Lump Sum, Unit Price and Cost-Reimbursable Pricing
In the PMI Construction Professional (PMI-CP) framework, pricing structures define how risk, payment, and control are shared between owner and contractor across the contract lifecycle, and they must align with the chosen delivery method. Lump Sum (Fixed Price) contracts set a single total price for a clearly defined scope. They suit projects with complete, stable designs, such as Design-Bid-Build after full documentation. The contractor carries most of the cost and productivity risk, which motivates efficient work, while the owner gains budget certainty and simpler administration. However, contractors add contingency for uncertainty, and any scope change triggers change orders that can lead to disputes. Incomplete or weak drawings undermine this model. Unit Price contracts pay a fixed rate per measurable unit of work, such as cubic meters of excavation, tons of steel, or linear meters of pipe, multiplied by the actual quantities installed. They fit heavy civil, infrastructure, and repetitive work where the type of work is known but the quantities are uncertain. Risk is shared: the contractor bears the unit cost risk, while the owner bears the quantity risk. Success depends on accurate quantity measurement and verification, plus clauses that address significant quantity variations. Cost-Reimbursable contracts pay the contractor actual allowable costs plus a fee. The fee may be fixed (Cost Plus Fixed Fee), a percentage of cost (Cost Plus Percentage of Cost), incentive-based (Cost Plus Incentive Fee), or capped through a Guaranteed Maximum Price. These contracts suit fast-track, early-design, emergency, or highly uncertain projects. They are common in Construction Management at Risk, Design-Build, and Integrated Project Delivery. The owner assumes most of the cost risk and must provide strong oversight, audits, and transparent cost reporting. For PMI-CP practitioners, selecting the right pricing model means evaluating scope definition maturity, risk allocation, schedule pressure, owner capability, and market conditions. The contract must then be actively managed through procurement, execution, change control, payment, and closeout to protect value and minimize claims.
Lump Sum, Unit Price and Cost-Reimbursable Pricing: A Complete PMI-CP Exam Guide
The PMI Construction Professional (PMI-CP) credential expects you to understand how contract pricing structures shape risk, behaviour, cash flow and project outcomes. Three foundational pricing models appear again and again in construction contracting:
1. Lump Sum (Fixed Price)
2. Unit Price (Measure and Value / Remeasurement)
3. Cost-Reimbursable (Cost-Plus)
This guide explains why these models matter, what each one is, how each works in practice, and how to answer exam questions about them confidently.
Why These Pricing Models Are Important
1. They allocate risk. Every pricing model decides who carries the risk of cost overruns, quantity changes and scope uncertainty. Lump sum pushes most cost risk to the contractor. Cost-reimbursable pushes most cost risk to the owner. Unit price shares it: the owner carries quantity risk and the contractor carries rate risk.
2. They drive behaviour. A contractor paid a fixed price is motivated to work efficiently, and sometimes to cut corners. A contractor reimbursed for all costs has little natural incentive to control spending unless incentives or caps are added.
3. They must match the level of design definition. Choosing the wrong model for the maturity of the scope is a classic cause of disputes, claims and failed projects.
4. They affect administration effort. Cost-reimbursable contracts require heavy auditing and cost verification. Unit price contracts require accurate measurement. Lump sum contracts require strong change control.
5. They link to delivery methods. Design-Bid-Build often uses lump sum. Construction Management at Risk often uses cost-plus with a Guaranteed Maximum Price (GMP). Design-Build may use lump sum or GMP. Civil and heavy works often use unit price.
What Each Pricing Model Is
1. Lump Sum (Stipulated Sum / Firm Fixed Price)
The contractor agrees to deliver a clearly defined scope of work for a single, fixed total price.
Key characteristics:
- Requires complete or near-complete design (typically 90 to 100 percent construction documents).
- The contractor carries the risk of cost overruns for the defined scope.
- The owner has high cost certainty at contract award.
- Payment is often based on percentage of completion against a schedule of values, or on milestones.
- Changes to scope require formal change orders, which are often expensive.
- The contractor includes contingency and risk premiums in the bid.
Best used when: scope is well defined, design is complete, site conditions are well understood, and the owner wants budget certainty and competitive bidding.
Disadvantages: long pre-award design time, higher bid prices due to risk pricing, adversarial change order environments, and little owner visibility into actual costs.
2. Unit Price (Remeasurement / Bill of Quantities)
The owner provides estimated quantities for defined work items such as cubic metres of excavation, linear feet of pipe or tonnes of rebar. The contractor bids a price per unit. Final payment equals the actual measured quantities multiplied by the agreed unit rates.
