Construction Contract Comparison Calculator

Compare lump sum, GMP, and cost-plus construction contract types to understand owner exposure, contractor profit, and risk allocation.

Legal Disclaimer

This calculator provides general estimates only and does not constitute legal advice. Laws, regulations, and court procedures vary significantly by jurisdiction. Consult a licensed attorney in your area for advice specific to your situation.

Inputs

Estimated project cost ($)

Contract type (0=Lump Sum, 1=GMP, 2=Cost-Plus)

Contractor markup (%)

Contingency (%)

Expected change orders (%)

Project duration (months)

Tab to move between fields

Results

Owner max exposure ($)

$600,000.00

≈ 14 Teslas

Contractor profit ($)$125,000.00

Contingency reserve ($)$50,000.00

Change order exposure ($)$25,000.00

Monthly burn rate ($)$50,000.00

Owner risk score (0-100)25

Type NameLump Sum

Cost Per (sq ft) Equiv$240.00

How to Use This Calculator

Enter the estimated project cost and select a contract type: 0 for Lump Sum, 1 for GMP, or 2 for Cost-Plus.
Set the contractor markup %, contingency %, and expected change order % for the project.
Enter the expected project duration in months to see the monthly burn rate.
Review owner max exposure, contractor profit, contingency reserve, and change order exposure for the selected contract type.
Check the owner risk score (0-100) to see how exposed you are under this contract type — Lump Sum scores lowest, Cost-Plus scores highest.
Re-run the calculator with a different contract type value to compare exposure and risk across Lump Sum, GMP, and Cost-Plus.

How the result changes with Estimated project cost ($)

Estimated project cost ($)	Owner max exposure ($)
100,000,000	$120,000,000.00
350,000,000	$420,000,000.00
650,000,000	$780,000,000.00
900,000,000	$1,080,000,000.00

What each input means

Estimated project cost ($): Total estimated hard construction cost before markup.
Contract type (0=Lump Sum, 1=GMP, 2=Cost-Plus): 0 = Lump Sum (fixed price), 1 = GMP (guaranteed maximum price), 2 = Cost-Plus (reimbursable).
Contractor markup (%): Contractor's fee/profit markup on top of estimated cost. Typical range: 10-20%.
Contingency (%): Budget contingency for unknowns. 5-10% for renovations, 3-5% for new construction.
Expected change orders (%): Anticipated change orders as a percentage of project cost. Industry average is 5-10%.
Project duration (months): Expected construction timeline in months.

What each result means

Owner max exposure ($): Maximum total cost the owner could pay under this contract type.
Contractor profit ($): Estimated contractor profit including fee and any retained contingency.
Contingency reserve ($): Dollar amount set aside for unforeseen conditions.
Change order exposure ($): Estimated cost of change orders based on your percentage.
Monthly burn rate ($): Average monthly expenditure over the project duration.
Owner risk score (0-100): Relative risk to the owner: 25 = Lump Sum (low), 50 = GMP (moderate), 85 = Cost-Plus (high).

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Estimated project cost ($) = 500000, Contract type (0=Lump Sum, 1=GMP, 2=Cost-Plus) = 0, Contractor markup (%) = 15, Contingency (%) = 10 = 6 input(s) provided
Calculate Owner max exposure
Owner max exposure
600000 = $600,000
Calculate Contractor profit
Contractor profit
125000 = $125,000
Calculate Contingency reserve
Contingency reserve = projectCost * (contingencyPct / 100)
50000 = $50,000