Construction Contract Comparison Calculator

The score is a fixed value assigned per contract type in the model, not a derived calculation: Lump Sum gets 25 because the contractor absorbs cost overruns and the owner's exposure is capped at cost plus markup plus expected change orders. GMP gets 50 because the price is capped by a guaranteed maximum, but change orders can still increase what the owner pays beyond that cap. Cost-Plus gets 85 because the owner pays actual costs plus contingency plus change orders in full, with the contractor earning only a fixed fee, leaving the owner exposed to essentially all overrun risk.

Under the model's GMP calculation, contractor profit is markup plus half of the contingency amount — reflecting the common real-world GMP structure where any contingency the contractor doesn't end up needing is shared as a savings incentive rather than kept entirely by either party. This is what distinguishes GMP's contractor profit from Lump Sum, where the contractor keeps 100% of unused contingency, and from Cost-Plus, where the contractor earns only the fixed fee with no contingency upside at all.

This figure backs into an implied square footage by assuming a flat $200/sqft baseline construction cost, then divides owner max exposure by that implied footage — it's a rough sanity-check proxy, not a real per-square-foot cost derived from your actual project size. For projects with unusually high-end finishes or heavily value-engineered budgets, where true cost per square foot is far from $200, this number will diverge significantly from what you'd get from an actual square-footage-based estimate, so use it only as a loose cross-check, not a benchmark figure.

Both figures are calculated purely from project cost times their respective percentages (contingencyPct and changeOrderPct) with no dependency on contractType, because the underlying risks — unforeseen conditions and scope changes — exist regardless of how the contract allocates who pays for them. What differs across Lump Sum, GMP, and Cost-Plus is only who bears those costs when they materialize, which is reflected in owner max exposure and contractor profit, not in the reserve and exposure line items themselves.