How to use the construction contingency calculator
A contingency is money set aside for cost that is likely to appear but cannot yet be priced line by line. This calculator applies three separate risk rates to a base construction cost, so you can see how much each category contributes and what the total budget looks like once the allowance is added.
Splitting the rate matters because the three risks behave differently over the life of a project. Design risk falls as drawings are completed, escalation risk grows with the length of the schedule and the volatility of key commodities, and schedule risk depends on permitting, weather exposure and long lead items.
The effective contingency rate is simply the sum of the three inputs expressed against the base cost. Too high and the bid loses on price, too low and a single change order can erase the margin, so the number should reflect the actual state of the documents rather than a habit.
Contingency is a balance to be managed, not a figure set once at bid time. Reviewing the remaining allowance against the remaining unknowns at each monthly cost review keeps the job from running out of cover in the final months.
Frequently asked questions
It depends mainly on how far the design has progressed. Conceptual estimates commonly carry 15 to 20 percent, design development estimates 10 percent, and a fully detailed bid with confirmed quantities 3 to 5 percent. The allowance should shrink as unknowns are resolved.
Design change, price escalation and schedule delay have different causes and different mitigations. Tracking them separately lets you see which risk actually consumed the money at the end of the job, and gives you evidence for setting the rate on the next project.
It depends on the contract. On a lump sum contract unspent contingency generally stays with the contractor as margin, while on cost plus or guaranteed maximum price contracts the contract usually returns some or all of it to the owner through a savings clause.