Gravel Calculator — Free Online Gravel Estimator

How to Use the Gravel Calculator

1. Enter the area to cover: Measure the total area in square feet where you plan to spread gravel. For rectangular areas like driveways, multiply length by width. For irregular shapes, divide the area into rectangles and add the square footage of each section. For circular areas like fire pits or tree surrounds, use the formula: area = pi x radius squared. Enter the combined total of all areas.
2. Set the gravel depth: Input the desired depth of the gravel layer in inches. For driveways and parking areas, use 4 to 6 inches for adequate structural support and vehicle weight distribution. For walkways, 2 to 3 inches provides stable footing. For decorative landscaping applications, 1 to 2 inches creates an attractive ground cover. Deeper layers require more material but provide longer-lasting coverage.
3. Enter gravel density: Input the density of your chosen gravel type in pounds per cubic foot. The default of 100 lbs/ft³ works for most crushed stone and standard gravel. Lighter decorative gravels like lava rock may weigh 50 to 70 lbs/ft³, while dense river rock can weigh 100 to 120 lbs/ft³. Check with your supplier for the specific density of your gravel type for the most accurate tonnage calculation.
4. Enter the price per ton: Input the current price per ton from your local landscape supply yard. Crushed stone bases typically cost $20 to $40 per ton, pea gravel costs $30 to $60, and decorative stone costs $50 to $150 per ton. Delivery fees are usually separate and range from $50 to $200 depending on distance and quantity ordered.

The calculator instantly displays the total weight in tons, volume in cubic yards and cubic feet, coverage area, and estimated material cost. All values update in real time as you adjust any input.

Gravel Calculation Formula

Variables Explained

• Area: The total ground surface to be covered with gravel, measured in square feet. Accurate area measurement is the foundation of a correct estimate. For complex shapes, breaking the area into simple rectangles and summing them yields the best results.
• Depth: The thickness of the gravel layer in inches, converted to feet by dividing by 12. Depth directly affects volume, weight, and cost. Doubling the depth doubles all material requirements.
• Density: The weight of the gravel per cubic foot, which varies by type. Crushed limestone averages 95 to 105 lbs/ft³, pea gravel 90 to 100 lbs/ft³, and river rock 100 to 120 lbs/ft³. Using the correct density ensures accurate tonnage for ordering.
• Tons Conversion: Weight in pounds divided by 2,000 gives the result in short tons, which is the standard ordering unit for gravel from landscape supply companies and quarries in the United States.

Step-by-Step Example

Suppose you are building a 12 x 30 foot gravel driveway at 4 inches deep using crushed limestone at 100 lbs/ft³ and $45 per ton:

1. Calculate area: 12 x 30 = 360 sq ft
2. Calculate cubic feet: 360 x (4/12) = 120 ft³
3. Convert to cubic yards: 120 / 27 = 4.44 yd³
4. Calculate weight: 120 x 100 = 12,000 lbs = 6.0 tons
5. Estimate cost: 6.0 x $45 = $270

This gravel driveway requires 6 tons (4.44 cubic yards) of crushed limestone at a material cost of $270. Most suppliers require a minimum order of 1 to 3 tons, so this quantity qualifies for delivery without a short-load surcharge.

Practical Examples

Example 1: Mark's Rural Driveway

Mark needs to gravel his 14 x 80 foot rural driveway at 6 inches deep using crusher run gravel at 100 lbs/ft³ and $30 per ton:

• Area: 14 x 80 = 1,120 sq ft
• Cubic feet: 1,120 x 0.5 = 560 ft³
• Cubic yards: 560 / 27 = 20.74 yd³
• Tons: (560 x 100) / 2,000 = 28.0 tons
• Cost: 28.0 x $30 = $840

Mark orders 30 tons of crusher run to account for slight variations in depth across the long driveway. The angular crusher run compacts well under vehicle traffic, creating a stable driving surface. He schedules a dump truck delivery and uses a neighbor's tractor to spread and grade the material.

Example 2: Elena's Garden Pathway

Elena is creating a 3-foot wide, 40-foot long garden pathway using pea gravel at 2 inches deep. Pea gravel density is 95 lbs/ft³ and costs $55 per ton:

• Area: 3 x 40 = 120 sq ft
• Cubic feet: 120 x (2/12) = 20 ft³
• Cubic yards: 20 / 27 = 0.74 yd³
• Tons: (20 x 95) / 2,000 = 0.95 tons
• Cost: 0.95 x $55 = $52.25

Elena orders 1 ton of pea gravel at $55 plus a $75 delivery fee. She installs landscape fabric first and sets steel edging along both sides to keep the round pea gravel from migrating into her flower beds. The smooth texture makes the path comfortable to walk on barefoot.

