Concrete Bid Calculator

A concrete bid is cost plus margin, and the cost has seven lines. Concrete as delivered, with whatever the plant bills on the ticket. Base, rebar, forms, and cure. Subs, like tear-out and haul-off. The pump. Equipment and rentals. Crew labor at the loaded rate, not the bare wage. And a share of overhead, charged per crew hour.

Add those up and you have the cost. Then divide by one minus your margin. Do not multiply. A 30% margin means the price is cost divided by 0.70, which is a 42.9% markup on cost. The demo driveway costs $7,841 and bids at $11,201. Our concrete job costing post priced the same job at $11,200, which is this number rounded to the hundred.

Skip a line and the bid looks fine until the job is over. A ContractorTalk poster who lost a driveway to a much lower bid in 2014 worked it backward: “The materials cost, permit and my insurance barely cover that, most of my crews labor (not including my labor) put me way over that, how can this be?” (typo his). The likely answer is that the low bidder never added up the same seven lines.

Concrete yardage is area times thickness, in cubic yards. Take square feet, multiply by thickness in feet, and divide by 27. A 680 square foot driveway at 4 inches is 680 × 4 ÷ 12 ÷ 27, about 8.40 yards. Add waste, then round up to what the plant will batch. The calculator adds 5% and rounds up to the next quarter yard, which makes the demo order 9 yards.

Order tight and the short load costs more than the extra yard would have. A Breaktime regular said it plainly in 2006: “if you run short and have to order a 1/4 more, its a two yard minimum” (typo his). A 2009 Heavy Equipment Forums thread on figuring concrete by the yard gave the same warning: “partial load charges will kill your wallet quick.” His plant had a five yard minimum and a $50 partial charge, at 2009 prices.

These are line items contractors report, not universal constants. The demo order of 9 yards clears the minimums those posters name, which is why its truck fees sit at $0. If your plant bills a fuel surcharge, tax, or wait time, put it in the truck fees field. Then it lands on the job, priced in advance.

Divide the bid by the slab area and you get the per-foot number. The demo is $11,201 over 680 square feet, or $16.47 per square foot, everything in. That is a check, not a starting point. Build the bid from cost first, then look at the foot price to see if it passes the smell test in your market.

Plenty of the per-foot numbers you hear leave something out, and the thread rarely says what. A 2010 ContractorTalk thread reported a rival doing builder flatwork at $2.50 a foot, concrete and rebar included, at 2010 prices. A South Dakota contractor answered that he “wouldn't dream of pouring for $2.50 but I know contractors who do.” Compare a turnkey foot only to a turnkey foot. A tear-out driveway with base, a pump, and haul-off is a different product from a builder slab on prepared grade.

The per-foot habit is also how scope gets missed. An excavation owner on Heavy Equipment Forums looked back in 2021: “Underbid many jobs, some jobs I didn't realize what was required and customers refused to pay extra so I lost.” Then: “It hurts loosing money on jobs though” (typo his). A line-by-line bid catches what a foot price hides. When the job is done, run the real numbers through the construction profit margin calculator to see what you kept.

The two lines concrete bids skip most are labor burden and overhead. Burden is what rides on top of the wage: payroll taxes, workers comp, liability insurance, time off. Comp on concrete crews tends to run steep. Overhead is the shop, the trucks, the insurance, and the office, and every job has to carry a piece of it. The burden math is in our complete guide to construction job costing. The full list of what belongs in a job cost is in How to Calculate Construction Job Costs.

On the demo driveway, wages alone and no overhead feel like $5,972 of cost. The real cost is $7,841. The gap is $717 of burden and $1,152 of overhead. Price the felt number for a 30% margin and you sell the job for $8,531, which leaves an 8.1% margin after the real cost. Nothing went wrong on that job. The math was short two lines.

A Heavy Equipment Forums owner put the overhead half in one line in January 2026: “Now with slow years that 20% markup does not cover all the over head expenses and I have to eat it out of my wages” (typo his). This calculator charges overhead per crew hour. A per-hour rate recovers nothing on material and subs. If your work is material heavy, the percent-of-cost method in the construction job costing calculator fits better. Either way, put the line in before you bid, not after.

The number you just ran is the plan on the day you send it. Then the pour happens. The subgrade fights back and the crew runs 12 hours over. On the demo, that takes the cost to $8,527 and the margin at the sold price to 23.9%. Nobody sees that on pour day unless the hours land on the job the day they happen.

One owner on Heavy Equipment Forums said in 2022 that his problem was “keeping track of my employee's time, my time, and what we are doing when, and for what job.” That is the gap SiteOps fills. Crews clock in with GPS at the slab, and the hours land on that job the same day. A daily P&L per job shows what the pour is making. See how SiteOps tracks job costs while the job is running, starting with GPS-verified time tracking that puts real hours on the right job.