Gravel Calculator: Get the Tonnage Right Over Georgia Red Clay

Anyone who has watched a summer thunderstorm sheet off a Piedmont slope knows red clay doesn't forgive a thin layer of stone. Use this gravel calculator to size your order in cubic yards, tons and cubic feet, and read the mistakes below first, because most short or oversized orders start before anyone presses Calculate.

Where orders usually go wrong

Most of the time the arithmetic is fine and the inputs are off. Here are the slips we'd point out if we were standing in your yard with you.

• Entering the depth of the hole instead of the depth of the stone. If you dug 6 inches but plan 2 inches of topsoil back on the edges, only the stone depth goes in.
• Measuring feet and inches together. A patio that is 14 feet 6 inches should be entered as 14.5, not 14.6.
• Picking the wrong material. Graded aggregate base weighs more per yard than pea gravel, so the same hole needs more tons.
• Unticking the 5% box on a base. Stone you tamp or drive on packs down, and some always ends up in the grass.
• Forgetting that clay moves water sideways. A layer that looks deep enough on a dry day can be too thin once the clay under it is soaked and soft.
• Ordering one layer where two belong. A drive or patio usually wants a compacting base and a separate top or bedding layer, sized as two entries.

Using the gravel calculator, one field at a time

Start with the shape. Rectangle asks for a length and width in feet. Circle asks for a diameter in feet. Multiple areas lets you add up to five pieces, which handles a patio with a grill nook or a path that turns a corner.

Next comes depth, entered in inches between 0.25 and 24. Then choose your material from the list, decide whether to tick "add 5% extra for compaction & spillage", and press the button. Your estimate shows up as cubic yards, tons and cubic feet. If you'd like it sent to you, there's an Email my quote option right under the results.

What sits behind the figures

The tool multiplies your length and width in feet by your depth in inches, divides by 12 to get cubic feet, and divides that by 27 to get cubic yards. Tons come from multiplying the yards by the weight of the stone you picked. These are the weights it uses:

• Driveway or walkway gravel: about 2,800 lb a yard, 1.40 tons
• Pea gravel (3/8"): about 2,800 lb, 1.40 tons
• Crushed stone (#57, 3/4"): about 2,800 lb, 1.40 tons
• Crusher run or road base: about 3,000 lb, 1.50 tons
• River rock (1-3"): about 2,700 lb, 1.35 tons

Matching the stone to the job

Graded aggregate base, which you'll hear called GAB, is the standard base material around here, and on this site it's listed as GAB (Graded Aggregate Base). It packs down hard and gives a patio or pad something firm to sit on even after a week of rain. Crusher run does a similar job where you want a binding, compacting layer. Both use the 1.50 figure.

When water is the problem, reach for clean stone. #57 granite has no fines to clog, so it moves water through where red clay would hold it. For a decorative channel, river rock gives you the rounded look of a creek. Screenings go on top of a base to bed pavers and flagstone.

Three worked projects

These are made-up examples to show the math, not jobs from real customers.

A construction entrance for a home build

Picture a 40 ft by 14 ft pad of 3/4" crushed stone, 6 inches thick, so trucks don't track clay onto the road. That's 40 x 14 x 6 ÷ 12 = 280 cubic feet, or 10.37 cubic yards. At 1.40 tons a yard, it comes to 14.5 tons, or 15.2 tons with the 5% box ticked.

Base under a paver patio

Say the patio is 14 by 16 feet with 4 inches of GAB under it. 14 x 16 x 4 ÷ 12 = 74.7 cubic feet, which is 2.77 cubic yards. At 1.50 that's 4.15 tons, and 4.36 tons with the extra 5%. The bedding layer of screenings is a separate entry. An inch across the same patio is about 18.7 cubic feet, or 0.69 yards; screenings aren't in the weight list above, so check tons on the screenings product page.

A dry creek bed down a slope

This one's a channel 30 feet long, 3 feet wide and 6 inches deep, lined with river rock. 30 x 3 x 6 ÷ 12 = 45 cubic feet, or 1.67 cubic yards. At 1.35 tons that's 2.25 tons. On a steep run, larger stones at the bends help slow the water, and Large River Rock is sized for that.

Before you order

Here's the short list we'd run through with a neighbor:

• Measure twice, in feet, and convert inches to decimals.
• Enter each layer as its own calculation.
• Tick the 5% box for anything you'll compact.
• Pick a dump spot the truck can reach on firm ground. After a wet week, soaked clay can be too soft.
• Delivery is arranged at checkout by ZIP code.

When your numbers look right, open the product page to pick a date and quantity. Soil, sand and mulch on the same job have their own tools among the other material calculators. If you're stuck between two stones, reach us through the contact page and we'll help you choose.

Common questions

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