Example 3: Brian's Parking Pad

Brian is adding a 20 x 20 foot gravel parking pad next to his garage at 5 inches deep. He uses number 57 crushed stone at 100 lbs/ft³ and $40 per ton:

• Area: 20 x 20 = 400 sq ft
• Cubic feet: 400 x (5/12) = 166.7 ft³
• Cubic yards: 166.7 / 27 = 6.17 yd³
• Tons: (166.7 x 100) / 2,000 = 8.33 tons
• Cost: 8.33 x $40 = $333.20

Brian orders 9 tons to provide a small buffer. He excavates 6 inches of topsoil, installs a geotextile fabric, and places the gravel in two lifts, compacting each lift with a plate compactor. The resulting pad provides a solid parking surface that drains well during heavy rain.

Gravel Reference Table

Table assumes gravel density of 100 lbs/ft³. Actual tonnage varies by gravel type. Delivery fees not included in cost estimates.

Tips and Complete Guide

Selecting the Right Gravel for Your Project

Different gravel types serve different purposes, and selecting the right one is critical for project success. For driveways and parking areas, use angular crushed stone like crusher run (a blend of sizes from dust to 1.5 inches) that compacts into a solid, stable surface. For walkways, pea gravel (3/8 to 3/4 inch rounded stones) provides comfortable footing and an attractive appearance. For drainage applications like French drains and behind retaining walls, use clean-washed number 57 stone (3/4 to 1 inch) that allows water to flow freely without clogging. For decorative landscaping, options include white marble chips, Mexican beach pebbles, and polished river rock. Always consider the gravel's tendency to migrate: angular stones stay in place better than round ones.

Preparing the Ground for Gravel Installation

Proper ground preparation ensures your gravel surface lasts for years without issues. Start by removing all vegetation, roots, and topsoil from the area. Grade the subgrade to slope away from buildings at a minimum of 1/4 inch per foot for drainage. Compact the exposed subgrade with a plate compactor or roller. Install a woven geotextile fabric over the compacted soil to prevent gravel from mixing with the soil below and to inhibit weed growth. For driveways, consider installing a stabilization grid (geocell) over the fabric before adding gravel. This plastic grid system locks gravel in place and distributes vehicle weight, reducing ruts and displacement. Set edging along all borders to contain the gravel within the designated area.

Understanding Gravel Sizes and Numbering

Gravel is classified by size using a numbering system. Number 1 stone is the largest at 2 to 4 inches, used for drainage and erosion control. Number 3 stone (1 to 2 inches) is used for the base layer of driveways. Number 57 stone (3/4 to 1 inch) is the most versatile, used for driveways, drainage, and construction bases. Number 8 stone (3/8 to 1/2 inch) works for walkways and as a top dressing over larger base stone. Number 10 stone (stone dust) is used for leveling pavers and filling joints. Crusher run, also called dense grade aggregate, is a blend from dust to 1.5 inches that compacts into an extremely solid surface. Understanding these sizes helps you order the right material and communicate clearly with your supplier.

Common Mistakes to Avoid

• Not accounting for compaction: Loose gravel compacts by 20% to 30% when driven over or tamped. Order 20% to 30% more than the calculated volume if you need a specific finished depth. A 4-inch loose layer settles to about 3 inches after compaction.
• Skipping the geotextile fabric: Without landscape fabric or geotextile, gravel sinks into the soil over time, requiring frequent top-offs that cost more than the fabric would have. This is especially problematic in clay soils that become soft when wet.
• Using the wrong size for driveways: Pea gravel and other round stones shift under vehicle tires, creating ruts and an unstable surface. Always use angular crushed stone or crusher run for vehicle traffic areas. Reserve round stone for decorative and pedestrian applications.
• Ignoring drainage planning: Gravel is permeable, but the subgrade beneath it may not be. If water pools beneath the gravel, it can create soft spots and washouts. Ensure the subgrade slopes properly and consider installing a French drain along the low side of the gravel area.
• Ordering by volume when suppliers sell by weight: Most gravel suppliers sell by the ton, not by the cubic yard. Knowing the density of your gravel type is essential for converting your calculated volume into the tonnage you need to order. Using the wrong density leads to ordering too much or too little material.

Frequently Asked Questions