Key characteristics:
- The owner carries quantity risk, because quantities may vary.
- The contractor carries unit rate risk, meaning the cost of performing each unit of work.
- Common in heavy civil, highways, earthworks, utilities, pipelines and marine works.
- Requires accurate field measurement and verification.
- Contracts often include variation in quantity clauses, for example permitting renegotiation of rates if quantities change by more than 15 to 25 percent.
Best used when: the type of work is known but the exact quantities cannot be determined before construction, such as excavation in uncertain ground or repetitive work items.
Disadvantages: the final cost is not known at award, there is a risk of unbalanced bidding (front-loading or inflating rates on items the contractor expects to overrun), and measurement can be disputed.
3. Cost-Reimbursable (Cost-Plus)
The owner reimburses the contractor's actual allowable costs, plus a fee that covers overhead and profit.
Common variants:
- Cost Plus Percentage of Cost (CPPC): the fee is a percentage of actual cost. This gives the contractor no incentive to control cost and is often prohibited in public contracting, such as US federal work.
- Cost Plus Fixed Fee (CPFF): the fee is a fixed amount regardless of actual cost. This removes the incentive to inflate costs, but also provides no reward for saving costs.
- Cost Plus Incentive Fee (CPIF): the fee is adjusted by a pre-agreed share ratio based on performance against a target cost. Example: target cost 10M, target fee 1M, share ratio 80/20 (owner/contractor). If actual cost is 9M, the 1M saving is shared, the contractor earns 0.2M extra, and the fee becomes 1.2M.
- Cost Plus Award Fee (CPAF): an award fee is granted based on subjective owner evaluation of performance.
- Cost Plus with Guaranteed Maximum Price (GMP): costs are reimbursed up to a ceiling, and the contractor absorbs costs above the GMP. Savings below the GMP are often shared. This is very common in CM at Risk and progressive Design-Build.
Key characteristics:
- The owner carries most cost risk.
- Ideal when scope is undefined, evolving, urgent or highly complex.
- Requires open-book accounting, auditing and a clear definition of reimbursable versus non-reimbursable costs.
- Enables early contractor involvement and fast-tracking.
Best used when: design is incomplete, there is an emergency or schedule urgency, work is innovative, or the owner wants collaboration and transparency.
Disadvantages: low cost certainty, heavy administrative burden, and the need for strong owner oversight.
Related Hybrid: Time and Materials (T&M)
Labour is paid at agreed hourly rates (which include overhead and profit), and materials are paid at cost plus a markup. T&M is often used for small, undefined work, extra work or emergency repairs. It usually carries a not-to-exceed (NTE) cap. It combines features of unit price (the rates) and cost-reimbursable (open-ended quantities).
How They Work: Risk Spectrum Comparison
Picture a line from owner risk to contractor risk:
CPPC (highest owner risk) → CPFF → CPAF / CPIF → GMP → Unit Price → Fixed Price with Economic Price Adjustment → Firm Fixed Price / Lump Sum (highest contractor risk).
Selection Logic
- Design maturity high, scope stable: Lump Sum
- Work type known, quantities uncertain: Unit Price
- Scope undefined, fast-track needed, or high uncertainty: Cost-Reimbursable (preferably with incentives or a GMP)
- Small, undefined additional work: T&M with an NTE
Payment Mechanics
- Lump Sum: progress payments against a schedule of values, less retainage.
- Unit Price: measured quantities multiplied by unit rates in each payment period, verified by the owner's inspector or engineer.
- Cost-Reimbursable: invoices backed by receipts, payroll and documentation, then audited, with the fee applied as agreed.
Change Management
- Lump Sum: any scope change requires a priced change order. Watch for differing site conditions clauses and claims.
- Unit Price: quantity changes are paid automatically at the agreed rates. New item types need new rates. Large variations may trigger rate renegotiation.
- Cost-Reimbursable: scope changes flow naturally through costs. Under a GMP, scope changes adjust the GMP through change orders.
Worked Examples
Example 1: An owner has 100 percent complete drawings for a school and wants the lowest competitive price with budget certainty. Answer: Lump Sum through Design-Bid-Build.
Example 2: A highway project involves rock excavation, but borings show highly variable rock depth. Answer: Unit Price, so the owner pays for actual cubic metres excavated.
Example 3: A hospital must be repaired urgently after flood damage, and the full scope is unknown. Answer: Cost-Reimbursable or T&M with an NTE.
Example 4: An owner wants early contractor involvement during design but needs a cap on cost exposure. Answer: Cost Plus Fee with GMP through CM at Risk.
