How to use this calculator
- Enter Length in ft.
- Enter Width in ft.
- Enter Depth in in.
- Enter Price per ton in $.
- Press Calculate. The highlighted row is your order quantity; the note beneath it translates the number into real-world terms.
Formula & constants
Rip rap places at roughly 100 lb/ft³ void-inclusive. Layer thickness should be 2× the median stone size (D50) — 18 in is typical for 6–9 in stone over filter fabric. Every default in the fields above is editable — when your supplier’s spec sheet lists a different density, coverage rate or price, enter that number instead. The waste and compaction allowances follow common trade practice; see our methodology page for the derivation of each formula and the standards it references.
One ton covers ~13 sq ft at 18 in deep.
Where this fits in the project
Aggregate quantities feed the layers above them: after excavation, base material is placed in compacted lifts before asphalt or concrete goes down. Convert your tonnage to trips with the truckload calculator before scheduling delivery.
How this connects to your project
No quantity stands alone — each material in the chain depends on the ones around it. These are the planning steps that pair with the rip rap calculator:
- Gravel Calculator — Rip rap is much larger stone than standard gravel.
- Crushed Stone Calculator — Rip rap is the largest grade of crushed stone.
- Limestone Calculator — Rip rap is frequently limestone or granite.
- French Drain Calculator — Rip rap is for erosion control, not subsurface drainage.
- Retaining Wall Calculator — Rip rap may be placed at retaining wall base for drainage.
- Excavation Calculator — Rip rap is placed after shoreline or slope excavation.
Frequently asked questions
What size rip rap do I need?
Size to flow velocity: 3–6 in stone for mild swales, 6–12 in for channels, 12–24 in for shoreline wave action.
Is fabric required under rip rap?
Yes — non-woven geotextile stops soil piping through the voids, which is the primary failure mode.
Last verified: — prices reflect current national averages. See our methodology.
Estimates are for planning. Material densities, coverage rates and prices vary by region and supplier — confirm final quantities before ordering, and check local code where structural or electrical work is involved.