Fence Installation Estimate Came In Too Low: Posts and Grade

Short answer: When a fence installation estimate came in too low, the linear foot is what hid the cost. Price per foot buys pickets and rails; posts are the labor, and 100 feet with six corners needs about 19 posts against 14 on a straight run, plus deeper footings at every corner and gate. Recount posts, concrete bags, and gates before the auger comes off the trailer — after the posts are set, nothing moves cheaply.

You are eleven holes into a job you priced by the foot, the auger is bouncing, and the customer’s yard turns four more times before it gets to the gate. Fencing is sold in a unit that describes the fence and says nothing about the work. The paperwork at the end is ordinary, and what to include on an invoice covers it. What matters right now is which of the four fencing-specific quantities you undercounted, because each one closes at a different moment.

Why does a price per linear foot hide the cost of a fence?

Because the customer buys a line and you build a series of holes. Material scales with the line. Labor scales with the post count, and post count is set by turns, not by length.

100 linear feet of fence	Spans	Posts	Corner or end posts
One straight run, 8 ft on center	13	14	2
One straight run, 6 ft on center	17	18	2
Six segments around a yard, 8 ft on center	18	19	7
Six segments, 6 ft on center	24	25	7

Two things happen when a run turns. Every segment rounds up on its own, so six short runs waste more span than one long one. And every turn creates a post that carries tension from two directions, which means a bigger hole, more concrete, and often a heavier post.

That is why panel systems land so differently from stick-built. A vinyl or aluminum system on 6-foot centers puts nearly twice the posts in the ground as a stick-built wood fence on 8-foot centers over the same footage. Quoting a panel system at a per-foot number carried over from wood is one of the most common ways this trade loses a job’s entire margin before the first picket goes on.

How much concrete goes in the ground before a single picket?

More than most bids account for, and all of it gets carried by hand.

An 80-pound bag of ready-mix yields roughly 0.6 ft³ and a 60-pound bag roughly 0.45 ft³ — check the bag you actually buy, since fast-setting and standard mixes differ. Now run the holes:

Hole	Volume	Less the post	Bags at 0.6 ft³
Line post, 10 in auger × 30 in deep	1.36 ft³	about 1.15 ft³	2
Corner or gate post, 12 in auger × 36 in deep	2.36 ft³	about 1.75 ft³	3

Apply that to the two layouts above. The straight run comes out near 30 bags, about 2,400 pounds. The yard with six turns comes out near 44 bags, about 3,500 pounds. On identical linear footage, that is over half a ton of extra material, wheeled or shouldered from wherever the truck could park.

Depth is a regional multiplier that quietly destroys a rate copied from somewhere else. The common guideline puts a third of the post in the ground, so a 6-foot fence uses a 9-foot post set 3 feet deep. Where the frost line sits deeper than that, the footing goes deeper still, which means longer posts, more auger time, more spoil, and more bags per hole. A per-foot price that works where the frost line is 12 inches does not survive where it is 48.

Did I quote a level yard and get a graded one?

This is the fencing-specific trap that no photo ever shows, because a slope looks like nothing in a picture taken from the street.

There are two ways to follow grade and they cost different amounts:

• Racking, where the rails follow the slope and the pickets stay plumb. Stick-built wood fences rack well with swivel brackets. Many aluminum panels rack too, but only up to a rise limit printed in the manufacturer’s spec — past that limit the panel has to be stepped instead.
• Stepping, where each section stays level and drops at the post. This is what vinyl panels and pre-assembled sections require, because a welded or routed panel cannot deform. Every step needs a taller post, a section cut to fit, and a triangular gap at the bottom that the customer will notice the first time a dog looks at it.

The gap is where the second cost hides. Closing it means grading fill, a kickboard, or a run of retaining timber, none of which appear in a per-foot price and all of which have to be discussed before you set posts. Walk the line with a level and a story pole at the site visit, not with your eyes from the driveway.

What did the auger hit?

Digging is the only quantity in this trade you genuinely cannot see from the surface, and it swings labor by a factor you can feel in your shoulders.