Example 5 (CPIF calculation): Target cost 500K, target fee 50K, share ratio 70/30 (owner/contractor), actual cost 560K. The overrun is 60K, and the contractor's share is 30% of 60K, which is 18K. The fee becomes 50K minus 18K, which is 32K. Total paid is 560K plus 32K, which is 592K.
Common Pitfalls Tested
- Using lump sum when design is incomplete, which leads to change orders, claims and disputes.
- Unbalanced bids in unit price contracts.
- Unclear definitions of allowable costs in cost-plus contracts.
- Assuming a GMP equals a lump sum. It does not, because a GMP is a cap on reimbursable costs and savings may return to the owner.
- Forgetting that the owner needs strong audit and oversight capability for cost-reimbursable contracts.
Exam Tips: Answering Questions on Lump Sum, Unit Price and Cost-Reimbursable Pricing
Tip 1: Identify the scope definition first. Look for clues such as 'complete drawings', 'quantities unknown', 'scope still evolving', 'emergency' or 'fast-track'. Scope maturity is usually the decisive factor.
Tip 2: Ask who bears the risk. If the question asks which contract puts the most risk on the seller or contractor, choose Firm Fixed Price / Lump Sum. If it asks which puts the most risk on the buyer or owner, choose CPPC or cost-reimbursable.
Tip 3: Unit price means the owner takes quantity risk. Memorise this phrase. The contractor guarantees the rate and the owner pays for whatever quantity is actually required.
Tip 4: Spot the incentive problem. If a scenario describes a contractor with no motivation to reduce costs, the answer typically involves CPPC or CPFF. The fix is usually an incentive fee, a GMP or shared savings.
Tip 5: Watch for 'best' versus 'possible'. Several models may work, but the exam asks for the most appropriate one. Match the model to the owner's priority, whether that is cost certainty, speed, flexibility or collaboration.
Tip 6: Know the GMP nuances. A GMP is cost-plus with a ceiling. Overruns above the GMP are borne by the contractor. Savings are often shared. It is commonly paired with CM at Risk.
Tip 7: Practise incentive fee maths. Use this formula: Fee = Target Fee + (Target Cost - Actual Cost) x Contractor Share. Check for fee floors and ceilings (minimum and maximum fees).
Tip 8: Remember administration requirements. Cost-reimbursable contracts need audit rights and open-book accounting. Unit price contracts need measurement and verification. Lump sum contracts need rigorous change control and a schedule of values.
Tip 9: Link pricing to delivery methods. DBB usually pairs with lump sum, CMAR with GMP, heavy civil with unit price, and emergency or IPD-style work with cost-plus or target cost.
Tip 10: Look for red flags in options. Answers that suggest switching to lump sum while the design is at 30 percent are usually wrong. Answers suggesting CPPC for public work are usually wrong.
Tip 11: Think like a project professional. PMI favours proactive risk management, collaboration, clear documentation and choosing contracts that align incentives with project objectives.
Tip 12: Eliminate distractors. Remove options that misallocate risk, ignore design maturity or create perverse incentives. Then choose the option that balances risk fairly given the scenario.
Quick Memory Summary
- Lump Sum: Known scope, fixed price, contractor risk, owner certainty.
- Unit Price: Known work type, unknown quantity, owner takes quantity risk, contractor takes rate risk.
- Cost-Reimbursable: Unknown scope, actual costs plus fee, owner risk, needs audits and incentives.
- GMP: Cost-plus with a cap, which protects the owner while keeping flexibility.
- T&M: Small or undefined work, rates plus materials, always use an NTE cap.
Final Thought
In the PMI-CP exam, pricing questions test your judgment rather than rote memory. Always connect the pricing model to scope certainty, risk allocation, incentives and the owner's priorities. If you can explain who carries which risk and why, you will answer these questions correctly.
PMI-CP - Lump Sum, Unit Price and Cost-Reimbursable Pricing Example Questions
Test your knowledge of Lump Sum, Unit Price and Cost-Reimbursable Pricing
Question 1
Under a cost-plus-fixed-fee contract, how does the contractor's fee respond when reimbursable costs exceed the original estimate for unchanged scope?
Question 2
A unit price earthworks contract lists rock excavation at 2,000 m3 at a bid rate of 50 per m3. The contract states that bid rates apply to final measured quantities and contains no rate adjustment clause. Midway through the work, 1,800 m3 has been measured and paid, and an updated geotechnical survey shows 1,200 m3 still to excavate. The sponsor's monthly cost report is due. What should the owner's project manager do NEXT?
Question 3
In a unit price contract, what is the role of the bill of quantities issued with the tender documents?