Calculate silt fence materials for construction sites. Enter perimeter length to find rolls, posts, and staples needed.
Silt fence is the most common sediment control practice on construction sites. It intercepts sheet-flow runoff, allowing water to pass while trapping sediment. Required by the Clean Water Act for virtually all construction sites disturbing soil, silt fence protects downstream waterways.
This calculator estimates the linear feet of silt fence fabric, number of fence posts, and securing materials based on your site perimeter or downslope run length. Standard silt fence rolls are 100 feet long and 36 inches tall. Posts are typically wooden stakes spaced 6 feet apart.
Whether you're managing a construction site, driveway installation, or land clearing operation, this tool ensures you have the right materials for effective sediment control.
Understanding this metric in quantitative terms allows construction professionals to compare design alternatives, evaluate cost-effectiveness, and select the optimal approach for each project. Accurate calculation of this value helps construction professionals plan projects more effectively, reduce material waste, and ensure compliance with building codes and industry standards.
Construction permits require silt fence installation and inspectors check quantities. Under-installing means permit violations and fines. This calculator provides accurate material counts for ordering and compliance documentation. Accurate figures enable contractors to prepare competitive bids with confidence, reducing the risk of underestimating costs or overcommitting on project timelines and deliverables.
Rolls = Linear Feet ÷ 100 Posts = (Linear Feet ÷ Spacing) + 1 Wire Rolls (50 ft) = Linear Feet ÷ 50
Result: 5 rolls / 84 posts
500 LF of silt fence needs 5 rolls (100 ft each). Posts at 6 ft spacing: 500 ÷ 6 + 1 = 84.3, round up to 85 posts. Add extra rolls and posts for corners, repairs, and overlaps.
Place silt fence along the contour (perpendicular to slope) at the base of disturbed areas. The fence should intercept sheet flow and pond sediment-laden water, allowing it to filter through. Return the ends upslope at least 10 feet to prevent runoff from flowing around.
Inspect silt fence within 24 hours of every rainfall of 0.5 inches or more. Check for undercutting, fabric tears, collapsed posts, and sediment accumulation. When sediment reaches 1/3 the fence height, remove it and spread on flat ground.
Installing in concentrated flow paths (use a sediment trap instead). Not trenching the bottom edge. Using too-wide post spacing on steep slopes. Not returning the ends upslope. Not maintaining the fence after storms.
Straw wattles, fiber rolls, silt socks, and compost filter berms are alternatives for specific situations. For concentrated flows, use sediment basins or traps. For paved areas, use inlet protection. Always refer to your state's BMP manual for approved alternatives.
Standard spacing is 6 feet. Use 4-foot spacing on steeper slopes or in high-flow areas. At corners and turns, add extra posts to maintain the fence line. Closer spacing provides better structural support.
Dig a 6-inch trench along the fence line. Place the fabric in the trench with the bottom turned upslope. Backfill and compact. Drive posts 18‒24 inches into the ground on the downslope side. Attach fabric to posts with staples or ties.
Remove silt fence only after all upslope areas are permanently stabilized with vegetation, pavement, or other cover. Trapped sediment behind the fence should be spread and stabilized before removal. This may be months or years after installation.
Silt fence is designed for sheet flow, not concentrated flow. Maximum contributing slope length is 100 feet. For longer slopes, install multiple parallel rows. Never place silt fence across channels, ditches, or concentrated flow paths.
Wire-backed silt fence is stronger and lasts longer. Use it on steeper slopes, high-flow areas, and projects lasting more than 6 months. Standard fabric-only silt fence works for flat to gentle slopes and short-duration projects.
Standard silt fence costs $0.50–$1.50 per linear foot for materials. Wire-backed costs $1.50–$3.00 per LF. Professional installation adds $1–$3 per LF. Posts cost $1–$3 each. A 500 LF job costs $500–$2,000 in materials.