Figuring Gravel: How to Calculate Yards, Tons and Bags for Any Project
Learn how to figure gravel by hand: formulas for rectangles, circles and irregular shapes, plus yard, ton and bag conversions with worked examples.
Figuring gravel sounds harder than it is. Behind every online gravel calculator is the same short chain of steps: find the area, multiply by depth, convert to cubic yards, then convert to tons or bags. Once you understand the chain, you can estimate any project on paper, double-check a calculator, or compare supplier quotes with confidence. This guide walks through each step, covers rectangles, circles, triangles and irregular shapes, and finishes with a full worked project.
In this guide, a ton means a US short ton (2,000 lb), not a metric tonne. The calculator labels imperial output in short tons and metric output in tonnes. Example weights use an assumed density; the tool uses the density of the selected material, so weight estimates can differ.
Key takeaways#
- Cubic yards = length x width x depth (all in feet) / 27.
- Shortcut: cubic yards = square feet x depth in inches / 324.
- One cubic yard of gravel is roughly 1.4 tons, and about 54 bags at 0.5 cubic feet each.
- For circles use 3.14 x radius x radius. For odd shapes, split them into simple shapes and add.
- Add about 10% for settling, and round up to the quantity your supplier sells.
What Does “Figuring Gravel” Actually Mean?#
When people ask how to figure gravel, they usually want to answer one of three questions:
- How much volume do I need? This is cubic yards, the unit most suppliers use for bulk gravel.
- How much will it weigh? This is tons, which matters if your supplier sells by weight or you need to know what a truck will carry.
- How many bags or loads is that? Useful for small jobs, or when you are moving material by wheelbarrow.
All three come from the same volume calculation, so start there.
Step 1: Gather Accurate Measurements#
- Use a tape measure and measure in feet. If you measure in inches, convert to feet before you calculate.
- Sketch the area and label each side. A rough drawing makes it much easier to split an odd shape later.
- Measure the depth you plan to spread, not the depth of the hole. Common planning depths are about 2 to 3 inches for paths and decorative areas and 4 to 6 inches for driveways.
- Measure more than once. If the width changes along a path, take several readings and use the average, or split the path into sections.
Step 2: Figure the Area by Shape#
Rectangles and squares
Area = length x width. A 25 ft by 3 ft path is 75 square feet.
Circles
Area = 3.14 x radius x radius, where the radius is half the diameter. A circular fire pit area 12 ft across has a 6 ft radius, so the area is 3.14 x 6 x 6 = about 113 square feet.
Triangles
Area = one half x base x height. A triangular corner with a 10 ft base and 6 ft height is 0.5 x 10 x 6 = 30 square feet.
Irregular and curved areas
Break the shape into simple pieces, calculate each, and add them together. A capsule-shaped bed (a rectangle with semicircular ends), for example, can be treated as a rectangle with a half circle on each end. Take an 8 ft by 10 ft rectangle plus two half circles with a 4 ft radius: the rectangle is 80 square feet, the two half circles together make one full circle of about 50 square feet, and the total is about 130 square feet. At a depth of 1 foot, that is roughly 4.8 cubic yards.
| Shape | Area formula | Example |
|---|---|---|
| Rectangle | length x width | 25 x 3 = 75 sq ft |
| Circle | 3.14 x radius x radius | 3.14 x 6 x 6 = 113 sq ft |
| Triangle | 0.5 x base x height | 0.5 x 10 x 6 = 30 sq ft |
| Capsule (rectangle + 2 half circles) | rectangle + 3.14 x radius x radius | 80 + 50 = 130 sq ft |
Step 3: Turn Area into Cubic Yards#
Multiply the area by the depth in feet, then divide by 27, because there are 27 cubic feet in a cubic yard.
- Cubic yards = area (sq ft) x depth (ft) / 27
- Depth in feet = depth in inches / 12
The quick shortcut
Combine those two steps and you get a shortcut that is easy to do in your head: cubic yards = square feet x depth in inches / 324. A 200 sq ft area at 4 inches deep is 200 x 4 / 324 = about 2.47 cubic yards.
Coverage per cubic yard
Flip the shortcut around and you can see how far one cubic yard goes at each depth:
| Depth | Square feet covered by 1 cubic yard |
|---|---|
| 2 inches | 162 sq ft |
| 3 inches | 108 sq ft |
| 4 inches | 81 sq ft |
| 6 inches | 54 sq ft |
Step 4: Figure the Weight in Tons#
Multiply cubic yards by the weight of your gravel per cubic yard. Many suppliers quote roughly 2,500 to 3,000 pounds per cubic yard, which is about 1.25 to 1.5 tons, with a common planning figure of about 1.4 tons. Pea gravel tends to be at the lighter end, crushed stone a little heavier, and compactable mixes such as road base heavier still.
- Tons = cubic yards x about 1.4 (confirm the figure with your supplier)
Moisture changes weight, and so does stone size, so treat the result as a planning number. If your supplier sells by the ton, ask them for the exact weight per cubic yard of the product you are buying.
