Change Order Impact Calculator
Calculate the full cost impact of a construction change order including markup, schedule delay costs, and new contract value.
About this calculator
This calculator computes the full cost impact of a construction change order, including markup and schedule-delay cost. Markup Amount combines Overhead & Profit Rate applied to the absolute value of Change Amount with a fixed standard 10% profit on top, then Change Amount plus that markup (added if the change is a positive addition, subtracted if it's a negative deduction) becomes the contract adjustment. Change Amount dominates Markup Amount and Total Impact directly, since both are built from it.
Schedule Impact Cost is calculated separately from extended general conditions -- Schedule Days Impact times a daily rate equal to 0.015% of Original Contract Value per day -- so Original Contract Value and Schedule Days Impact together drive that line item, while Change Amount has no effect on it at all. A negative Change Amount (a deductive change order) still generates the same markup on its absolute value, but subtracts it from the deduction rather than adding it, and flips New Contract Value's direction: at the default $75,000 addition, New Contract Value rises to $2,093,750, while the same $75,000 entered as a deduction (−$75,000) lowers it to $1,906,250 -- both with the identical $18,750 markup and $3,000 schedule cost, since markup and schedule cost both depend on magnitude, not sign. This models a standard AIA-style change order markup; it doesn't account for contract- specific markup caps or negotiated reduced rates on deductive changes.
Inputs
Results
New Contract Value
$2,093,750.00
≈ 5 average U.S. homes
Total Impact
$96,750.00
≈ 9 years of state college
How to Use This Calculator
- Enter the current contract value before this change order.
- Enter the direct cost of the change in dollars (positive for additions, negative for deductions).
- Enter the schedule impact in calendar days the change adds to the project.
- Set the overhead and profit rate as a percentage to apply markup to the change amount.
- Read the new contract value, markup amount, schedule impact cost, and total change order impact.
How the result changes with Original Contract Value
| Original Contract Value | New Contract Value | Total Impact |
|---|---|---|
| $1,000,000.00 | $1,093,750.00 | $95,250.00 |
| $1,500,000.00 | $1,593,750.00 | $96,000.00 |
| $3,000,000.00 | $3,093,750.00 | $98,250.00 |
| $5,000,000.00 | $5,093,750.00 | $101,250.00 |
What each input means
- Original Contract Value
- Current contract value before this change order.
- Change Amount
- Direct cost of the change (positive for additions, negative for deductions).
- Schedule Impact
- Additional calendar days the change adds to the project schedule.
- Overhead & Profit Rate
- Combined overhead percentage applied to the change amount.
What each result means
- New Contract Value
- Updated contract value including the change order.
- Markup Amount
- Overhead and profit applied to the change.
- Schedule Impact Cost
- Extended general conditions cost from schedule delay.
- Total Impact
- Combined cost of change, markup, and schedule impact.
- Change as % of Contract
- This change order as a percentage of the original contract.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersOriginal Contract Value = 2000000, Change Amount = 75000, Schedule Impact = 10, Overhead & Profit Rate = 15 = 4 input(s) provided
- Calculate New Contract ValueNew Contract Value2093750 = $2,093,750
- Calculate Total ImpactTotal Impact96750 = $96,750
- Calculate Markup AmountMarkup Amount18750 = $18,750
- Calculate Schedule Impact CostSchedule Impact Cost3000 = $3,000
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Does a deductive (negative) change order still carry markup?
Yes -- Markup Amount is calculated from the absolute value of Change Amount, so a deduction generates the same dollar markup as an equivalent addition would. At the default magnitude, both a +$75,000 and a −$75,000 Change Amount produce an identical $18,750 markup; the difference is only in which direction it's applied to the contract total.
What determines the schedule impact cost?
Schedule Impact Cost is Schedule Days Impact times a daily extended general conditions rate equal to 0.015% of Original Contract Value -- so a larger original contract or more schedule days both raise this line item, while Change Amount has no effect on it at all, since schedule cost is calculated entirely separately from the direct change value.
How does a negative change amount affect the new contract value?
A negative Change Amount lowers New Contract Value instead of raising it -- at the default $2,000,000 contract, a +$75,000 change order raises New Contract Value to $2,093,750, while the same amount entered as a −$75,000 deduction lowers it to $1,906,250, even though the markup and schedule impact cost are identical in both cases.
What's included in the markup amount?
Markup Amount combines two pieces: Overhead & Profit Rate applied to the change amount, plus a fixed standard 10% profit markup that's always applied regardless of the Overhead & Profit Rate setting -- so even setting Overhead & Profit Rate to 0% still leaves the standard 10% profit component in the markup.
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