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Change Order Calculator

Price a change order, including disruption.

Your measurementsEvery assumption editable01

Change orders normally carry a higher markup than base contract work.

Remobilising, resequencing and lost productivity on work already underway.

Change orderCalculated live02

Result

$3107.5change order

Contract moves to $45107.5 — up 7.4%

Original contract
$42000
Added materials
$1400
Added labor22 hr at $38
$836
Disruption allowance
$250
Direct cost of change
$2486
Markup25%
$621.5
Change order total
$3107.5
Revised contract7.4% increase
$45107.5

The disruption allowance is what separates a change order that pays from one that does not. Work inserted into a job already underway costs more than the same work planned from the start — remobilising, resequencing and the productivity lost while the crew changes tack are all real and all routinely given away free.

Change orders conventionally carry a higher markup than base contract work, and defensibly so. They are unplanned, they disrupt a schedule you priced around, and they carry more risk than work you scoped and bought materials for in advance.

Get it signed before the work starts. A change order agreed verbally and invoiced later is the single most common source of payment disputes in construction, and the position is far weaker after the work is already done.

Work inserted into a job already underway costs more than the same work planned from the start. The disruption allowance is what separates a change order that pays from one you effectively donate.

Why use this tool?What it does differently03

Why use this tool?

Disruption costed

Remobilising, resequencing and lost productivity — real costs routinely given away free.

Revised contract total

And the change as a percentage of the original, which is what a client will ask.

Higher markup, defensibly

Change work is unplanned, disruptive and riskier than what you scoped in advance.

Sign before you start

A verbal change invoiced later is the commonest source of payment disputes.

How this worksThe method04

How this change order calculator works

Added materials, added labor at your cost rate, and a disruption allowance give the direct cost of the change. Markup is applied to that total, and the result is added to the original contract.

Disruption is a separate line because it is a genuine cost that has nothing to do with the materials or hours involved. A crew that has to stop, resequence and remobilise loses productivity on work that was already priced, and that loss belongs in the change rather than absorbed silently.

The percentage of contract figure is included because it is the first thing a client asks, and because a series of small changes adding to twenty per cent of a contract is a conversation worth having early rather than at final invoice.

How to use itStep by step05

How to use it

  1. Step 1: Enter the original contract

    So the change can be shown in context.

  2. Step 2: Cost the added work

    Materials and labor hours at your cost rate, not your billing rate.

  3. Step 3: Add disruption honestly

    Remobilising and resequencing cost real money on work already underway.

  4. Step 4: Get it signed first

    Before any of the changed work begins. This is the whole ballgame on disputes.

Example usageWorked figures06

Example usage

A modest change
$1,400 materials, 22 hours at $38, $250 disruption: $2,486 direct, plus 25% markup gives a $3,107.50 change order. The contract moves from $42,000 to $45,107.50 — a 7.4% increase.
Without a disruption allowance
Dropping that $250 line takes the change to $2,795 — you have absorbed $312.50 of real cost including its markup.
Watching the total
Several changes reaching twenty per cent of contract value is a conversation to have at the third one, not at final invoice.
Frequently asked questionsCommon questions07

Frequently asked questions

How much should I mark up a change order?

Typically higher than base contract work — twenty to thirty per cent is common. The work is unplanned, disrupts a schedule you priced around, and carries more risk than what you scoped in advance.

What is a disruption allowance?

The cost of interrupting work already underway — remobilising, resequencing and the productivity lost while the crew changes tack. It is real, and it is routinely given away free.

Do I need a signed change order?

Always, and before the work starts. Changes agreed verbally and invoiced later are the single most common source of construction payment disputes, and your position is far weaker after the fact.

Should change orders be priced differently from the main contract?

Yes. The main contract was priced with the whole scope known and materials bought in bulk. A change has none of those advantages and should not carry the same margin.

What if changes keep accumulating?

Track the running total as a percentage of contract. Once it approaches ten to twenty per cent it is worth a formal conversation about scope rather than continuing to absorb it change by change.

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