Overhead Cost Calculator

Overhead is the cost of being in business rather than the cost of building anything in particular. Construction accounting draws a line between two kinds of it. General and administrative overhead covers the office itself - rent, utilities, general liability and other insurance, administrative and estimating salaries, accounting and legal fees, software, marketing and non-project vehicles - and cannot be traced to any single job. Field or job overhead, often called general conditions, covers site-specific but non-productive costs such as the superintendent, temporary power, fencing, portable toilets and the site trailer, and belongs in the direct cost of that project. Mixing the two is a common source of double counting: general conditions charged to a job and then also recovered through the office overhead rate inflates the bid. The overhead rate expressed here is total indirect cost divided by direct cost, so a firm with 16,300 dollars of monthly office overhead against 150,000 dollars of monthly direct cost carries roughly an 11 percent rate and must add about 11 cents to every dollar of direct cost simply to break even. Rates for construction firms commonly fall between 10 and 25 percent, trending higher for smaller firms because fixed office costs are spread across less volume. The critical caveat is that this is a volume-dependent allocation, not a fixed property of the business. Overhead expense is largely fixed in the short run while the denominator fluctuates, so a rate calculated in a busy month will underrecover in a slow one. Recomputing quarterly against a realistic annual volume forecast, rather than a single strong month, avoids systematically underpricing work.

Distributing indirect expense across output became a formal accounting problem during the late nineteenth century, when factories grew large enough that machinery, supervision and building costs dwarfed the traceable materials in a product. Alexander Hamilton Church wrote influentially on the distribution of shop burden around 1901, arguing that indirect cost had to be allocated to work through defensible rates rather than left as an undifferentiated lump, and the vocabulary of overhead absorption entered general accounting practice from that debate. Construction inherited the method and then had to make it legally precise, because on public work the question of which overhead a contractor may recover is contested money. United States federal contracting rules, now codified in Part 31 of the Federal Acquisition Regulation, define which indirect costs are allowable and how they may be allocated, and they explicitly disallow categories such as advertising and lobbying. Delay claims produced a further refinement: when a project is suspended, a contractor continues to incur home office overhead that cannot be reallocated to other work, and a formula for apportioning that unabsorbed overhead emerged from a dispute involving the Eichleay Corporation decided by the Armed Services Board of Contract Appeals in 1960. The Eichleay formula is still the standard approach for extended home office overhead claims in the United States. More recently, activity-based costing, developed by Robin Cooper and Robert Kaplan in the late 1980s, offered an alternative to spreading overhead by a single volume-based rate.