French Drain Gravel & Pipe Material Estimator
Size a French drain from real trench geometry — length, width, depth and runs — then get the gravel (cubic yards and tons), perforated pipe, and filter fabric, with U.S. pricing and a downloadable PDF.
Gravel weight, pipe sizes and fabric widths vary by supplier — confirm local specs and delivery minimums. Prices use 2024-2025 U.S. figures. For planning purposes only.
| Trench Size | Gravel (cu yd) | Gravel (tons) | Est. Cost |
|---|
For your 50 ft of trench, 1 run(s). Highlighted row is closest to your width × depth. Est. cost includes gravel, pipe and fabric.
How to use the French drain estimator
Four quick steps turn your trench size into a full material order — gravel in cubic yards and tons, perforated pipe, and filter fabric — with the pipe displacement handled, your gravel and waste dialed in, a size comparison, and a downloadable PDF.
Enter the trench
Length, width, and depth, plus how many runs you’re digging — the trench volume fills in automatically.
Pick the pipe
Choose a pipe diameter or go gravel-only, and set the pipe type — it displaces a little gravel.
Set gravel, fabric & waste
Pick the gravel and density, choose a fabric wrap, set the waste %, and enter your prices.
Read results & save a PDF
Get gravel, pipe, fabric, a full cost breakdown, a trench-size comparison, and a material list.
How the gravel estimate is calculated
It starts from the trench volume, subtracts the space the pipe takes up, then adds waste for settling — and converts to cubic yards and tons. Pipe and fabric follow from the trench length. Here is the exact math.
Worked example — a 50 ft trench, 12″ wide × 18″ deep, 4″ pipe, +10%
Trench volume: (12÷12) × (18÷12) × 50 = 75 cu ft
Pipe displacement: π × (2÷12)² × 50 ≈ 4.4 cu ft
Gravel: (75 − 4.4) × 1.10 ≈ 77.7 cu ft
Cubic yards: 77.7 ÷ 27 ≈ 2.9 cu yd
Tons: 2.9 × 1.35 ≈ 3.9 tons
≈ 2.9 cu yd (about 3.9 tons) of gravel, plus 50 ft of pipe and roughly 250 sq ft of wrap fabric.
French drain estimating charts
Handy lookups for the questions people ask most — gravel by trench size, gravel and pipe by run length, gravel density, and typical U.S. costs. Figures use a 4-inch pipe, a full fabric wrap, and +10% waste, so always confirm your own trench and stone.
| Trench size (W × D) | Gravel (cu yd) | Gravel (tons) | Notes |
|---|---|---|---|
| 6 × 12″ | ~0.8 | ~1.1 | Shallow surface drain |
| 6 × 18″ | ~1.4 | ~1.8 | Light yard drain |
| 8 × 18″ | ~1.9 | ~2.5 | Standard yard drain |
| 10 × 18″ | ~2.4 | ~3.2 | Wide yard drain |
| 12 × 18″ | ~2.9 | ~3.9 | Wide / heavy flow |
| 12 × 24″ | ~3.9 | ~5.3 | Footing / foundation drain |
Gravel volume = trench volume minus the pipe, times waste, divided by 27. Wider or deeper trenches hold more stone — size the trench for the water you’re moving, not just the pipe.
| Trench length | Gravel (cu yd) | Gravel (tons) | Pipe (ft) | Fabric (sf) |
|---|---|---|---|---|
| 25 ft | ~1.4 | ~1.9 | 25 | 125 |
| 50 ft | ~2.9 | ~3.9 | 50 | 250 |
| 100 ft | ~5.8 | ~7.8 | 100 | 500 |
| 150 ft | ~8.6 | ~11.7 | 150 | 750 |
Pipe length equals the total trench length; a full wrap needs about 5 sq ft of fabric per foot of a 12 × 18″ trench. Add runs by multiplying — two 50 ft runs equal one 100 ft row.
| Gravel type | Density (ton/cu yd) | Tons for 3 cu yd | Best use |
|---|---|---|---|
| 3/4″ clean crushed stone | ~1.35 | ~4.1 | Best drainage, no fines |
| #57 stone | ~1.40 | ~4.2 | Common, widely available |
| 3/8″ pea gravel | ~1.50 | ~4.5 | Rounded, easy to place |
| 1″ river rock | ~1.30 | ~3.9 | Decorative top course |
Tons = cubic yards × density. Suppliers quote by the ton or the cubic yard, so having both numbers makes ordering and price comparisons easier.
| Line item | Typical U.S. range | What moves it |
|---|---|---|
| Drainage gravel | $30–$65 / ton | Stone type, region, delivery |
| 4″ perforated pipe | $0.60–$1.50 / ft | Corrugated coil vs. stick |
| Perforated PVC (SDR-35) | $1.50–$4 / ft | Rigid, heavier duty |
| Nonwoven filter fabric | $0.25–$0.60 / sq ft | Weight and grade |
| Installed French drain | $10–$35+ / linear ft | Depth, access, labor |
2024–2025 U.S. ballparks. Material is gravel, pipe, and fabric; installed cost adds labor and equipment and depends on depth and access. Your local prices will vary.
