Why Getting the Quantity Right Matters
Ordering too little crushed stone means a second delivery, almost always at a higher effective cost per ton once additional delivery charges are factored in. Ordering too much leaves you paying for material you cannot use and finding somewhere to store or dispose of the surplus. A straightforward calculation before contacting a supplier saves both money and inconvenience, and the maths involved is genuinely simple once you understand the steps.
This guide walks through the complete calculation process from raw measurements to a final tonnage figure ready to give to a supplier, with worked examples for a standard two-car driveway and guidance on adjusting the calculation for irregular shapes, multiple layers, and different stone types. For guidance on which grades to specify for each layer, the best crushed stone for driveways and how to choose page covers grade selection in detail. For current pricing to apply against your calculated quantities, the gravel driveway cost guide and the driveway gravel cost per ton guide provide up-to-date regional price ranges.
What You Need Before You Start
The calculation requires three inputs: the dimensions of the driveway, the intended depth of each stone layer, and the weight conversion factor for the stone type you are ordering.
For dimensions, a measuring tape works for shorter driveways and a measuring wheel is more practical for longer ones. Measure length and width in feet. If the driveway varies in width, measure at several points and use the average, or break the area into distinct sections and calculate each one separately.
For layer depths, a standard residential driveway uses three layers. The gravel driveway base requirements guide and recommended base thickness for gravel driveways pages provide depth specifications for different soil types and traffic loads. The standard starting point for average soil and normal residential traffic is four to six inches of #3 subbase, three to four inches of crusher run base, and two to three inches of #57 or #67 surface stone.
For weight conversion, the standard factor for most limestone and granite crushed stone grades is 1.4 tons per cubic yard. Dense trap rock runs approximately 1.5 tons per cubic yard. Recycled crushed concrete is lighter at approximately 1.25 tons per cubic yard. Always confirm the specific weight with your supplier before finalising your order, as the exact figure varies between quarries and stone types.
Step-by-Step Calculation
Step 1: Measure the Driveway
Walk the full length of the driveway and measure it in feet. Measure the width at the widest point and at the narrowest. If the driveway is a consistent width, use that single figure. If it widens at the entrance or varies along its length, break the area into rectangular sections and measure each one separately.
Step 2: Calculate the Area in Square Feet
Multiply the length by the width to get the total square footage. For a driveway with multiple sections, calculate each section separately and add the results together. For a curved or irregular driveway, a practical approach is to measure the full length along the centreline and multiply by the average width.
Example: A straight driveway 20 feet wide and 60 feet long has an area of 1,200 square feet.
Step 3: Determine the Required Depth for Each Layer
Convert each layer depth from inches to feet by dividing by 12.
Common conversions:
| Depth in inches | Depth in feet |
|---|---|
| 2 inches | 0.17 feet |
| 3 inches | 0.25 feet |
| 4 inches | 0.33 feet |
| 5 inches | 0.42 feet |
| 6 inches | 0.50 feet |
Step 4: Calculate Volume in Cubic Feet
Multiply the square footage by the depth in feet for each layer.
Example using 1,200 square feet:
#3 subbase at 5 inches (0.42 feet): 1,200 x 0.42 = 504 cubic feet
Crusher run base at 4 inches (0.33 feet): 1,200 x 0.33 = 396 cubic feet
#57 surface at 3 inches (0.25 feet): 1,200 x 0.25 = 300 cubic feet
Step 5: Convert Cubic Feet to Cubic Yards
Divide each cubic feet figure by 27.
Continuing the example:
#3 subbase: 504 / 27 = 18.7 cubic yards
Crusher run base: 396 / 27 = 14.7 cubic yards
#57 surface: 300 / 27 = 11.1 cubic yards
Step 6: Convert Cubic Yards to Tons
Multiply each cubic yards figure by the weight factor for the stone type. Using the standard 1.4 factor for limestone:
Continuing the example:
#3 subbase: 18.7 x 1.4 = 26.2 tons
Crusher run base: 14.7 x 1.4 = 20.6 tons
#57 surface: 11.1 x 1.4 = 15.5 tons
Raw total across all layers: 62.3 tons
Step 7: Add the Waste and Contingency Factor
Add ten percent to the total to account for uneven spreading depth, edge losses, and minor subgrade variation.
Final order quantity: 62.3 x 1.10 = 68.5 tons, rounded to 70 tons.
This would typically be ordered as three separate deliveries: approximately 29 tons of #3, approximately 23 tons of crusher run, and approximately 17 tons of #57. Confirm minimum load requirements and delivery scheduling with your supplier, as these vary significantly between companies.
Quick Reference: Standard Two-Car Driveway
A two-car driveway is typically 18 to 20 feet wide and 40 to 60 feet long. The table below gives approximate total tonnage requirements for three common driveway lengths at a standard three-layer build using limestone grades.
| Driveway Size | Total Area | Total Depth | Approximate Total Tons |
|---|---|---|---|
| 18 ft x 40 ft | 720 sq ft | 10 inches | 30 to 35 tons |
| 20 ft x 40 ft | 800 sq ft | 10 inches | 33 to 39 tons |
| 20 ft x 60 ft | 1,200 sq ft | 12 inches | 58 to 70 tons |
| 20 ft x 80 ft | 1,600 sq ft | 12 inches | 78 to 92 tons |
These figures include the ten percent contingency and assume the standard 1.4 tons per cubic yard conversion for limestone. Adjust upward by approximately seven percent if using trap rock, and downward by approximately ten percent if using recycled crushed concrete.