An auger in good soil sets a line post hole in a couple of minutes. The same hole in shale, in caliche, in heavy clay, or under a maple’s root plate becomes a clamshell digger, a rock bar, and thirty to ninety minutes on one hole. Old chain link is its own category: every original post is sitting in a concrete plug that either comes out of the ground or forces your new post to move, and moving one post changes the spacing on both sides of it.

The honest way to bid this is to say so. Price the fence on normal soil, name that assumption in the estimate, and put a stated hourly rate or per-hole adder on rock, roots, and buried footings. Customers accept a condition they were warned about far more readily than a surprise they were not.

What else falls off a fence takeoff?

The items sold in units other than feet.

• Locates. Contacting 811 before digging is free and required by law in most states, and utilities generally need a couple of business days to mark. Two effects on price: the wait is schedule, and a marked line under a planned post moves the post, which changes the spacing and sometimes the count.
• Tear-out, in linear feet and in disposal volume. Removing 100 feet of old fence is a separate line from installing 100 new, and the concrete plugs are the labor, not the panels.
• Gates, each — never as linear feet. A 4-foot walk gate is two heavier posts, hinges, a latch, and a brace. A 12-foot double drive gate is deeper footings on both sides, a drop rod, a cane bolt, and anti-sag hardware, because the whole weight hangs off one post in cantilever. Selling a drive gate as twelve feet of fence is the single most expensive line item error in this trade.
• Hardware and fasteners. Post caps, brackets, ring-shank or coated screws sized to the material, and tension bands and fabric ties on chain link, which are counted per post and per foot of top rail.
• Layout. String lines, batter boards, grade stakes, and the time spent confirming the property line before anything goes in the ground.
• Access and carry. Panels that will not fit through a 36-inch gate, a backyard the truck cannot reach, and a hundred pickets moved by hand.
• Haul-off. Old fence, spoil from the holes, and pallet trash.

Can I still correct the price once I have started?

The windows in fencing are unusually clear, because the job is physically staged.

Before locates come back, everything is still on paper. Before the first hole, the layout is walked and the post count is countable by both of you. Between the posts being set and the panels going on, you can still price added holes, rock, or a grade solution, since nothing structural has been closed.

Once the posts are concreted and the panels are hung, there is nothing left to negotiate. Concrete does not come back out of the ground on a change order.

Write the correction the day you find it, not the day you finish:

Field	What goes in it
Date and reference	Date found, the run or side of the yard, your bid number
Condition	Rock at post 7 through 11, or a 22-inch fall across the north line, with a photo
Quantity	Added posts, added holes, bags of concrete, linear feet of kickboard, hours of hand digging
Rate	Your per-post, per-foot, or per-hour rate with a not-to-exceed cap
Schedule	Added days, including any wait on re-marking
Approval	Name, date, and how it was given

Keep the approval reply. A text quoting the amount and the date does most of the work on residential fencing, and if the balance turns into a collection problem it is the beginning of the sequence in how to get clients to pay.

Why is walking off a fence job worse than eating the loss?

Because a partial fence is not partially useful — it is a hole in a perimeter, and the perimeter usually exists for a reason.

The customer bought this fence for a dog, a toddler, a property line dispute, or a pool. Pool barriers in particular are governed by code, and a yard left with a gap is not merely unfinished, it is a condition the homeowner may be legally obligated to fix immediately. Nobody else will take over a half-set fence at your price either, because the next contractor inherits your layout, your spacing, and your liability.

So the calculation is narrow. Run the cost to complete against what is left to collect. If the remaining balance covers the remaining panels, hardware, and labor, finish it — a fence that goes up straight, plumb, and closed sells the next three jobs on that street, and fencing is a trade where the product advertises itself from the sidewalk for a decade.

Absorb the loss when the miss is your own count, your own soil assumption, or a grade you did not walk. Do not absorb it when the customer moved the line, added a gate, changed the material after the bid, or when the locates forced a rerouting nobody could have known about. Those are documented conditions and they belong in a signed change order.

How do I rebuild the price per foot so the next one holds?

Stop pricing the fence and start pricing the parts of it.

