Every estimate uses your measurements and your prices. No live retailer pricing or undisclosed price averages are used.
Area and volume
Rectangle area = length × width. Circle area = π × (diameter ÷ 2)². For each area, multiply its area in square feet by depth in feet. Add those volumes, then multiply by (1 + extra percentage ÷ 100).
Bags = round up (total cubic feet ÷ bag volume)
US dimensions use feet for lengths and inches for depth. Metric dimensions use meters for lengths and centimeters for depth. Conversion uses exactly 0.3048 meters per foot and 2.54 centimeters per inch. Switching units preserves the underlying measurements.
Purchases and prices
Bulk orders are rounded up to your supplier’s increment after applying the minimum order. When gravel is priced by weight, cubic yards × supplier density gives US short tons (2,000 lb each). The initial 1.4 tons per cubic yard is an editable planning assumption, not a verified density for your material. Confirm density, moisture and compaction with your supplier.
Bag cost = whole bags × price per bag. Bulk cost = rounded bulk quantity × price per bulk unit. For each option, the selected tax percentage applies to materials and, when enabled, delivery. Enter the supplier’s total tax for bags or bulk to override the percentage for that quote. Tax treatment varies by jurisdiction; confirm the final supplier quote.
The cheaper option is determined by total price, including any minimum order and delivery. The break-even delivery figure shows the highest bulk delivery charge at which bulk would cost no more than bags under your current inputs.
Depth and allowances
Initial depths (mulch 3 inches, gravel 2 inches, topsoil 4 inches) and 10% extra are starting examples. Gravel depth depends on use and any base layers; topsoil depth depends on the planting plan. These are quantity estimates, not construction specifications.
Sources
- University of Minnesota Extension: planting and mulching — guidance includes 2–3 inches of mulch around new plantings and keeping mulch clear of the trunk.
- NIST: US customary and metric conversions — unit reference, including the 2,000 lb US short ton.
Reviewed October 29, 2026. Check the package label and supplier requirements before purchasing. Soil settling, stone density, compaction, moisture, and the shape of your site can change real quantities.