Gravel calculator

A gravel calculator turns three basic project inputs into an estimated order quantity before you call a supplier: your area dimensions, your desired depth, and your material type. Ordering too little can mean a second delivery fee and a project that sits half-finished. Ordering too much can leave you with extra material to move, spread, or haul away. A calculator helps reduce both problems by using a clear volume and weight estimate instead of a rough guess.

Crushed Stone Calculator handles that math for free, with no login required. Enter your dimensions, choose your material type, and get your estimated volume in cubic yards, weight in US tons, bag count, and optional cost in seconds. The built-in waste factor helps account for real-world losses such as spillage, uneven ground, and spreading. By the end of this article, you’ll understand how gravel calculators estimate results, which depth to use for common projects, how much extra to order, and how to estimate material cost before you call a supplier.

What a Gravel Calculator Does (and Why Manual Estimates Often Miss)

The ordering problem most people don’t see coming

Most homeowners who guess at a material order focus on area and completely forget about depth. Picture a homeowner planning to resurface a 40-foot driveway. They eyeball the space, decide “maybe 5 tons should do it,” and call the quarry. What they didn’t account for: their driveway is 12 feet wide, they want a 4-inch depth, and the stone they chose weighs 1.35 tons per cubic yard. The correct calculation, 40 × 12 × (4/12) = 160 cubic feet, divided by 27, multiplied by 1.35, puts the actual order at about 8 tons. They need roughly 60% more material than their original guess, and now there’s a second delivery fee coming.

Over-ordering creates a different headache. Two extra tons of crusher run won’t disappear on their own. You either pay to have the material hauled off or spend a weekend spreading it somewhere it doesn’t need to go. Neither outcome is acceptable when the right number was always available with a quick calculation.

How a gravel calculator converts your dimensions into a material order

The calculation chain works in three steps. First, your area dimensions and depth are multiplied together to get a volume in cubic feet, then divided by 27 to convert to cubic yards. Second, that cubic yard number is multiplied by the bulk density of your chosen material to get a weight in tons, because many suppliers sell by the ton, while others may quote by cubic yard or bag. Third, the tool uses the price unit you choose — per ton, per cubic yard, or per bag — to produce a material cost estimate.

A gravel volume calculator removes the need to know any of the intermediate conversion math. You enter feet and inches; the tool outputs volume, tons, and an optional cost estimate if you enter a price. For example, a 10-by-20-foot pad at 4 inches deep produces roughly 2.5 cubic yards, and the tonnage equivalent, without any manual conversion on your part. That’s the entire value of the workflow.

Where Crushed Stone Calculator fits in

Crushed Stone Calculator is a free, browser-based aggregate calculator that handles rectangular, circular, triangular, total-area, and multiple-area inputs. It supports multiple material types, from pea gravel and limestone to granite, crusher run, and river rock, each with its own bulk density value so the tonnage output is a closer estimate than a one-size-fits-all calculation. The adjustable waste factor gives you full control over your overage percentage, a feature many generic calculators skip entirely. It also displays the formula used to generate your results, so you’re never left wondering where the number came from.

The Three Inputs Every Accurate Estimate Depends On

Area dimensions and shape

For a rectangular area like a driveway or patio, you need length and width in feet. For a circular area like a round garden bed or fire pit pad, you need the radius or diameter. For a triangular section, you need the base and height. Any irregular project area can be broken into smaller segments using those three shapes, calculated separately, and added together for a total volume. If your driveway has a flared entrance or an offset bump-out, split it into two rectangles and run each one through the gravel calculator independently.

Depth: the input people most often get wrong

Depth is where manual estimates fall apart most often, because people plug inches directly into a cubic-yard formula without converting to feet first. A 4-inch depth is 0.33 feet, not 4 feet. If you forget that conversion and use 4 instead of 0.33 in your calculation, your estimated volume comes out twelve times higher than it should. That single mistake can turn a 3-cubic-yard order into a 36-cubic-yard disaster on paper.

A good calculator handles the inch-to-foot conversion automatically, which is exactly why using one beats doing the math by hand. Enter your depth in inches, and the tool takes care of the rest.

Material type and bulk density

Not all gravel weighs the same per cubic yard. Pea gravel is commonly estimated at about 1.30 tons per cubic yard, river rock at about 1.35 tons per cubic yard, crushed gravel and #57 stone at about 1.40 tons per cubic yard, limestone gravel and #411 stone at about 1.45 tons per cubic yard, and crusher run or granite gravel at about 1.50 tons per cubic yard. These are typical bulk estimating values, not fixed supplier guarantees. Actual delivered weight can vary by quarry, moisture, gradation, and compaction.

If your supplier gives you an exact density, enter it as a custom density for a closer estimate. Since many suppliers invoice by the ton, using the right density helps keep your order estimate closer to real-world conditions. For help choosing the right material, consult a guide to the best gravel for your driveway.

The Volume Formulas Running Behind the Results

Rectangular and triangular area formulas

The rectangular formula is straightforward: (Length × Width × Depth) divided by 27 equals cubic yards. All three dimensions must be in feet before you divide. For a triangular area, the formula adds one step: (Length × Width × 0.5 × Depth) divided by 27. The 0.5 accounts for the fact that a triangle covers half the area of its bounding rectangle.

Here’s a worked example. A 20-foot by 10-foot rectangular area at a 4-inch depth converts to 0.333 feet of depth. The math is (20 × 10 × 0.333) divided by 27, which gives approximately 2.47 cubic yards before waste. With a 10% waste factor, the order volume becomes about 2.72 cubic yards. At a typical crushed gravel density of 1.40 tons per cubic yard, that equals about 3.80 US tons.

