A contractor calculator is not one calculation but the handful a small contractor runs on every job: the quantities from the drawings, the material takeoff at the yard's prices, the labor at the crew's rates, the site work as its own line, and the estimate that adds them up with contingency and overhead and profit. The online construction calculator a contractor searches for is usually one of those, and the free tools on this site are each one of them done properly: a concrete calculator for the pour, a cost estimator from the contractor's own cost per square foot, and a schedule-of-values draw for the billing. This page says which sum is which, works each on the hub's own example, and points at the tool that does it, with no account.
Quantities: the online construction calculator for the pour, the wall and the floor
Every quantity is the drawing's dimensions worked into the unit the material is sold in: cubic yards for concrete and gravel, sheets for drywall and sheathing, pieces by length for framing, blocks for a masonry wall. The concrete calculator on this site takes the slab's length, width and thickness, the contractor's waste allowance and the supplier's price per yard, and returns the yards and the cost; on the worked pad, 18 by 18 feet at 6 inches, 6.6 yards with 10% waste, $990 at $150 a yard. The other quantities are worked on their own pages here from the same rule: dimensions in feet, the unit's divisor, the allowance, the supplier's price.
The material estimator calculator and the material take off calculator
A material takeoff is the list of every quantity on the job at the yard's prices: the concrete by the yard, the lumber by the piece and the board foot, the sheathing and drywall by the sheet, the block by the unit, the roofing and siding by the square, each with its waste allowance and each priced from the supplier's quote. The material estimator calculator is that list summed, and it is the material half of the estimate. A takeoff engine that reads the plans and counts is a product the charter leaves to the estimating ventures; the arithmetic of turning the count into a priced list is the contractor's and this site's, and estimate building materials is what the list is for.
The construction labor calculator and site work estimating
Labor is the crew's rate times the hours or the unit rate times the quantity: framing at the contractor's rate per square foot of floor or per linear foot of wall, drywall at the rate per sheet hung and per square foot finished, concrete finishing at the rate per square foot for the finish specified. The construction labor calculator is those rates times the quantities from the takeoff, and the rates are the contractor's own, set from their crew's cost and their burden. Site work estimating is its own line because it is measured differently, in cubic yards moved, hours of machine and feet of utility trench, and priced at its own rates; the cost estimator on this site carries site work as a separate figure for that reason, $25,000 on the worked example.
The estimate: contingency, overhead and profit on the contractor's own numbers
The estimate is the materials plus the labor plus the site work, with contingency at the contractor's percentage and overhead and profit at theirs. On the hub's worked example, 2,000 square feet at the contractor's own $165 per square foot is $330,000 of building, $355,000 with $25,000 of site work, $35,500 of contingency at 10% and $58,575 of overhead and profit at 15%, a $449,075 estimate to the owner with every line shown. The free construction cost estimator on this site works that from your own cost per square foot, and the schedule of values on this site turns the signed estimate into the draw. The Small Business Administration's guide to managing a small business's finances, linked below, is the plain-language reference for the overhead the markup has to cover.
Questions people ask about contractor calculator
What does a contractor calculator calculate?
The sums a small contractor runs on every job: quantities from the drawings, the material takeoff at the yard's prices, labor at the crew's rates, site work as its own line, and the estimate with contingency and overhead and profit. The free tools on this site do each from your own figures.
Is there a free online construction calculator for quantities?
Yes. The concrete calculator on this site works the pour from the slab's dimensions, your waste allowance and your supplier's price, and the quantity pages here work drywall, framing, sheathing, block, gravel and sand from the same rule, with no account.
How is a construction labor calculator different from a material takeoff?
The takeoff is quantities at the supplier's prices; the labor calculator is the same quantities at the contractor's own rates per unit or per hour. Both feed the estimate, which adds site work, contingency and overhead and profit.