W × D × length
gravel
outlet ~1%
The gravel comes from three things: the trench size, the pipe sitting inside it, and the waste you add for settling.
- Trench size — width × depth × length × runs sets the raw volume of stone.
- Pipe displacement — the pipe takes up space, trimming the gravel a little.
- Slope & fabric — a ~1% fall to the outlet and filter fabric keep it draining for years.
Everything the estimator works out
One set of trench dimensions gives you a complete material order — the gravel, the pipe, the fabric, the cost, and a size comparison.
Key figures every French drain depends on
Built for any drainage project
From a soggy backyard to a foundation footing drain, the same estimator scales to the trench size, the pipe, and the number of runs.
Fixing a soggy lawn or a downspout that pools, and wants the right gravel, pipe, and fabric without a second trip.
- Measure trench length, width & depth
- Pick a 4″ perforated pipe
- Order a bit extra for settling
Quoting drainage work and needs gravel tons, pipe, fabric, and cost in one place to bid the job fast.
- Set runs and waste for the site
- Enter local gravel and pipe prices
- Save the PDF material list for the quote
Running a perimeter footing drain around a foundation and comparing trench sizes on gravel and total cost.
- Set the deep trench dimensions
- Compare sizes on gravel volume
- Total gravel, pipe & fabric for the run
7 tips for an accurate French drain order
Small habits keep your count right and your drain working, whether you’re digging it yourself or buying for a crew.
French drain estimator FAQ
The gravel, pipe, fabric, depth, and U.S. cost questions people ask most before digging a French drain.
Find the trench volume — width times depth times length — then subtract the space the pipe takes up and add a little waste for settling. A common 12-inch-wide, 18-inch-deep trench holds about 1.5 cubic feet of stone per foot of length.
A 50 ft run of that size needs roughly 2.9 cubic yards (about 3.9 tons) of 3/4-inch drainage gravel, plus the pipe and fabric. Wider or deeper trenches need proportionally more.
Drainage gravel weighs about 1.3 to 1.5 tons per cubic yard, so most people use roughly 1.4 tons per yard as a working figure. 3/4-inch clean stone is near the low end, while denser pea gravel sits higher.
To convert, multiply your cubic yards by the density — 3 cu yd × 1.35 ≈ 4 tons. Suppliers sell gravel by weight or by volume, so knowing both helps you order and compare prices.
Use 3/4-inch clean, washed crushed stone with no fines — the open spaces between the stones are what carry the water. #57 stone is a widely available option that works well.
Avoid stone dust, crusher run, or gravel with a lot of sand, because the fines pack together and clog the drain. Rounded pea gravel drains too, but it can shift more than angular crushed stone.
A typical yard French drain is about 6 to 12 inches wide and 18 to 24 inches deep, which leaves room for a few inches of gravel under and over the pipe. Surface drains can be shallower and foundation drains are deeper.
For a footing or foundation drain, dig down to the base of the footing so the drain sits at the level you want to keep dry. Deeper and wider trenches need more gravel, so size the trench for the job, not just the pipe.
In most soils, yes — wrapping the gravel in nonwoven filter (geotextile) fabric keeps soil silt from washing into the stone and clogging the drain over time. It’s cheap insurance for a drain you’d rather not dig up again.
Line the trench, add the gravel and pipe, then fold the fabric over the top like a burrito before backfilling. In very clean, sandy soils some installers skip it, but wrapping is the safer default.
A 4-inch perforated pipe is the standard for most residential French drains and handles typical yard and downspout flows. Use 3-inch for light-duty runs and 6-inch for large areas or heavy water.
Corrugated HDPE pipe is flexible and inexpensive, while perforated PVC (SDR-35) is rigid and better where you want a cleaner slope or a long life. Lay perforated pipe with the holes facing down so water enters at the bottom.
Materials for a DIY French drain often run about $10 to $25 per linear foot — gravel, perforated pipe, and filter fabric — depending on trench size and local stone prices. A 50 ft run is commonly a few hundred dollars in materials.
Hiring it out adds labor and equipment, and installed French drains commonly run $10 to $35 or more per linear foot, higher for deep foundation drains or hard digging. Get local quotes, since gravel and labor vary by region.
Aim for about a 1% slope — roughly 1/8 inch of drop per foot — so water always flows toward the outlet and doesn’t sit in the trench. Over 50 feet that’s about 6 inches of fall.
More slope drains faster but isn’t required; the key is a consistent, continuous fall with no low spots. Check the trench bottom with a level or a string line as you dig so the pipe runs downhill the whole way.
General Estimating Notice: This calculator estimates gravel, pipe, filter fabric, and cost from your trench dimensions, pipe size, gravel density, fabric mode, waste, and the prices you enter, using typical 2024–2025 U.S. figures. Actual quantities vary with real gravel weight, compaction, over-dig, pipe size, and site conditions, and gravel is sold by weight or volume depending on the supplier. Always confirm local specs, gravel density, and delivery minimums, and add appropriate waste before ordering. For planning purposes only.