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Estimating & Bidding

Unit Price Contract

In Plain English

A contract where the contractor is paid a fixed rate per unit of work, with the total based on actual quantities completed.

Definition

A unit price contract is a contract type in which the owner pays the contractor a fixed price per unit of measured work, such as per cubic yard of excavation or per linear foot of pipe. The total contract value is determined by multiplying the unit prices by the actual quantities installed. Unit price contracts are common for civil work where quantities are uncertain at bid time.

Why It Matters in Bidding

Unit price contracts shift quantity risk to the owner while keeping productivity and pricing risk with the contractor, so estimators must build each unit rate to fully recover labor, equipment, materials, overhead, and markup at the expected production rate. Accurate measurement procedures and clear pay-quantity definitions in the bid documents are critical, because disputes over how field quantities are measured directly affect payment and cash flow.

Example

Bidding a municipal water-main job, an estimator submits $62 per linear foot for 8-inch ductile pipe and $38 per cubic yard for rock excavation, knowing final payment will track surveyed field quantities rather than the engineer's estimated quantities.

Related Terms

Lump SumCost Plus ContractQuantity TakeoffBid Form

Frequently Asked Questions

Contractors sometimes load rates on items likely to overrun and reduce rates on items expected to underrun, a tactic called unbalanced bidding. While it can improve cash flow and total return, owners scrutinize it and may reject mathematically or materially unbalanced bids as nonresponsive, so estimators must keep rates defensible against the engineer's quantities.
Most unit price contracts include a variation clause, often triggered when a major item changes by more than 15 to 25 percent. Beyond that threshold either party can request renegotiation of the affected unit rate, since fixed overhead and mobilization assumptions no longer hold at the new quantity. Estimators should know this clause before pricing.
Unit pricing fits civil, earthwork, utility, and repair work where final quantities cannot be known at bid time. It lets owners advertise and award before complete quantity definition, while contractors avoid pricing large contingencies for unknown takeoff. Lump sum is better suited to fully defined building scopes with reliable drawings.

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