Pea Gravel Calculator
Estimate pea gravel volume, weight, order allowance, bag count, and project material cost.
Project inputs
Live estimate
Base material and allowance
Quantity breakdown
| Measure | Base quantity | With allowance | Unit |
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How to use the pea gravel calculator
What this calculator does
This calculator estimates the amount of pea gravel needed for a rectangular project area. It turns length, width, and finished depth into surface area and volume, uses a bulk-density assumption to estimate weight, adds an optional ordering allowance, converts the result into whole retail bags, and estimates material cost. It is useful for early purchasing and budgeting, but it does not design drainage, determine structural base requirements, account for excavation spoil, or replace site-specific advice.
When to use it
Use it when planning a garden path or patio, topping a decorative landscape bed, estimating loose aggregate around stepping stones, or preparing a preliminary quantity for a drainage trench. For permeable projects, review the U.S. EPA's guidance on permeable pavement and stormwater benefits before treating pea gravel as a complete drainage system.
How to calculate
- The calculator opens with a complete 10 ft × 15 ft × 2 in demonstration, so the results and example Excel workbook are ready immediately.
- Replace Length, Width, and Gravel depth with your measurements. Use decimal points, not decimal commas.
- Confirm Bulk density from the supplier when possible, set an Extra allowance, enter the Price per ton, and choose the retail Bag volume.
- Read the recommended order, secondary quantities, chart, and breakdown table. Select Download Excel to save the current validated model.
- Reset clears the demonstration and all computed data. Download Excel is then disabled until a complete valid state is entered again.
Input guide
Length and Width are required positive dimensions in feet; for example, 10 and 15. Increasing either increases area, volume, weight, bags, and cost proportionally. Do not enter inches in these fields. Gravel depth is a required positive layer thickness in inches; 2 in is common for a light decorative path, while project requirements vary. Enter the finished layer depth, not the depth of the entire excavation. Bulk density is required in pounds per cubic foot; the 96 lb/ft³ demonstration value is a planning assumption, and a wet or differently graded product may differ. Extra allowance is required from 0% to 100%; 10% adds material for minor unevenness, handling, and settlement, but it should not conceal poor measurements. Price per ton is a required nonnegative U.S. dollar amount; it excludes tax and delivery. Bag volume chooses 0.4, 0.5, or 1 cubic foot and changes only the whole-bag estimate.
Output guide
Recommended order is the base weight plus allowance, in U.S. short tons. Surface area is the exact rectangular area in square feet. Volume needed is the geometric volume in cubic yards before allowance. Base weight applies the entered bulk density to that volume. Estimated cost multiplies the recommended order by price per ton and is an estimate, not a quote. Approximate bags rounds the allowance-adjusted volume up to a whole bag. Coverage rate shows how many square feet one ordered ton covers at the entered depth and density. The summary pills repeat area, volume, base weight, and cost. The chart separates base weight from the additional allowance; the table shows volume and weight before and after allowance.
Worked example
The startup project is 10 ft long, 15 ft wide, and 2 in deep. Area is 10 × 15 = 150 sq ft. Converting 2 in to feet gives 2 ÷ 12 = 0.1667 ft, so volume is 150 × 0.1667 = 25.00 ft³, or 25 ÷ 27 = 0.9259 yd³. At 96 lb/ft³, base weight is 2,400 lb, or 1.20 short tons. A 10% allowance adds 0.12 ton, producing a recommended order of 1.32 tons. At $150 per ton, estimated material cost is $198.00. The adjusted volume is 27.50 ft³, requiring 55 half-cubic-foot bags.
Formula and planning assumptions
Volume (ft³) = length (ft) × width (ft) × depth (in) ÷ 12
Weight is volume multiplied by loose bulk density. Because density depends on particle grading, moisture, and void space, supplier data is more reliable than a universal constant. The U.S. Geological Survey describes construction sand and gravel as a major construction raw material, while its construction aggregates overview explains how natural aggregates are recovered, processed, and used.
Practical purchasing notes
Measure irregular spaces as several rectangles and add the results, or subtract unfilled rectangles from a larger bounding rectangle. Keep the same finished depth across each piece unless the design changes. Bulk deliveries are normally sold by weight or volume and may be subject to minimum loads; bagged material is convenient for small sites but often costs more per unit. Rounded pea gravel can move under traffic, so edging and a suitable base may be important. For vehicle or structural applications, use a qualified local specification rather than selecting depth from appearance alone.