Tile Spacing & Cost Calculator — free.
Type in acres and a lateral spacing, and get total tile footage and a cost per acre in seconds. Enough to sanity-check a quote, set a budget, or decide whether a field is worth a closer look — before anyone calls a contractor or books a survey.
A planning estimate from acreage and spacing — not a design. Real footage depends on the field shape, outlet and grade. To lay out the graded, sized design, that’s Geo-Surface Pro (a flat membership — unlimited fields, no per-acre fees).
A free tile spacing calculator and drain tile cost calculator for agricultural drainage. Estimate drain tile cost per acre, lateral spacing in feet, and total tile footage for a parallel pattern-tile field. Built by Geo-Surface Pro — the flat-fee membership for surface drainage, tile, and 3D landforming design, all running in your browser, on unlimited fields with no per-acre charges across the US and Canada.
Estimate in seconds
Total footage and cost per acre, before you commit a dollar
Enter acres, set a lateral spacing for the soil, and add a tile or install cost. You get total tile footage and a cost per acre you can hold a real quote up against.
Field & pattern
Tighter soils need closer laterals to move water; well-drained soils can run wider. This sets a starting spacing — override it anytime, and pin down the real one in the full design.
Cost basis
Your estimate
Total estimated cost
$0 per acre
How this estimate is calculated
A simple parallel-pattern model — the back-of-envelope math used to ballpark a tile budget:
- Lateral footage =
(acres × 43,560) ÷ lateral spacing. One run of tile covers a strip equal to the spacing, so closer spacing means more footage. - Main allowance adds a percentage of lateral footage for collector mains (8% default; 12% for heavier networks; 0% for laterals only).
- Total footage = lateral + main allowance.
- Cost = total footage × your installed cost per foot — or, in per-acre mode, acres × your cost per acre.
- Soil class only suggests a spacing; you can override it. Depth is captured for your records and does not change footage in this estimate.
Mainline pipe sizing
The main size these acres need at this grade — before you order pipe
Enter the acres draining to the main and its average grade to the outlet. You get the required diameter for both single-wall and dual-wall (smooth) pipe, across the drainage coefficients used on real jobs.
Acres & grade
How to use it
Required pipe size
Minimum inside diameter, in inches, for each drainage coefficient. Dual-wall runs smaller than single-wall at the same flow because the smooth bore carries more water.
| Drainage coefficient — in / 24 hr | ||||||
|---|---|---|---|---|---|---|
| Pipe | 1/8" | 1/4" | 3/8" | 1/2" | 3/4" | 1" |
| Single wall | 8" | 10" | 12" | 12" | 15" | 18" |
| Dual wall smooth interior | 6" | 8" | 10" | 10" | 12" | 15" |
1/4"–1/2" — the usual pattern-tile range
>24" means the flow is past this quick chart. Split it into more than one main, or size the main stepwise in Geo-Surface Pro, which steps the diameter up along the run as acres accumulate.
Many regions cap the allowable drainage coefficient for licensing — verify your local drainage rules. Educational estimate, not professional advice; the full disclaimer follows below.
Pattern tile
Parallel pattern tile typically runs a drainage coefficient of 1/4"–1/2" for most soils — the shaded columns above.
Targeted tile
Tile aimed at depressional ground that takes surface runoff warrants a higher coefficient — or add the extra contributing acres to the area.
Combined systems
When a system is pattern plus targeted, size the main from the combined contributing area, not the pattern acres alone.
How this pipe size is calculated
The same open-channel method the paid product's sizing engine uses — a full-pipe Manning calculation, one column per drainage coefficient:
- Peak flow for each coefficient:
Q = acres × coefficient × (43,560 ÷ 12 ÷ 3,600 ÷ 24)— the coefficient is the depth of water (in inches) the tile removes in 24 hours. - Diameter comes from Manning's equation solved for a full circular pipe at your grade, using a roughness that reflects the pipe type: single-wall corrugated runs rougher (and steps up its roughness as it gets larger), dual-wall smooth uses a lower value, so it carries the same flow in a smaller pipe.
- Rounding to a real size: the raw diameter is fitted to the nearest manufactured size (3, 4, 6, 8, 10, 12, 15, 18, 24"), rounding down only when it lands just above a size and up otherwise.
