For some natural materials this may be subject to variation, so double check the size of actual slabs.
Slab Price
Enter the price of a slab (if known) and a total price will also be calculated.
Bed Size
The size of the area that slabs will be laid on. If a layer of sharp-sand or other foundation is required, enter the depth of material required, and the total volume will be calculated as well.
Mortar Gap
The gap between slabs, usually filled with sharp-sand, or a sand-cement mix, similar to the layers of mortar between bricks.



  1. Fill in the length, width, gap and price boxes with the measurements of the area to be slabbed.
  2. Choose the correct units for all 'input' fields. You do not need to use the same units as the slabs are measured with, or the same units for width as length - all necessary conversions will be done for you.
  3. Click the 'CalcResult' button below the input fields
  4. A 'Results Area' will be displayed below.
  5. If you are trying to pave a complex area, split the job into rectangular sections, and input the values separately; a total will then be given.
  6. To do further calculations simply change any values in the input fields and click the 'CalcResult' button again. (Press the 'Clear Form' button if you want to empty all of the input fields.)
  7. Press the 'Clear Results' button if you wish to discard the first results, otherwise further calculations will be added into the same area.
  8. Click the 'CalcResult' button again
  9. Click the 'Print Results' button to display all current results in a new, printable window.
Slab measurement diagram
Slab measurement diagram
Dimensions of bed
Slab Details


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