Step 5: Figure Bags and Wheelbarrow Loads#
Bagged gravel is usually sold by volume, with 0.5 cubic feet a common bag size (0.4 cubic feet bags also exist). Since a cubic yard is 27 cubic feet, one cubic yard equals about 54 half-cubic-foot bags.
| Volume | Cubic feet | Bags at 0.5 cu ft |
|---|---|---|
| 0.25 cubic yard | 6.75 | 14 bags |
| 0.5 cubic yard | 13.5 | 27 bags |
| 1 cubic yard | 27 | 54 bags |
| 2 cubic yards | 54 | 108 bags |
Bags make sense for small jobs, roughly half a cubic yard or less, or where a delivery truck cannot reach. Beyond about a cubic yard, bulk delivery is usually far cheaper per cubic foot and saves a lot of lifting.
For wheelbarrow planning, check your barrow’s capacity. A typical homeowner barrow holds about 3 cubic feet of gravel when filled sensibly, which works out to roughly 9 loads per cubic yard. Larger contractor barrows carry more. Delivery trucks vary a lot in capacity, and suppliers quote anything from about 10 tons for a single-axle truck to over 20 tons for larger ones, so ask what applies to your delivery.
Step 6: Add an Allowance and Round Up#
Gravel settles and compacts after it is spread, and some is lost to handling and irregular edges. Adding about 10% is a common planning allowance, and suppliers often suggest more for small orders. Then round up to the nearest quantity your supplier sells, since delivery fees are usually charged per trip and a second delivery is costly.
Full Worked Example: Path Plus Fire Pit Area#
Suppose you are laying a 25 ft by 3 ft pea gravel path at 2 inches deep, ending at a circular fire pit area 12 ft across at 3 inches deep. Use 1.4 tons per cubic yard and a 10% allowance.
| Part | Area | Cubic yards | Tons |
|---|---|---|---|
| Path: 25 x 3 ft, 2 in deep | 75 sq ft | 75 x 2 / 324 = 0.46 | 0.65 |
| Fire pit: 12 ft across, 3 in deep | 113 sq ft | 113.1 x 3 / 324 = 1.05 | 1.47 |
| Total | 188 sq ft | 1.51 | 2.11 |
| With 10% allowance | 1.66 | 2.33 |
In bags, 1.66 cubic yards would be roughly 90 half-cubic-foot bags, so this project is a strong candidate for bulk delivery. You would likely order about 1.75 to 2 cubic yards, or around 2.5 tons, depending on how your supplier sells and delivers.
Planning Gravel with Pavers and Planting#
A gravel project can combine a path, paver edging and planting beds. Calculate each area and material layer separately so the delivery matches the design. A surface layer and its compacted base need separate estimates.
Common Mistakes When Figuring Gravel#
- Forgetting to convert inches to feet. A 4-inch depth is 0.333 ft, not 4.
- Using diameter instead of radius. Halve the diameter before squaring.
- Calculating the whole area at one depth. If depth varies, figure each section separately.
- Skipping the allowance. Exact figures often leave you short once gravel settles.
- Confusing tons and cubic yards. They are different units, so compare quotes in the same unit.
- Ignoring the base layer. New driveways and paths often need a coarser base underneath, which means a second quantity.
Check Your Math with the Calculator#
Doing the math by hand is the best way to understand your order. Once you have your numbers, run them through the Interior Tailor Gravel Calculator to double-check the result in cubic yards and tons. For more on choosing depth and gravel type, read the gravel calculator guide. Related tools include the Cubic Yard Calculator and the Square Footage Calculator for measuring odd shapes.
Frequently Asked Questions About Figuring Gravel#
How do I figure yards of gravel?
Multiply length by width by depth, all in feet, then divide by 27. For a shortcut, multiply square feet by depth in inches and divide by 324.
How do I figure gravel for a circle?
Find the radius (half the diameter), then multiply 3.14 x radius x radius to get the area. Multiply by depth in feet and divide by 27 for cubic yards.
How many square feet does a cubic yard of gravel cover?
About 162 sq ft at 2 inches deep, 108 sq ft at 3 inches, 81 sq ft at 4 inches and 54 sq ft at 6 inches.
How many bags of gravel are in a cubic yard?
About 54 bags if each bag holds 0.5 cubic feet, or about 68 bags if each holds 0.4 cubic feet.
How do I figure gravel in tons?
Multiply your cubic yards by the weight per cubic yard of your gravel. A common planning figure is about 1.4 tons, but confirm with your supplier.
How do I figure gravel for an irregular area?
Split the area into rectangles, circles and triangles, calculate each one, and add the totals. Use the same depth for each piece, or calculate separate depths separately.
How much extra gravel should I order?
About 10% is a common allowance for settling and waste, and more for small orders. Round up to your supplier’s next available quantity.
Is figuring gravel by hand accurate?
It is as accurate as your measurements and assumptions. Moisture, stone size and compaction all affect real-world amounts, so treat any result as an estimate and confirm with your supplier.
Final Thoughts#
Figuring gravel comes down to one reliable routine: measure, find the area, apply depth, convert to yards, tons or bags, then add a sensible allowance. With that routine you can price a path, a patio or a driveway in a few minutes. When you want a quick second opinion, open the Gravel Calculator and compare.
