Landscape Material Calculator

About the Landscape Material Calculator

Most landscaping projects use more than one material. A new flower bed might need topsoil to raise it, compost to improve it and mulch to finish it. A paver path needs a gravel base and a bed of sand. Working out each material separately, at its own depth, with different bag sizes and some sold by weight, is tedious and easy to get wrong.

This landscape material calculator handles them all at once. Enter the size of the area and it gives quantities for mulch, topsoil, compost, decorative gravel and paver sand, each at its usual depth, which you can change or set to zero. For every material it shows cubic yards, the number of retail bags, and for soil, gravel and sand the weight in tons, so you can order from a store or a bulk supplier.

How to Use the Landscape Material Calculator

Enter the length and width of the area in feet.

Check the depth for each material, and set any you do not need to 0.

The Formulas

  area         = length × width
  cubic yards  = area × depth (in) ÷ 324
  bags         = ⌈cubic feet ÷ bag size⌉
  tons         = cubic yards × density (topsoil 1.1, gravel 1.4, sand 1.35)

Default depths and bag sizes: mulch 3 in, 2 ft³ bags; topsoil 4 in, 0.75 ft³ bags; compost 2 in, 1 ft³ bags; decorative gravel 3 in, 0.5 ft³ bags; paver sand 1 in, 0.5 ft³ bags.

Step-by-Step Example

A 20 × 10 ft area with every material at its default depth.

  area       20 × 10 = 200 ft²
  mulch      200 × 3 ÷ 324 = 1.85 yd³, 25 bags
  topsoil    200 × 4 ÷ 324 = 2.47 yd³, 2.72 tons, 89 bags
  compost    200 × 2 ÷ 324 = 1.23 yd³, 34 bags
  gravel     200 × 3 ÷ 324 = 1.85 yd³, 2.59 tons, 100 bags
  paver sand 200 × 1 ÷ 324 = 0.62 yd³, 0.83 tons, 34 bags

You would not normally use all five on one area. For a new planting bed you might keep topsoil, compost and mulch and set gravel and sand to zero.

Typical Depths

Mulch is spread 2 to 4 inches deep: enough to block light from weed seeds and hold moisture, but not so deep that it smothers roots or holds water against stems. Topsoil for new beds or lawns is usually 4 to 6 inches, more for raised beds. Compost is worked into beds at 1 to 3 inches. Decorative gravel suits 2 to 3 inches over fabric. Paver sand is screeded about an inch thick over a compacted base.

Layering a New Bed

Build a bed from the bottom up. Remove turf and weeds, loosen the existing soil, add topsoil to raise the level if needed, then spread compost and mix it into the top few inches. Plant, water well, and finish with mulch, keeping it a couple of inches away from stems and tree trunks. Order the materials together so the delivery can be tipped in the order you use them.

Bags Versus Bulk

Retail bags are convenient for small areas and for carrying through a house or up steps. They become expensive quickly: two yards of mulch is about 27 bags, while a bulk supplier sells it by the yard at a fraction of the price. As a rule, once any single material passes about two or three yards, a bulk delivery is worth pricing. Bulk soil and compost also tend to be better value because bagged products are often lighter, more processed blends.

Weight and Handling

Topsoil, gravel and sand are heavy, and their weight decides whether you can carry them in a car or trailer. Mulch and compost are much lighter, which is why they are sold by volume only. Wet materials weigh considerably more than dry, so plan to collect or spread them in dry weather where possible.

Paths and Patios

For a gravel or paver path the layers are different. A compacted base of crushed stone or crusher run comes first, usually about 4 inches, followed by either decorative gravel or about an inch of paver sand with pavers on top. The base material is calculated separately with the crusher run or gravel calculators, because it is compacted and sold by the ton. Use this calculator for the surface layers and set mulch, topsoil and compost to zero.

Estimating Cost

To turn quantities into a budget, multiply each material's yards by the supplier's price per yard, or its bags by the bag price, and add any delivery fees. Many suppliers deliver several materials on one truck for a single fee if they are loaded in separate compartments or bags, so ask before booking separate deliveries for each.

Seasonal Top-Ups

Mulch breaks down and gravel settles, so most beds need a top-up each year or two. An inch of fresh mulch over an existing layer is usually enough. Enter the top-up depth instead of the full depth to get a smaller order.

Understanding Your Result

The headline shows the area.

Each material line gives cubic yards, tons where relevant and the number of bags.

Materials with a depth of zero are marked as skipped.

When Should You Use This Calculator?

Use it when planning a new bed, border or path with several layers.

Use it to build a shopping list for a garden centre trip.

Use it to compare the cost of bagged and bulk materials for a project.

Common Mistakes

Using one depth for every material. Each layer has its own depth.

Mulching too deep. More than 4 inches can harm plants.

Forgetting to skip unused materials. Set them to zero.

Buying dozens of bags. Price a bulk delivery for larger jobs.