Lump Sum Contract

One fixed price for a defined scope — the contractor owns the cost risk.

Quick Answer

A lump sum contract, also called a fixed-price or stipulated-sum contract, sets a single price for a clearly defined scope of work. The contractor is paid that amount regardless of what the work actually costs, keeping any savings and absorbing any overruns. It gives owners strong cost certainty but requires a complete, well-defined design.

The Full Picture

A lump sum contract exists to give the owner one clean, committed number and to put the cost risk on the party best positioned to manage the means and methods — the contractor. It's the default structure for competitively bid public work and for private jobs where the design is complete enough to price with confidence.

The mechanics are simple but demanding: the contractor prices the entire defined scope, adds contingency and markup, and offers a single figure. Once accepted, that figure holds. If the contractor's crews are more productive or material prices drop, the contractor keeps the difference. If they're less productive or prices rise, the contractor eats it. The owner's number doesn't move for the defined scope.

That risk transfer only works when the scope is genuinely defined. Because the contractor can't recover overruns, ambiguity in the drawings becomes a battleground: anything not clearly included tends to surface later as a change-order claim. Lump sum jobs live and die on the completeness of the construction documents and the rigor of the contractor's scope review during bidding.

In preconstruction, a contractor bidding lump sum has to be ruthless about scope. Every subcontractor bid must be leveled to a common scope so the contractor isn't unknowingly carrying — or missing — work. A gap discovered after award is the contractor's problem, which makes bid leveling and scope-gap detection the core defensive skill of hard-bid estimating.

Real Examples

→Public hard bid: A municipality issues complete construction documents; three GCs each submit a single lump-sum price, and the lowest responsive bid wins the fixed-price contract.

→Contractor keeps savings: The GC's steel sub beats the carried price by $80k; on a lump sum that savings stays with the contractor rather than being returned to the owner.

→Scope-gap exposure: The drawings imply but never clearly specify fireproofing at a mezzanine; because it's a lump sum, whether it's 'included' becomes a change-order dispute the contractor may lose.

Common Misconceptions

People assume: A lump sum guarantees the owner's final cost.

Actually: It fixes the price for the defined scope only. Owner changes, unforeseen conditions, and design errors still generate change orders. A lump sum controls cost growth from the contractor's execution, not from scope changes or incomplete documents.

People assume: Lump sum is always cheaper for the owner.

Actually: Because the contractor carries all the cost risk, they price contingency into the number to protect themselves. On a well-defined project that's efficient; on an ambiguous one, owners pay for risk that may never materialize — or fight change orders that do.

Does MeltPlan Solve This?

Partially — adjacent

On a lump sum, an undetected scope gap comes straight out of the contractor's margin — so complete, leveled bids are the whole game. MeltPlan levels every subcontractor proposal in minutes and flags scope gaps, exclusions, and qualifications, so nothing quietly falls between trade packages. Negotiating and executing the contract itself stays with your team.

Catch scope gaps before you sign a fixed price →

Frequently Asked Questions

What's the difference between a lump sum and a GMP?

A lump sum fixes one price and the contractor keeps all savings; the books stay closed. A GMP caps the maximum but is open-book, and savings below the cap are typically shared with the owner. Lump sum transfers more risk — and more upside — to the contractor.

When should you use a lump sum contract?

When the design is complete and the scope is well defined, so the contractor can price with confidence. It's common on competitively bid public work and on private jobs bid from finished construction documents.

Who bears the risk in a lump sum contract?

The contractor bears the cost and productivity risk for the defined scope — overruns come out of their margin. The owner retains risk for changes they direct, unforeseen site conditions, and errors in the documents they provided.

Is a lump sum contract the same as a hard bid?

A hard bid is the procurement method — competitive bidding from complete documents. It almost always results in a lump-sum contract, but 'lump sum' describes the pricing structure while 'hard bid' describes how that price was obtained.