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Change Order Calculator

Calculate the full cost impact of construction change orders — labor, materials, overhead & profit.

Change Order Details

Cost Components

Markup

Cost Breakdown

Labor Cost $0.00
Material Cost $0.00
Subcontractor Cost $0.00
Equipment Cost $0.00
Direct Cost Subtotal $0.00
Overhead (15%) $0.00
Subtotal + Overhead $0.00
Profit (10%) $0.00
Total Change Order Value $0.00
Overhead applied to direct costs. Profit applied to (direct costs + overhead).

Change Order Log

0 orders
CO # Title Status Direct Cost Overhead Profit Total
No change orders added yet. Use the Single Change Order tab to add COs.

Contract Values

Change order totals are pulled automatically from your CO Log. Approved and pending COs are tracked separately.
Original Contract Value $0.00
Approved COs Total $0.00
Pending COs Total $0.00
Revised Contract Value $0.00
Change Order % of Original 0.00%

Contract Impact Chart

Chart: contract chart.

Pending COs are not included in revised contract value. Approved only.

How to Use the Change Order Calculator

1
Enter the CO Number and Date. Use a sequential numbering format like CO-001, CO-002. A consistent numbering scheme makes it easy to reference change orders in correspondence, pay applications, and dispute resolution.
2
Describe the scope change clearly. Write a concise title and description that explains exactly what is being added, removed, or modified. Vague descriptions are a leading cause of payment disputes — be specific about location, material specifications, and affected trades.
3
Enter all direct cost components. Input labor hours and hourly rate separately so the calculator shows the cost transparently. Enter material costs at your cost (not retail), subcontractor quotes as lump sums, and any equipment rental or mobilization costs.
4
Set your Overhead and Profit percentages. Overhead (10–20% is typical) covers indirect business costs applied to direct costs. Profit (5–15%) is applied to direct costs plus overhead. Many contracts — especially public works — specify a maximum combined O&P cap; check your contract before setting these values.
5
Set the status and add to the log. Mark the CO as Pending until the owner signs it. Once signed, change the status to Approved. The Contract Summary tab tracks approved and pending totals separately and updates the revised contract value in real time.
6
Monitor the Contract Summary. Enter the original contract value on the Contract Summary tab to see the full financial picture: approved CO impact, pending exposure, revised contract total, and CO percentage of the original contract. Export the log to CSV for use in pay applications or project management software.

Change Order Formulas

Labor Cost Labor Hours × Hourly Rate
Direct Cost Labor + Materials + Subs + Equipment
Overhead Amount Direct Cost × (Overhead % ÷ 100)
Subtotal + Overhead Direct Cost + Overhead Amount
Profit Amount (Direct Cost + Overhead) × (Profit % ÷ 100)
Total Change Order Value Direct Cost + Overhead + Profit
Revised Contract Value Original Contract + Sum of Approved COs
CO % of Original (Approved CO Total ÷ Original Contract) × 100

Formulas & Methods

V

inp.value.replace(/[^\d.]/g, '')

Labor Cost

laborHours * laborRate

Overhead

directCost * (ohPct / 100)

Key Terms

Change Order (CO)A written amendment to a construction contract that modifies the original scope of work, contract price, or project schedule. All three parties — owner, architect/engineer, and contractor — must sign for a CO to be contractually binding.
Direct CostsCosts directly tied to performing the change order scope: labor, materials, subcontractor work, and equipment. These must be documented with time sheets, invoices, and quotes to support payment.
OverheadIndirect costs of running the business that cannot be attributed to a single project — insurance premiums, office rent, project manager salaries, vehicle costs, and licensing fees. Overhead is expressed as a percentage of direct costs and typically ranges from 10–20%.
Profit MarkupThe contractor's margin above all costs. In this calculator, profit is applied to the sum of direct costs plus overhead — the same base used in most AIA change order forms. Profit typically ranges from 5–15% and compensates for financial risk, scheduling disruption, and entrepreneurial reward.
O&P CapA contractual limit on combined overhead and profit, common in public works and insurance restoration contracts. A typical cap is 15% overhead + 10% profit (25% combined), though AIA contracts and state DOT specs vary. Always check your contract's change order clause.
Pending COA change order that has been submitted but not yet signed by the owner. Pending COs represent financial exposure — costs you may have already incurred or committed to without a signed agreement. The Contract Summary tracks pending totals separately from approved totals.
Revised Contract ValueThe updated contract total after factoring in all approved change orders. Calculated as: Original Contract Value + Sum of All Approved CO Totals. Pending COs are excluded until approved and signed.
Force AccountA method of compensating a contractor for changed work on a time-and-materials basis with agreed markup rates, rather than a fixed-price CO. Used when scope is difficult to define in advance. Requires detailed daily records including labor time sheets and material receipts.
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Real-World Examples

