French Drain Calculator

Estimate gravel, pipe, and fabric needed for drainage systems. Calculate trench volume, gravel tons, and pipe length.

📏 Drain Length (feet)

📐 Trench Width (inches)

📏 Trench Depth (inches)

🪣 Drain Pipe Diameter (inches)

🪨 Gravel Type

🧵 Include Filter Fabric?

🔄 Waste Factor (%)

💧 French Drain Materials

0 tons gravel

💧 French drain formula: Gravel volume = (Length × Width × Gravel Depth) ÷ 27 for cubic yards. Gravel weight: ~1.4 tons per cubic yard. Pipe length = trench length.

💡 Pro tip: Use 3/4″ washed gravel for best drainage. Wrap pipe with filter fabric or use sock pipe to prevent clogging. Slope drain 1-2% (1-2 ft per 100 ft) for proper water flow.