This calculator vs. a flat price per foot
French-drain contractors are shopped by a flat price per foot. That rate cannot see the job — depth, pipe size, soil, the outlet, catch basins, and a driveway crossing do not scale with linear footage, and an 80-foot run can take five times the labor of a 40-foot run.
What a flat price per foot is
A price per foot is the fastest number to quote over the phone: pace off the run, multiply by a rate, read back a total. It is also the unit homeowners already compare between competing bids.
The rate behind it was learned from a specific job — a given depth, soil, and outlet — and then reused for the next linear footage that calls in, whether or not that next job shares any of those.
What this calculator is
This page keeps no account and sends nothing to a server. You enter linear feet, trench depth, pipe size, soil, the outlet (daylight, drywell, or storm tie-in), catch basins, downspout ties, a driveway crossing, and extra solid pipe to the outlet, plus your own wage, payroll burden, material rates, travel, overhead, and target margin. It prices the trench, the outlet, and every extra as their own hours and cost lines — for this job, not a rate carried over from the last one.
| What a flat per-foot rate does | What this calculator does instead |
|---|---|
| Charges the same rate for an 18-inch trench in loam and a 36-to-48-inch trench in clay or rock, even though depth and soil are most of the labor. | Prices trench hours from depth and a soil hour factor, so a deep clay run costs more without anyone eyeballing a surcharge. |
| Has no line for the outlet — daylighting to grade, a drywell pit, and a permitted storm tie-in get the same rate. | Prices outlet hours and kit cost separately by outlet type. |
| Has no line for catch basins, downspout ties, extra solid pipe, or a driveway crossing at all. | Prices each of those as its own hours and material, on top of linear footage. |
| Bills pipe size inside the same blended per-foot number, if at all. | Prices a 6-inch pipe's extra material cost and hour premium separately from a 4-inch run. |
| Gives the crew a number to quote, not a number to check a quote against. | Reports the price per foot and the walk-away price alongside the total, so a shopped rate can be scored against real cost before you match it. |
Same trade, two different jobs
Using this calculator's own shipped cost inputs — $42 hourly wage, 30% burden, $95 travel and equipment, 15% overhead, 30% target margin:
A 40-foot shallow daylight trench in dirt, with a lawn restore, takes 9.3 crew-hours and prices at $1,862.64 for the job — $46.57 per foot.
An 80-foot deep drywell run in clay — twice the footage — with two catch basins, three downspout ties, and a 15-foot driveway crossing takes 45.3 crew-hours, costs $6,177.40 to run before a dollar of profit, and this calculator prices it at $8,824.85 — $110.31 per foot. Quoting the deep job at the shallow job's learned rate of $46.57 per foot gives $3,725.28 for eighty feet, which is $2,452.12 below the deep job's own break-even cost — before counting the $5,099.58 it falls short of this calculator's own price at a 30% target margin. Twice the footage, roughly five times the labor, and a rate learned on the shallow job loses money the moment the trencher hits clay.
Common questions
Why does a flat price per foot get a French-drain bid wrong?
Because linear footage only measures how long the trench is, not what it takes to dig and finish it. A 40-foot shallow daylight trench in dirt takes about 9.3 crew-hours. An 80-foot deep drywell run in clay with two catch basins, three downspout ties, and a 15-foot driveway crossing takes about 45.3 crew-hours -- twice the footage, roughly five times the labor, because depth, soil, the outlet, and the extras do not scale with linear feet.
What does a flat per-foot rate usually miss entirely?
Trench depth, pipe size, soil type, the outlet, catch basins, downspout ties, and a driveway crossing. A flat rate has no line for the difference between an 18-inch trench in loam and a 36-to-48-inch trench in clay or rock, no line for daylighting to grade versus a drywell pit or a permitted storm tie-in, and no line for catch basins, downspout ties, extra solid pipe, or cutting and patching a driveway at all.
How big is the pricing gap in practice?
Using this calculator's own shipped cost inputs: a 40-foot shallow daylight trench in dirt takes 9.3 crew-hours and prices at $1,862.64 -- $46.57 per foot. An 80-foot deep drywell run in clay, with two catch basins, three downspout ties, and a 15-foot driveway crossing, takes 45.3 crew-hours, costs $6,177.40 to run before a dollar of profit, and this calculator prices it at $8,824.85 -- $110.31 per foot. Quoting the deep job at the shallow job's learned rate of $46.57 per foot gives $3,725.28 for eighty feet, which is $2,452.12 below the deep job's own break-even cost -- before counting the $5,099.58 it falls short of this calculator's price at a 30% target margin.
Is a flat price per foot ever a reasonable shorthand?
For a narrow band of similar jobs -- the same depth, soil, and outlet as the job the rate was learned on -- a per-foot number can land close. The risk is quoting a deeper trench, harder soil, a drywell or storm tie-in, or basins and a driveway crossing the same way sight unseen, because the rate does not know the depth, the soil, or the outlet until the trencher is in the ground, and by then the per-foot number has often already been quoted.
Does this calculator know my local labor rates or material costs?
No. It has no data on your local labor market or your supplier's pipe, gravel, or fabric pricing. It takes linear feet, depth, pipe size, soil, the outlet, catch basins, downspout ties, a driveway crossing, and extra solid pipe, plus your own wage, payroll burden, travel, overhead, and target margin, and turns that into crew-hours and a price for this job -- the arithmetic a flat per-foot rate skips, not a market survey.
Open the French Drain Bid Calculator to price your own job, or read how much to charge for a French drain.