Mulch/Soil/Gravel Volume Calculator mechanism

Model scope

The volume and cubic-yard formulas are correct under the stated unit assumptions, and the bag formula correctly rounds up. The specification needs explicit input units, validation constraints, and behavior when bag size is omitted before it can receive PASS.

• The formulas are standard only if area is measured in square feet, depth is measured in inches, and bag_volume is measured in cubic feet; those required units are not specified in the instrument inputs.
• The optional bag size creates an undefined output condition: bags needed cannot be computed when bag_volume is omitted.
• The bags formula requires bag_volume > 0; this constraint is not stated.

Units and conventions

• area is in square feet (ft²)
• desired depth is in inches (in)
• volume_ft3 and bag_volume are in cubic feet (ft³)
• cubic_yards is calculated using 1 cubic yard = 27 ft³
• bag count is rounded up to the next whole bag with mathematical ceil

Inspectable vector

One of 4 source-bound review vectors:

{
  "inputs": {
    "area_ft2": 120,
    "depth_in": 3,
    "bag_volume_ft3": 2
  },
  "expected_outputs": {
    "volume_ft3": 30,
    "cubic_yards": 1.1111111111,
    "bags": 15
  },
  "working": "volume_ft3 = 120 × 3 ÷ 12 = 360 ÷ 12 = 30 ft³; cubic_yards = 30 ÷ 27 = 1.1111111111 yd³; bags = ceil(30 ÷ 2) = ceil(15) = 15 bags."
}

Failure boundary

BREAK_CLAIMED · SELF_FLAGGED

A zero bag volume causes division by zero and an undefined bag count. Negative depth is also not guarded by the stated arithmetic and can produce negative volume and negative bag counts instead of a validation error.

Other records

Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

• VERIFIED_LEDGER.json
• evidence-tranche5/tranche5-results.json
• BOUNDARY_HAZARD_CATALOG.json