French Drain Calculator
French Drain Materials
Calculate materials needed for a French drain installation
French Drain Cost Estimate
Estimate the total cost of a French drain project
Formula
Gravel = (Length × Width × Depth) / 27 cu yd | Fabric = (Width + 2×Depth + 1') × Length | Slope = 1/8" per foot minimum
Frequently Asked Questions
How deep should a French drain be?
Exterior/yard drains: 12-24 inches deep. Foundation perimeter drains: as deep as the footing (typically 24-36 inches). Interior basement drains: cut into the slab edge, typically 12-18 inches below the slab. Always slope at least 1% (1/8" per foot) toward the outlet.
What gravel is best for a French drain?
Use washed crushed stone #57 (3/4"-1") or #2 (2.5"-4") stone. Never use round pea gravel (it shifts and compacts). Never use limestone (it can cement together). River rock works but is more expensive. The gravel must be clean and washed to prevent fine sediment from clogging the pipe.
You may also need
~
Gravel Calculator
Free gravel calculator. Calculate how much gravel, crushed stone, or mulch you need in tons and cubic yards for your landscaping project.
Everyday~
Concrete Calculator
Free concrete calculator. Calculate how many bags or cubic yards of concrete you need for slabs, footings, columns, and stairs.
Everyday~
Foundation Calculator
Free foundation calculator. Calculate concrete needed for slab foundations, crawl space walls, and basement foundations with footing estimates.
Everyday