Landscape Rock Calculator
Decorative landscape rock by yards or tons
What is landscape rock calculator?
A landscape rock calculator answers the same question every garden-center customer asks: how many tons or cubic yards of decorative rock do I need to fill the bed. The volume math is just area times depth — but bulk rock is priced per ton, and the conversion depends on the rock type.
The default density is 95 lb/ft³, which works for most general-purpose 1-2 inch decorative landscape rock. Heavier rock — basalt, dense granite, river-jacks — runs 100-110 lb/ft³ and adds 10-15% to the tonnage. Lighter rock like lava and pumice falls to 50-70 lb/ft³. Always confirm with your supplier what the density is for the specific stock they have on hand; quarry sources can move 15-20% across regions.
What size to use? For beds and borders, 1-2 inch rock is the all-purpose pick — settled enough to stay where you put it, small enough to handle by shovel. For paths, 1/2 to 1 inch packs better underfoot but tracks indoors more. For features, 2-4 inch river rock looks more substantial. Anything finer than 1/2 inch acts more like a coarse mulch — fine for show-pieces but it migrates and disappears into soil over a few seasons.
Bulk vs bagged: at a home center, decorative rock comes in 0.5 cu ft bags at $5-12 depending on type. Past a single small bed, bulk delivery from a landscape supply yard is dramatically cheaper. A cubic yard equals 54 of those 0.5 cu ft bags — at $7 each that’s $378, versus $80-150 for the same yard in bulk. The calculator’s bag count makes this obvious; once you’re above 30 bags or so, pick up the phone and call a supplier.
The 10% waste factor default covers spread loss and minor edge over-fill. For path applications and driveway shoulders, bump to 15% — rock migrates into surrounding turf and soil with foot or vehicle traffic. Use heavy non-woven landscape fabric beneath all bed applications; without it, even quality rock disappears into the soil over 3-5 years and you’ll be ordering top-off material for years.
When to use a landscape rock calculator
- Bed mulch alternative — Replace seasonal mulch with permanent rock cover at 2-3 inches over fabric. Output in tons matches landscape supply pricing.
- Walkway and path surface — 3 inches of small rock or river-jacks over fabric makes a soft, permeable path. The bag-vs-bulk break-even falls early on long paths.
- Driveway shoulders and edges — Decorative rock on the shoulders dresses up a gravel driveway. Use the calculator across multiple narrow strips — they add up faster than expected.
How to use the Landscape Rock Calculator
- Measure the area — For rectangular beds, length times width. For irregular landscape areas, break into rectangles and add. For paths, length times path width.
- Pick a depth — 2 inches over landscape fabric is the standard for beds. 3 inches if you skip fabric, or for paths where foot traffic compacts the layer. Past 4 inches, you're paying for rock no one will see.
- Read the tonnage — Bulk landscape rock is sold by the ton (~$50-100/ton in 2026, depending on size and source). Output shows tons; 1 cu yd weighs about 1.28 tons at the default density.
- Apply waste factor — 10% covers spread loss and minor over-fill at edges. Bump to 15% for paths and shoulders where rock migrates into the surrounding turf or soil.
Worked examples
200 ft^2 bed at 3 in
Input: 10 ft x 20 ft x 3 in depth
Output: 1.85 cu yd / 2.38 tons (with 10% waste)Path surface, 3 ft x 60 ft at 3 in
Input: 3 ft x 60 ft x 3 in depth
Output: 1.83 cu yd / 2.35 tonsUse a metal or stone edging; otherwise rock migrates into the surrounding turf.
Driveway shoulders, 2 ft x 100 ft x 2 in (both sides)
Input: 2 ft x 200 ft x 2 in depth
Output: 2.47 cu yd / 3.18 tons