Circular areas and the π conversion

For circular areas, the formula is (π × radius² × Depth) divided by 27. A circular gravel pad with an 8-foot diameter has a 4-foot radius. At a 3-inch depth (0.25 feet), that’s (3.14159 × 16 × 0.25) divided by 27, or roughly 0.47 cubic yards. The same 27-cubic-feet-per-cubic-yard conversion applies across all three shape formulas, which makes it easy to mix and match shapes when a project area is irregular.

From cubic yards to tons using bulk density

Once you have cubic yards, the tonnage conversion is: tons = cubic yards × bulk density in tons per cubic yard. Here are reference values for common materials:

• Pea gravel: approximately 1.30 tons per cubic yard
• Crushed limestone: approximately 1.45 tons per cubic yard
• Crusher run: approximately 1.50 tons per cubic yard (exact value varies by grading)
• River rock: approximately 1.35 tons per cubic yard

Using the right bulk density for your material is what separates a real tonnage estimate from a generic one. Crushed Stone Calculator applies individual density values per material type, which means its tonnage output is specific enough to share with your supplier, though confirming final quantities before delivery is always a smart call.

Recommended Depths for Common Project Types

Driveways and compacted base layers

A residential driveway built for light vehicles needs 6 to 8 inches of total gravel depth. Heavier loads, pickup trucks hauling trailers or regular delivery vehicles, call for 8 to 12 inches. The standard layered approach uses 4 to 6 inches of compacted crusher run as a base course, topped with 2 to 3 inches of angular surface stone such as #57 stone or another crushed driveway gravel.

Calculating each layer separately gives you a more accurate total material order and lets you specify the correct material for each layer when you call the quarry. For step-by-step installation and upkeep, see a guide on how to lay and maintain a gravel driveway, and for more depth-focused recommendations consult our Driveway Guides.

Patios, walkways, and drainage applications

Patio bases under pavers typically need 4 to 6 inches of compacted gravel to prevent settling and frost heave. Walkways carry less load and generally do well with 2 to 4 inches, depending on foot traffic volume. French drain trenches are a different situation: they usually need 12 to 18 inches of depth filled with a clean, open-graded stone like #57 that allows water to move freely around the perforated pipe. Each of these applications has a different depth requirement, which is why a gravel estimator with a built-in depth guide is genuinely useful for first-time builders who don’t yet know the standard recommendations.

Waste Factor: The Calculation Step Most People Skip

What waste factor actually accounts for

Waste factor is the overage percentage added on top of your calculated volume before you place the order. It covers several real-world losses: irregular terrain creates low spots that consume more material than a flat-area calculation predicts, some stone always spills during delivery, and material at the project edges gets pushed wide during spreading. A 10% waste factor adds 10% to your calculated volume, giving you a meaningful buffer against coming up short.

When to push the percentage higher

For a clean rectangular area with angular crushed stone and a smooth subgrade, 10% is usually a good starting point. Use 15% for irregular shapes, rough ground, sloped areas, or projects where material must be moved and spread by hand. For very uneven sites or compactable materials such as crusher run, you may need a larger allowance, but it is smart to confirm with your supplier or contractor before ordering too much. The calculator lets you adjust the waste factor so the estimate can match your site conditions.

From Cubic Yards to a Real Cost Estimate

Bags versus bulk delivery

Bag counts depend on both the bag weight and the density of the material. One US ton equals 2,000 lb, so one ton requires 40 bags if each bag is 50 lb. One cubic yard of crushed gravel at 1.40 tons per cubic yard weighs about 2,800 lb, which is about 56 standard 50-lb bags. For small projects, bagged material can be convenient. For larger areas, bulk delivery is usually easier and often more practical than handling dozens of individual bags.

Using a gravel calculator to estimate cost before you call the supplier

The cost formula depends on the price unit you choose: tons × price per ton, cubic yards × price per yard, or bags × price per bag. Gravel and crushed stone prices vary by material type, region, supplier, order size, and delivery distance. Urban areas and locations far from quarries may pay more, while areas with nearby stone sources may pay less. Local gravel price listings can give you a rough regional baseline, but the most accurate number will come from your supplier.

A gravel cost estimator lets you enter your local price per ton, per cubic yard, or per bag and get a project total instantly, so you can walk into the supplier conversation with a realistic estimate instead of a guess. Crushed Stone Calculator includes this cost step directly in the output.

Put Your Numbers to Work Before You Order

Accurate gravel ordering comes down to four things: the right area dimensions, the correct depth for your application, the actual bulk density of your material, and a realistic waste buffer on top. Each of those inputs changes your final tonnage significantly, which is exactly why a proper gravel calculator produces far better results than a rough mental estimate or a back-of-the-napkin calculation that ignores density and compaction.

Crushed Stone Calculator Blog and the calculator itself handle all of it for free in your browser: multiple material types with typical bulk density estimates, an adjustable waste factor, support for rectangular, circular, triangular, total-area, and multiple-area inputs, and a transparent formula display so you understand exactly where your number came from. It’s a fast, straightforward way to go from project dimensions to a supplier-ready estimate.

Enter your dimensions, choose your material, and use this gravel calculator to have your estimated order quantity ready before the supplier picks up the phone. The whole process, from first input to estimated tonnage, typically takes just a couple of minutes.