Calculated result
3.9yd³
Drainage stone order
Formula
LND-FRN-001(L × W × D − pipe cylinder) × (1 + waste) ÷ 27
50 ft
Pipe to buy
250 ft²
Wrap fabric area
95.64 ft³
Net stone volume
Landscaping calculator
French drain
Drainage-stone volume, pipe length and wrap-fabric area from trench length, width, depth and pipe diameter.
Reviewed formula · v1.0.0
Project inputs
Enter field measurements. Imperial lengths take feet and inches. Unit conversion happens before the reviewed formula is applied.
All values can be refined when you edit the estimate. This tool does not replace field verification or local requirements.
Transparent cost view
Planning rates only. Pick a currency — badges, inputs, and totals follow. Material is a rate. Labour is hours × a planning hourly rate. Equipment and delivery are this-job amounts.
Planning defaults are office figures, not a bid. US ready-mix in 2026 often lands around $125–165 per cubic yard delivered; place-and-finish commonly $2–4 per square foot. Replace every rate with a supplier or crew quote before you send the letter.
Indicative FX as of Aug 2026. Planning conversion, not a live bank rate.
Material costUSD 332
Labour (8 h)USD 280
Direct costUSD 722
Overhead + contingencyUSD 72.15
Markup + taxUSD 95.24
Estimated project totalUSD 889
How this calculator works
A transparent french drain takeoff.
Trench volume minus the pipe cylinder, with waste applied to the stone, plus the pipe length and a wrap-fabric area of length × (2 × depth + width).
Worked example. Example: a 50 ft trench, 1 ft wide and 24 in deep, with 4 in pipe and 10% waste rounds to 3.9 yd³ of stone, 50 ft of pipe and 250 ft² of fabric.
- 1. Measure the drain centerline, not the downspout run on the roof.
- 2. Enter excavated width and depth. A 4 in pipe commonly sits in about a 1 ft trench.
- 3. Keep outlets, cleanouts and a catch basin as separate pieces.
Need the broader workflow? Read the landscaping planning guide.
Questions
Questions about french drain
Does this size the drain?
No. It is a material takeoff from the trench you already planned. Slope, fabric type and stone gradation stay with the drainage design.
Sock pipe vs bare pipe plus fabric?
Pipe length is the same. If the pipe is already sleeved, you may not need the wrap-fabric area — leave it off the estimate.
What is the formula ID?
This calculator publishes formula LND-FRN-001, version 1.0.0. The ID stays on the result and on the estimate line.
Is this engineering advice?
No. Construclytic is a planning website, not a registered engineering or contracting firm. Field checks, codes and product data still sit with you.
Does Construclytic fetch live supplier prices?
No. Costs use the rate you enter. Construclytic does not fetch live supplier prices.