CalculatorMulchHow We Calculate
Every calculator on this site runs on the same three steps, in the same order the supply yard does it: area ร depth = volume, volume รท 27 = cubic yards, cubic yards ร density = weight.
The formulas
- Rectangle: length ft ร width ft
- Circle: ฯ ร (diameter รท 2)ยฒ
- Triangle: base ร height รท 2
- Ring around a tree: ฯ ร (outer radiusยฒ โ trunk gapยฒ). A mulch ring is a circle with a hole in it, and the hole is not a detail โ mulch piled against the bark is what kills the tree. If the gap is wider than the ring, the area is zero rather than a negative number.
- Volume: area sq ft ร (depth in รท 12) = cubic feet; รท 27 = cubic yards, because a cubic yard is a 3 ft cube and 3 ร 3 ร 3 = 27.
- Bags: cubic feet รท bag size, always rounded up โ nobody sells half a bag.
- Weight: cubic yards ร the material’s pounds per cubic yard from the table below; tons = pounds รท 2,000.
The density table
These are dry, loose, as-delivered figures โ the single number in the middle is what every calculator on this site uses, the range is the published spread. Organic materials gain 20โ40% of their weight when soaked, which matters for your truck’s payload far more than for your order.
| Material | We calculate with | Published range | Usual bag | Worth knowing |
|---|---|---|---|---|
| Shredded hardwood mulch | 700 lb/ydยณ | 400โ800 lb | 2 cu ft | The default US bagged mulch. Knits together on slopes. |
| Pine bark mulch | 500 lb/ydยณ | 400โ700 lb | 3 cu ft | Sold in 3 cu ft bags. Light, floats in heavy rain. |
| Cypress mulch | 550 lb/ydยณ | 450โ750 lb | 3 cu ft | Also a 3 cu ft bag material. |
| Rubber mulch | 800 lb/ydยณ | 600โ900 lb | 0.75 cu ft | Sold in 0.75 and 1.5 cu ft bags; does not decompose. |
| Engineered wood fiber | 500 lb/ydยณ | 400โ650 lb | 2 cu ft | Playground surfacing tested to ASTM F1292. |
| Screened topsoil | 2200 lb/ydยณ | 2000โ2700 lb | 1.5 cu ft | Wet topsoil runs to the top of the range. |
| Garden soil / raised bed mix | 1600 lb/ydยณ | 1300โ1900 lb | 1.5 cu ft | Blended topsoil and organic matter. |
| Finished compost | 1300 lb/ydยณ | 1000โ1600 lb | 1 cu ft | Settles 10-15 percent after the first watering. |
| Potting mix | 700 lb/ydยณ | 500โ900 lb | 1.5 cu ft | Peat and bark based; the lightest soil product sold. |
| Fill dirt | 2500 lb/ydยณ | 2200โ2900 lb | 1.5 cu ft | Subsoil with no organic matter. Compacts hard. |
| Crushed stone (#57, 3/4 in) | 2700 lb/ydยณ | 2500โ2900 lb | 0.5 cu ft | Angular, locks together, the driveway standard. |
| Pea gravel | 2500 lb/ydยณ | 2400โ2700 lb | 0.5 cu ft | Rounded 3/8 in stone; migrates without edging. |
| River rock (1-3 in) | 2800 lb/ydยณ | 2600โ3000 lb | 0.5 cu ft | Larger stone needs more depth to hide the fabric. |
| Sand (masonry / paver / play) | 2700 lb/ydยณ | 2600โ3000 lb | 0.5 cu ft | Damp sand is heavier than dry by roughly 10 percent. |
| Decomposed granite | 2900 lb/ydยณ | 2700โ3100 lb | 0.5 cu ft | Compacts into a firm path surface. |
Where the figures come from
Densities follow the ranges published by university extension services and the USDA NRCS soil bulk density guidance; playground depths follow the CPSC Public Playground Safety Handbook. Prices are never estimated โ you type your own. Everything runs in your browser: nothing is stored, and nothing is sent anywhere.