Sources & formulas

Every calculator on LandscapingCalcs rests on established geometry and arithmetic plus stable landscaping conventions. Unlike topics with a time dependency, "verification" here is mathematical: each formula is tested against known values and is therefore correct for good. Here are the technical foundations by area.

Geometry & units

  • Bulk volume: cu yd = area (sq ft) × depth (in) ÷ 324; 27 cubic feet = 1 cubic yard; one cubic yard ≈ 13.5 bags of 2 cu ft.
  • Weight: tons = cubic yards × density (tons per cu yd; labeled per material).
  • Water: gallons = area (sq ft) × inches × 0.623; an acre is 43,560 sq ft.
  • Areas: ring area = π(r_out² − r_in²); plant count = area ÷ spacing² (÷0.866 for triangular).

Lawn & materials

  • Grass seed / lime: lb = area × rate (lb per 1,000 sq ft) ÷ 1,000; labeled rates by grass type.
  • Fertilizer: lb of product = (N rate × area ÷ 1,000) ÷ (%N ÷ 100); %N is the first NPK number.
  • Sod: pallets = ceil(area ×(1+waste) ÷ 450); rolls = ceil(area ×(1+waste) ÷ 10) — labeled coverage.

Hardscaping, fencing & decking (labeled planning typicals)

  • Pavers: count = ceil(area ×(1+waste) ÷ paver face area); base gravel & bedding sand from area × depth.
  • Retaining wall: blocks = ceil(wall face ÷ block face); tall walls need an engineer and a permit.
  • Fence & deck: posts = ceil(length ÷ spacing) + 1; pickets = ceil(length in ÷ (width + gap)); deck boards = ceil(area ×(1+waste) ÷ board coverage); post concrete = hole volume ÷ bag yield.

Cost tools

  • Every cost tool uses the prices you enter ($/cu yd, $/sq ft, $/ft, $/tree, $/acre, $/hour) — no material or service price, labor rate or cost index is stored, so the site needs no maintenance.
  • Cost: total = quantity × your unit price + labor + delivery, ×(1 + contingency).

Coverage, permit rules, local code, plant hardiness and material lead times vary by place and change over time — always confirm the coverage on the product, and get quotes and permits from a licensed, insured landscaper or contractor and your local building department. Tree work is dangerous — hire a licensed, insured arborist.