- Above 24" the chart shows
>24"— that flow belongs in a split or a stepwise-sized main, not a single quick pick.
This chart sizes one main for a flat contributing area. Geo-Surface Pro sizes every main stepwise from the network you actually draw, stepping the diameter up at each lateral as acres accumulate. See it in the demo.
Read this before you quote it
It's a planning estimate, not a design
This calculator assumes a clean, evenly spaced parallel pattern across a perfect rectangle. Real fields aren't rectangles, and water doesn't run uphill. Treat the number as a ballpark to budget around or sanity-check a quote — not a figure to sign a contract on.
Good enough to
- Set a rough budget before you call anyone
- Sanity-check a contractor's cost per acre
- Decide whether a field is worth a closer look
- Compare two spacings or two cost bases side by side
Not built to
- Order materials or lock a final bid
- Account for the actual field shape or outlet
- Size pipe to grade or set tile depth to fall
- Replace a real layout or an RTK survey
Plan and quote from elevation data — survey and grade with RTK when the job goes ahead. Geo-Surface Pro turns this ballpark into a graded, sized layout over the real field shape, with elevation built in, so there's no survey just to plan. The committed job is then surveyed run-by-run with your machine-control RTK and built however you already work.
Common tile drainage questions
How far apart should drain tile be?
Depends almost entirely on your soil. Tight, poorly drained clay might need laterals every 30–50 ft to keep up; sandy loam can run 80–100+ ft apart and still drain fine. The calculator above gives you a starting spacing by soil class — punch in your acres and see what the footage does at different spacings. Geo-Surface Pro goes a step further and pulls SSURGO and SoilGrids soil data for your actual field, so the suggested spacing, depth, and drainage coefficient are cited to real soil under your ground, not a generic guess.
How much does tile drainage cost per acre?
It varies a lot — by region, tile spacing, depth, and who's installing it. There's no single number worth quoting you here. What actually works: plug your own installed cost (per foot or per acre, whichever you have from a quote) into the calculator above, and it'll turn your spacing and acreage into a real footage count and a total you can hold that quote up against, instead of trusting somebody else's average.
What tile spacing works for clay vs. sandy soil?
Clay and other tight, slow-draining soils move water through the profile slowly, so laterals need to sit closer together — tighter spacing keeps the field from ponding between runs. Sandy or well-drained loam moves water fast enough that you can space laterals wider and still get the field dry in time. Everything in between (silt loam, silty clay loam) lands somewhere in the middle. The soil dropdown above gives you a starting spacing; Geo-Surface Pro pulls SSURGO (US) and SoilGrids data for your actual field boundary and suggests spacing straight from that.
The calculator ballparks it. Pro designs it — on your real field, no per-acre fee.
The calculator gives you a ballpark. Geo-Surface Pro designs the real thing — on your actual field, with your actual outlet and grade. One flat membership covers surface drainage, tile, and 3D landforming: $499/yr launch price, unlimited fields, no per-acre fees, ever. A single ~160-acre landforming design billed by the acre (~$9.90/ac) runs about $1,584 — more than three years of Geo-Surface Pro.
One membership, three jobs: surface drainage · tile design · 3D landforming — all in your browser.
- Design over the real field, not a flat assumption. Spot ponding and flow paths, then lay out surface drainage and tile with auto pipe sizing, stepped mains, a live profile chart, and soil-based spacing suggestions — on your actual boundary, outlet, and grade.
- 3D landforming, one flat price. Pick your outlets, set a max cut, hit Solve — every acre drains to the outlets you chose with no ponding left behind, and fill is borrowed from nearby high ground so most of the field stays untouched. No per-acre design fee, ever.
- A quote you can hand over. Client-ready PDF report plus CAD layout/centerlines (DXF), shapefile and KML. When the job's committed, survey each run with your machine-control RTK and build to the plan.
$499/yr is a launch price — new signups move up to $799/yr on September 1, 2026. Sign up now and your renewal stays locked at $499/yr for as long as you keep your membership, with every future feature included. Backed by a 30-day money-back guarantee.
Plan and quote from elevation data. Survey and grade with RTK when the job goes ahead.
