A 100-foot swale lined 2 feet wide at 4 inches deep takes about 2.5 cubic yards — order 3. The math: 100 ft × 2 ft = 200 sq ft, times 4 inches, divided by 324. Wider or deeper channels scale the same way, and angular ¾-inch granite is the workhorse — it locks in place while water moves through it.
Swale sizing for a 100-ft run
| Lining | Stone needed |
|---|---|
| 2 ft wide × 4" deep | 2.5 → order 3 yards |
| 3 ft wide × 4" deep | 3.7 → order 4 yards |
| 3 ft wide × 6" deep | 5.6 → order 6 yards (one full load) |
Step up to larger stone where flow concentrates, like a downspout outlet or culvert mouth. Order Gray Granite ¾" and check your dimensions with the material calculator.