1. Split the units. Posts each. Holes each, by soil condition. Concrete by the bag. Panels or pickets and rails by the foot. Gates each, by width and by leaf. Tear-out by the foot. Haul-off by the load.
2. Count posts off the layout, not the total footage. Segment the run, round each segment up, add every corner, end, and gate post, then count how many of those need the bigger hole.
3. Convert holes to bags with the yield printed on the bag you buy, adjusted for the post you are setting.
4. Get hours from your own crew, separately for layout, digging, setting, hanging, and gate hanging — gates always take longer than anyone remembers.
5. Load the hour. Wage plus payroll burden, truck and trailer, auger or skid steer, saws and bits, insurance, and the annual fixed cost divided across the hours you actually sell.
6. Add profit as margin, not markup. Add 20 percent to $6,000 of cost and you bill $7,200 and keep 17 percent. To keep 20 percent you divide by 0.80 and bill $7,500. Markup multiplies, margin divides, and the gap compounds across a season.

Published per-foot ranges for wood, chain link, vinyl, and aluminum are a check that you are not off by half. They swing on material, height, post spacing, frost depth, soil, access, and grade, so treat them as a sanity check and never as a price. The invoice you write at the end should carry the same split, which is what how to invoice after a backyard fence works through.

What paperwork makes the correction stick?

The marked-up layout with post positions and counts, the locate ticket number and its expiration, dated photos of the grade and of anything the auger hit, the material receipts, and the signed change orders with quantities.

Keel keeps that on the phone in your pocket in the middle of a back yard with no signal. It is an iOS app that runs entirely on the device — no account, no bank connection, no cloud, no login, and an App Store privacy label reading Data Not Collected. Lumberyard tickets, bag counts, and gate hardware receipts get photographed at the counter and read on device by Apple Intelligence, so a disputed quantity has a document behind it. The invoice goes out from the tailgate in about a minute, with your numbering, logo, and brand color, base run and approved additions on separate lines, and a payment link the customer scans as a QR code. Runs to the yard for one more bundle of pickets log as trips, which is exactly the record tracking mileage for taxes depends on in a trade that makes two supply runs a day. Freeboard shows cash minus tax reserve minus committed invoices minus your buffer. The ledger is append-only and hash-chained, and the year exports as one file or as an Accountant Pack of CSV plus a one-page summary PDF. Free is $0 with unlimited invoices, receipts, and mileage; Keel Pro is a one-time $249.99 Lifetime purchase, not a subscription.

Frequently asked questions

What do I do if my fence bid was too low?

Recount before you talk. Segment the run, round each segment up, add every corner, end, and gate post, and compare that number to what you priced. Then check grade, soil, and gate count. Condition changes and scope changes get a quantified change order before you dig. A post count you simply got wrong is a lesson, not a bill.

How many fence posts do I need for 100 feet?

On a straight run at 8-foot centers, 14 posts. At 6-foot centers, 18. The same 100 feet broken into six segments around a yard needs about 19 at 8-foot centers, because every segment rounds up independently and every turn adds a corner post. Count posts off the layout, never off the total footage.

How much concrete does one fence post take?

A 10-inch hole 30 inches deep holds about 1.36 ft³ before the post displaces some of it, which is roughly two 80-pound bags. A 12-inch hole 36 inches deep for a corner or gate post is closer to three. Bag yields run about 0.6 ft³ for 80 pounds and 0.45 ft³ for 60, so verify against the bag you buy.

Do I have to call 811 before setting fence posts?

In most states it is a legal requirement, it is free, and utilities generally need a couple of business days to mark. Fence holes run 2 to 3 feet deep, which is deep enough to reach shallow cable, fiber, gas, and irrigation. Marks also change the job, since a line under a planned post moves the post and changes the spacing.

Can I charge extra when the ground turns out to be rock?

Yes, if the estimate said what soil it assumed. Price the fence on normal digging, state that assumption in writing, and attach a per-hole or hourly rate for rock, roots, and buried concrete. Then document it the day you hit it, with a photo and the hole numbers, and get approval before you keep digging.

Should a gate be priced by the foot?

No. Gates are priced each, by width and by leaf count. A gate is two upgraded posts with deeper footings, hinges, a latch, bracing, and on a drive gate a drop rod and anti-sag hardware, because the leaf hangs in cantilever off one post. Folding a 12-foot double drive gate into linear feet of fence gives away the most labor-dense part of the job.

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This article is general information, not professional or tax advice.