Landscaping and garden

Gravel Calculator

Enter the area and depth to get cubic yards, cubic meters and bags of gravel, plus tons if you add your supplier’s weight. Covers paths, drives and gravel beds, one layer at a time.

Units
ft
ft
in
Finished depth once spread and packed. Do one layer at a time.
%
Maine DEP’s road example adds 11% (x 1.11). Ask your supplier.
tons/cu yd
Tons per cubic yard for this stone. Weight varies by stone and size.
cu ft
For bagged gravel. Check the bag label.

Enter the area and depth, then press Calculate.

How we calculate

Gravel is ordered by volume (cubic yards) or by weight (tons). We work out the volume of each layer, add any extra you choose, and convert to tons only if you enter your supplier’s figure.

Volume (cu ft) = area (sq ft) x depth (in) / 12 With extra = volume x (1 + extra %) Cubic yards = cubic feet / 27 Tons = cubic yards x your supplier’s tons per cubic yard Bags = cubic feet / bag size (cu ft), rounded up

This matches the method in the Maine Department of Environmental Protection gravel road manual: “first calculate the volume needed in cubic feet (road length x width x depth), then convert to cubic yards. You also have to account for compaction. For example, to get 3 inches of compacted gravel on the road surface, you might need to multiply by 1.11.” Source: Maine DEP and Kennebec County SWCD, Gravel Road Maintenance Manual, April 2016 (PDF).

Why no default weight? The same manual says “a compacted cubic yard of gravel usually weighs around 1.6 tons”, but weight depends on the stone, its size and how wet it is. Ask your supplier for the figure for the product you are buying. Metric: 1 tonne per cubic meter = 0.843 tons per cubic yard.

Base layer and surface layer

Gravel paths and drives work best in layers. The Maine DEP manual says “an ideal road bed should have two layers; a base layer that provides strength and is free draining and a surface layer that is strong and dense, shedding rainfall and preventing it from infiltrating into the bed.”

It also explains why mixed sizes matter: gravel with “a range of different size gravel and sand” locks together (well-graded), while stones that are all the same size “are more apt to move around, causing rutting.” Run this calculator once per layer, with that layer’s depth, and order each material separately.

Cross-section of a gravel path: a dense surface layer over a free-draining base layer, with a slight crownCrown: higher in the middleSurface layerBase layerSoil
Calculate each layer separately with its own depth.

Drainage and crown

Water is the main enemy of a gravel surface. The Maine DEP manual says “to crown a road means to create a high point that runs lengthwise along the center of the road”, with each side sloped gently to the edge, and gives “a general rule for level or gently sloping gravel roads” of 1/2 inch of crown per foot of road width. For a 12 ft drive that is a 3 in high point in the middle (1/2 in x 6 ft each side).

Keep the edges clear so water can run off, and plan where it will go.

Decorative gravel in garden beds

Utah State University Extension treats gravel and crushed stone as inorganic mulch and suggests a depth of 2 to 3 inches. Under it, it recommends landscape fabrics “that allow air exchange and water infiltration”, laid in strips “overlapping strips about 4 inches”, and says plastic sheeting should be avoided. Source: Utah State University Extension, Water-Wise Landscaping: Mulch (PDF).

For bark and wood chips instead of stone, use the mulch calculator.

Worked examples

A 3 x 40 ft path, 4 inches deep: 3 x 40 x 4 / 12 = 40 cu ft, and 40 / 27 = 1.48 cubic yards. With 0.5 cu ft bags that is 80 bags.

The Maine DEP example: a 150 x 12 ft road surface at 3 inches is 150 x 12 x 0.25 / 27 = 16.67 cubic yards; with 11% extra for compaction, 18.5 cubic yards. If the supplier says 1.6 tons per cubic yard, that is 29.6 tons.

Materials checklist

  • Base gravel and surface gravel, calculated as separate layers
  • Landscape fabric that lets water through, if your plan uses it
  • Edging to keep stone out of the lawn and beds
  • Shovel, rake, wheelbarrow, and a hand tamper or plate compactor
  • Gloves, eye protection and sturdy boots

FAQ

How many tons are in a cubic yard of gravel?

It depends on the stone. The Maine DEP gravel road manual says a compacted cubic yard of gravel usually weighs around 1.6 tons; your supplier can give the figure for the product you buy.

How much area does a cubic yard of gravel cover?

At 4 inches deep, 27 x 12 / 4 = 81 square feet. At 2 inches it covers 162 square feet.

Why add extra for compaction?

Loose gravel packs down. The Maine DEP manual multiplies by 1.11 in its example to end up with 3 inches of compacted gravel. Set the extra box to 11 to do the same, or use your supplier’s advice.

How deep should gravel be?

It depends on the job and the soil. For decorative gravel in beds, Utah State University Extension suggests 2 to 3 inches. For drives and paths, build a base layer and a surface layer and ask a local supplier or contractor what suits your soil and traffic.

Can I use metric units?

Yes. Switch to Metric to enter meters and centimeters, the weight in tonnes per cubic meter, and bag sizes in liters.

Part of our outdoor-career toolkit: From office to outdoors.

Estimates only. Results are estimates based on the measurements you enter. Check local building codes and your product labels, confirm quantities with your supplier, and buy a little extra material. This is not professional or structural advice. Driveways and heavy loads need a base designed for your soil and traffic; ask a local contractor or supplier. Last checked: September 27, 2026.

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