Calculator 04 / 08
Landscape rock calculator
Beds and borders are rarely one rectangle. Add each part of the bed — rectangles, circles, triangles or a known area — and get one total.
- Outputs
- yd³ · tons · tonnes · bags · cost
- Material basis
- Landscape rock · 105 lb/ft³ default, editable
- Method
- Formulas & sources
Measuring a bed that isn't a rectangle
Curved or angled beds are easier to measure in pieces: a rectangle for the straight run, a triangle for an angled corner, a circle around a tree. Where pieces overlap, trim one so the overlap isn't counted twice. If you already know the area from a plan, use Known area.
Worked example: border plus tree ring
| Border | 20 ft × 3 ft = 60 ft² |
|---|---|
| Tree ring | 6 ft diameter = 28.27 ft² |
| Total at 3 in | 88.27 ft² × 0.25 ft = 22.07 ft³ = 0.82 yd³ |
| + Waste 10% | 24.28 ft³ = 0.90 yd³ ≈ 1.27 US tons at 105 lb/ft³ |
Landscape rock vs. gravel
“Landscape rock” covers everything from 3/4 in decorative gravel to fist-size stone. Larger pieces need a deeper layer to cover the ground, and the air between them changes the weight per yard. We don't have a reliable published density for decorative rock, so the default is the general dry-gravel value source — replace it with the supplier's number when you pick a product. For rounded stone in drainage channels, use the river rock calculator.
Reading the result
Each line of the order sheet answers a different question. Read them in order: geometry first, then your allowances, then the quantity you can actually buy.
- Calculated volume
- Area × depth — pure geometry, before any allowance.
- + Compaction
- Extra loose material if the depth is a compacted depth. Shown only when set.
- + Waste
- Your margin for spillage, edges and uneven ground, applied after compaction.
- Purchase volume
- What to buy: volume × (1 + compaction) × (1 + waste). The exact figure.
- Estimated weight
- Purchase volume × the density shown. Only as accurate as that density.
- Bulk order
- Purchase volume and weight rounded up to the next ½ yd³ / ½ ton (½ m³ / ½ t in metric).
- Bags / cost
- Whole bags of the size you entered; cost = your price × the matching quantity.
What this calculator assumes
- Dimensions are the plan area that will actually be covered.
- Depth is an average across the area.
- Areas are flat; slopes aren't adjusted for.
- Density is a loose bulk density — a general published value unless you replace it.
- Waste and compaction are multiplied, not added.
- Bags are rounded up to whole bags; bulk orders up to the next ½ unit.
- Uses the general dry-gravel value. Decorative products differ widely; check the supplier's weight per yard or ton.
It can't see your site or your supplier's stone. What the calculators cannot know · Full methodology
Common mistakes with this calculator
Measuring a curved or L-shaped area as one rectangle
What goes wrong: Using the longest length and widest width counts ground that isn't there and over-orders.
How to avoid it: Split the area into rectangles, circles and triangles and add each one. See the measuring guide.
Depth entered in the wrong unit
What goes wrong: Typing 3 for a 3-inch layer while the depth unit is set to feet multiplies the volume by 12: a 10 × 10 ft area becomes 11.11 yd³ instead of 0.93 yd³.
How to avoid it: Check the unit beside the depth field. The calculators warn when a depth is over 24 in.
Choosing a depth thinner than the rock
What goes wrong: Large pieces in a thin layer leave gaps where the ground shows through.
How to avoid it: Try a deeper value and compare — the calculator shows the extra quantity immediately.
Questions
How much landscape rock do I need?
Measure each part of the bed, choose a depth that covers the soil for the rock size you're using, and add the areas here. The result gives cubic yards to order in bulk, tons if the supplier sells by weight, and bags for small areas.
How deep should landscape rock be?
Deep enough to cover the ground with the size of rock you've chosen: small gravel can be thinner, larger stone needs more depth. Try a few depths — the calculator shows how much each one changes the order.
Is weed fabric included?
No. The calculator estimates rock only. Fabric, edging and delivery are separate items.