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Office Renovation CO-007 -- Electrical Panel Upgrade

4,000 sq ft office renovation discovers undersized 200A panel

Scenario: Midway through demolition on a $320,000 office renovation, the electrician discovers the existing 200A panel is undersized for the new lighting and HVAC equipment. The owner agrees to upgrade to a 400A service. The contractor prices CO-007 with labor ($1,520 -- electrician 16 hrs at $95/hr), materials ($3,840 -- 400A panel, breakers, conduit, wire), subcontractor coordination ($450), and equipment rental ($280). Direct cost subtotal: $6,090.

Result: With 15% overhead ($913.50) and 10% profit ($700.35), the total CO-007 value is $7,703.85. The revised contract becomes $327,703.85 -- a 2.41% increase. The contractor submits the CO with supporting invoices and time sheets before continuing work, protecting payment rights under the change order clause.

Understanding Change Order

What Is Change Order?

Change Order is a fundamental concept that this calculator helps you understand and apply. Whether you're a beginner or experienced professional, having precise calculations at your fingertips saves time and reduces errors.

Why It Matters

Understanding change order helps you make informed decisions backed by data rather than guesswork. Small miscalculations can compound into significant errors, making accurate tools essential for planning and analysis.

How It Works

The Change Order Calculator applies established formulas and methodologies to your specific inputs. Results update in real-time, letting you experiment with different scenarios to find the optimal approach for your situation.

Tips & Best Practices

  • Start with realistic values — use actual data when available rather than rough estimates for more meaningful results.
  • Compare scenarios — try different input combinations to understand how each variable affects the outcome.
  • Save your work — use the Share button to bookmark specific calculations for future reference.
  • Consult professionals — for critical decisions, use calculator results as a starting point and verify with a qualified expert.

Frequently Asked Questions

What is the difference between a change order and a work directive?+

A change order is a fully executed, signed amendment to the contract — it is binding on all parties. A work directive (or construction change directive under AIA contracts) is issued by the owner or architect to authorize the contractor to proceed with changed work before the price is fully agreed upon. The contractor must comply, and the final price is resolved later. Always document any work you perform under a directive and submit your priced CO as soon as possible.

How is overhead calculated on a change order?+

Overhead is calculated as a percentage of the direct costs for the change order scope (labor + materials + subcontractors + equipment). Common overhead rates run 10–20%, covering insurance, office expenses, supervision, vehicle costs, and project management time. Your actual overhead rate is determined by dividing your total annual indirect costs by your total annual direct costs.

What is a reasonable profit margin on a change order?+

Typical contractor profit margins on change orders range from 5–15%. Many contracts — especially public works and insurance jobs — specify a maximum O&P cap, often 15% overhead and 10% profit. On private commercial and residential projects, the markup is negotiated. Change orders carrying higher risk, tight schedules, or complex coordination often justify higher margins than the base contract work.

Should I add profit on top of a subcontractor's price?+

Yes. When you manage and coordinate a subcontractor as part of a change order, you take on coordination risk, schedule responsibility, and payment risk. Standard practice is to apply the same overhead and profit percentages to subcontractor costs as to your own labor and materials. Many contracts explicitly permit this. Only exclude sub markup if your contract specifically prohibits it.

What documentation should I attach to a change order?+

Supporting documentation should include: labor time sheets with employee names and hours, material invoices or supplier quotes, subcontractor proposals or signed sub-tier contracts, equipment rental invoices, photographs of the changed condition, and a reference to the specification section or drawing that drove the change. Thorough documentation prevents disputes and is required for most lien and bond claims.

Can a change order reduce the contract price?+

Yes. A deductive change order removes scope from the contract and reduces the contract price accordingly. In this calculator, you can enter the costs for the deleted work and treat the resulting total as a credit. Track deductive COs in the log — when set to Approved, they will correctly reduce the revised contract value in the Contract Summary tab.

What happens if I start changed work without a signed change order?+

Performing work without a signed change order is one of the most common causes of unpaid construction claims. Most contracts include a "no oral modifications" clause that bars payment for unauthorized work. Always get a written directive or signed CO before starting changed work — or at minimum, send a written notice reserving your right to additional compensation before proceeding.