Project guide
Garden & landscaping: beds, paths, patios, decks, and fences
A garden project usually mixes loose materials sold by volume with pieces sold by count. These calculators keep both straight, from a single bed of bark to a patio with a new fence around it.
Which calculator to use when
What the project involves
Loose landscaping materials such as mulch, bark, and gravel are sold by volume or by weight, in bags or bulk bags, so the key inputs are area and depth. A few centimetres of depth makes a large difference over a whole garden, and gravel is heavy enough that it is often sold by the tonne. Hard landscaping is counted instead: pavers per square metre including joints, deck boards per linear run including gaps, and fence panels and posts along a measured run.
Order matters outdoors. Fences and posts go in before planting along a boundary; patios and paths need their excavation, sub-base, and bedding layer before the surface goes down; and mulch is the last layer, spread over prepared and weeded beds. Planning in that order avoids walking machinery over finished beds or buying gravel twice.
Order of work
- Measure the boundary run and set out the fence first, sizing panels, posts, and post concrete together.
- Mark out patios and paths, then size pavers, sub-base, bedding sand, and edging with the Pavers & Patio calculator.
- For a gravel path or drive, use the Gravel calculator with the finished depth and the density your supplier quotes.
- For a deck, count surface boards from the deck area, board width, gap, and stock length; frame design is separate.
- Finish beds with mulch or bark at an even depth, using the Mulch & Bark calculator to convert area and depth into bags.
Common mistakes
- Guessing depth: 5 cm versus 8 cm of mulch is a 60% difference in volume over the same bed.
- Using a generic gravel density when your supplier quotes a different one for the stone you are buying.
- Forgetting that a fence of N panels needs N + 1 posts, plus extra posts at corners and gates.
- Sizing patio pavers without joints, then running short over a large area.
- Treating the deck board count as a full deck design; joist size, spacing, and footings need separate planning.
Common questions
FAQ
How deep should mulch or bark be?
Many gardeners use around 5–8 cm (2–3 in) on beds to suppress weeds and hold moisture, keeping it away from stems and trunks. Enter the depth you intend to spread; the calculator shows how quickly volume grows with depth.
Is gravel sold by volume or by weight?
Both. Small bags are often labelled by weight, while bulk deliveries may be quoted in tonnes or cubic metres. The Gravel calculator converts between them using a density you can edit, so use the figure your supplier gives for the stone you are buying.
Do I need the Post Concrete calculator if I use the Fence calculator?
No for a standard panel fence: the Fence calculator already includes post concrete for every post. Use Post Concrete separately for gates, pergolas, deck posts, or any posts that are not on a straight panel run.
Does the patio calculator include the sub-base?
Yes. Pavers & Patio estimates pavers or slabs, sub-base, bedding sand, and edging together, each at its own depth, so the whole patio can be ordered from one page.