How this calculator works
Rectangle, disk, trapezoid and triangle areas are multiplied by a uniform depth. Three-side triangle mode rejects sides that cannot meet. The cited clean-stone bulk density is only a starting value; light aggregates, soil and solid rock need their own measured densities.
Formula
A = L x W, pi x D^2 / 4, b x h / 2, or (front + back) x h / 2; Vnet = A x depth; Vorder = Vnet x (1 + waste); mass = Vorder x density; cost = tonnes x rate or Vorder x rate, plus fixed charges.
Worked example
A 3-4-5 m triangular bed has 6 m2 area. At 0.1 m deep and 1800 kg/m3 it needs 1080 kg, or 1188 kg with 10% extra.
Advertisement
Frequently asked questions
What if I only know a tonnage?
Choose known net mass. The volume is mass divided by bulk density; waste is then applied to that net requirement.
Can I calculate a triangle from three sides?
Yes. Enter all three sides in three-side triangle mode. The two shorter sides must add to more than the longest.
Does density include voids?
Bulk density does. Particle or true density does not; use bulk density when filling a bed.