Calculating for Irregular Driveway Shapes
Many residential driveways are not simple rectangles. A driveway that curves, widens at the entrance into a turning area, or splits to serve a garage and a separate parking bay needs a slightly different approach.
The most practical method for a curved driveway is to measure the centreline length from the road edge to the garage or parking area end, and then measure the width at five or six evenly spaced points along that centreline. Average the width readings and multiply by the centreline length. This gives a good approximation of the total area for most gentle curves.
For a driveway with a distinct wider section at one end, such as a turning circle or parking bay, measure the narrow lane portion and the wider area separately. Calculate the square footage of each, add them together, and proceed with the depth calculation as normal.
For particularly complex shapes, a conservative approach is to divide the driveway into simple rectangles and triangles, calculate each shape’s area using its own length and width, and sum all the areas before applying the depth conversion.
Checking Your Calculation with Coverage Rates
A useful cross-check is to apply the standard coverage rate for the stone grade you are ordering. For most #57 and #67 crushed stone grades, one ton covers approximately the following areas at different depths:
| Depth | Coverage per ton |
|---|---|
| 2 inches | approximately 100 square feet |
| 3 inches | approximately 65 square feet |
| 4 inches | approximately 50 square feet |
| 6 inches | approximately 33 square feet |
Divide your driveway area by the coverage rate for your intended surface depth to get the approximate tonnage needed for that layer. If this figure broadly matches your volume-based calculation, you can be confident the numbers are in the right range.
For a full reference on stone grades and their typical applications, the crushed stone size chart and practical uses page and the crushed gravel stone sizes chart and grades are useful companions. For an explanation of how suppliers price stone and how ton versus cubic yard pricing affects your total cost, the driveway gravel cost per ton vs cubic yard guide covers this in full. The best crushed stone types for durable driveways page covers how choosing granite or trap rock instead of limestone changes the weight factor and therefore the tonnage estimate.
Frequently Asked Questions
How do I calculate how much crushed stone I need for a driveway?
Measure the driveway length and width in feet and multiply them to get the square footage. Multiply the square footage by the intended layer depth in feet to get cubic feet. Divide by 27 to get cubic yards, then multiply by 1.4 to estimate tons for most crushed stone grades. Repeat for each layer and add the results together. Always add ten percent to the final total to allow for spreading variation and edge losses.
How many tons of crushed stone do I need for a standard driveway?
A standard two-car driveway measuring 20 feet wide by 40 feet long, built to a total depth of ten inches across three layers, requires approximately 25 to 30 tons of crushed stone in total. This breaks down as roughly 12 to 14 tons for the #3 subbase at four to five inches, 8 to 10 tons for the crusher run base at three inches, and 5 to 6 tons for the #57 surface layer at two to three inches. These figures are estimates and actual quantities depend on precise depths, compaction, and subgrade conditions.
How many cubic yards are in a ton of crushed stone?
For most crushed stone grades, one ton occupies approximately 0.7 cubic yards, meaning roughly 1.4 tons fills one cubic yard. This conversion factor varies slightly by stone type: dense trap rock is closer to 1.5 tons per cubic yard, while lighter recycled crushed concrete is closer to 1.25 tons per cubic yard. Always confirm the weight per cubic yard with your specific supplier before finalising your order, as quarry-to-quarry variation does occur.
How much crushed stone do I need per square foot?
At a two-inch depth, one ton of crushed stone covers approximately 100 square feet. At three inches it covers approximately 65 square feet, and at four inches approximately 50 square feet. These figures use the standard 1.4 tons per cubic yard conversion factor. For a full multi-layer driveway, calculate each layer separately using these coverage rates rather than applying a single figure to the total depth, as different layers use different grades.
Should I order crushed stone by the ton or cubic yard?
Most aggregate suppliers price and deliver crushed stone by the ton, so ordering by the ton is generally more straightforward. Cubic yards is a volume measurement and tons is a weight measurement: the same volume of different stone types weighs different amounts, which is why calculating in cubic yards first and then converting to tons using the appropriate weight factor gives the most accurate order quantity. The driveway gravel cost per ton vs cubic yard page on this site explains the relationship between these two units in more detail.
How do I calculate crushed stone for an irregular shaped driveway?
For a curved or irregular driveway, measure the full length along the centreline from end to end and then measure the width at five or six evenly spaced points along that length. Average the width measurements and multiply by the centreline length to get an approximate square footage. For driveways with distinct sections of different widths, such as a narrow lane opening to a wider parking area, measure each section separately, calculate the area of each, and add them together before applying the depth calculation.
Why should I add ten percent to my crushed stone order?
Spreading depth is never perfectly uniform across a real driveway surface. Low spots in the subgrade require slightly more material than the planned depth, and stone is inevitably lost at the edges during spreading and compaction. A ten percent contingency ensures the job can be completed in a single delivery without running short. Running short and needing a second delivery almost always costs more per ton than ordering the correct quantity initially because of fixed delivery charges and potential minimum load requirements.
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