How to Calculate Gravel: A Complete Guide

Gravel is used for driveways, walkways, drainage beds, and as a base layer under patios and pavers. Unlike concrete or lumber, gravel is sold by both volume (cubic yards) and weight (tons), and the conversion depends on the material type. This guide explains how to calculate the right amount and order it correctly.

The Basic Gravel Formula

Start by calculating the volume of the area you need to fill:

Volume (cubic yards) = (Length x Width x Depth in feet) / 27

For example, a driveway 60 ft long, 12 ft wide, with a 4-inch gravel base:

1. Convert 4 inches to feet: 4 / 12 = 0.333 ft
2. Volume: (60 x 12 x 0.333) / 27 = 8.89 cu yd

Order approximately 9 cubic yards, plus a waste factor.

Converting Cubic Yards to Tons

Most suppliers sell by the ton. Conversion factors vary by material:

• Pea gravel: 1.4 tons per cubic yard
• Crushed stone (3/4 inch): 1.4 tons per cubic yard
• Crushed limestone: 1.5 tons per cubic yard
• River rock: 1.3 tons per cubic yard
• Decomposed granite: 1.5 tons per cubic yard

Using the example above with crushed stone: 8.89 x 1.4 = 12.4 tons. Ask your supplier for their specific weight, as moisture and grading affect density.

Common Depths by Application

• Driveway: 4 to 6 inches compacted, sometimes layered coarse-to-fine.
• Walkway or path: 2 to 3 inches over landscape fabric.
• Drainage bed: 6 to 12 inches of washed gravel around the drain pipe.
• Paver base: 4 to 6 inches of compacted crushed stone.
• Landscape cover: 2 to 3 inches for weed suppression.

When You Need This Calculator

• Homeowners building or resurfacing a gravel driveway who need to order the right number of tons.
• Landscapers installing walkways or drainage systems who need volume and weight estimates for multiple areas.
• Contractors preparing a base for patios or slabs who need to calculate the compacted gravel layer.

Material Types and Uses

• Crushed stone (angular): Compacts tightly. Best for driveways, road base, and under slabs. If you are pouring on top of the base, use the Concrete Calculator to estimate your slab volume.
• Pea gravel (rounded): Does not compact well. Best for paths, playgrounds, decorative fill, and drainage around fence post holes. The Fence Calculator can help you estimate how many post holes you need.
• River rock (1-3 inches): Decorative and good for drainage. Used in landscaping and dry creek beds.
• Decomposed granite: Compacts into a firm surface. Popular for patios and xeriscaping.

Common Mistakes to Avoid

• Forgetting compaction. Loose gravel settles 20 to 30 percent. To end up with 4 inches compacted, spread 5 to 6 inches loose.
• Using the wrong conversion factor. Not all gravel weighs the same. Confirm with your supplier to avoid shortages.
• Skipping landscape fabric. Without a barrier, gravel sinks into the soil and weeds push through. Use geotextile fabric, not plastic sheeting.
• Confusing yards and tons. Confirm the unit of sale before ordering. This is one of the most common ordering mistakes.

Pro Tips

• Order 10 percent extra for irregular shapes. Curved borders and sloped areas are hard to measure precisely.
• Ask about delivery minimums. Many suppliers require 3 to 5 tons minimum. Below that, the delivery fee may exceed the material cost.
• Compact in lifts. Spread and compact in 2-inch layers rather than dumping the full depth at once for a firmer result.
• Taper the edges. Grade gravel to taper at borders rather than creating a sharp lip. This reduces migration and makes mowing easier.

Frequently Asked Questions

How many tons of gravel do I need for a 10x10 area?

At 3 inches deep, a 10 x 10 ft area needs about 0.93 cubic yards, or roughly 1.3 tons of crushed stone. At 4 inches deep, that increases to about 1.23 cubic yards or 1.7 tons.

How deep should a gravel driveway be?

A gravel driveway should be 4 to 6 inches deep after compaction. For heavy traffic or soft soil, build up to 8 to 12 inches in layers: coarse base, middle layer, and fine surface, each compacted before the next.

How much area does a ton of gravel cover?

One ton of crushed stone covers approximately 80 to 100 sq ft at 3-inch depth, or 60 to 80 sq ft at 4-inch depth. Coverage varies by material type and stone size.