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Construction 3 Excel tabs included 9 min read Updated Jan 2026

Construction change order log calculator

Price change orders properly — cost impact, markup, delay days and contingency consumption — and see the cumulative change percentage before it becomes a dispute.

Healthy CO volume
< 10%
Contingency range
3–10%
Typical CO markup
10–20%
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Change orders decide whether the job made money

Base contracts are priced optimistically and then interrupted by reality: unforeseen rock, an owner upgrade, a design revision at the stair core. The change order process is where the profit on a construction project is either preserved or quietly surrendered. Contractors who track change volume against contingency and bill delay cost capture margin that competitors leave on the table.

The metric to watch is cumulative change value as a percentage of the original contract sum. Under 10% is normal on a well-documented job. Above 15% you are no longer executing a contract — you are renegotiating one, and the owner will treat it that way.

How to price a change order without arguing

Owners approve documented costs and reject lump sums. Build every change order from four components and attach the backup for each.

Change order total impactlive formula
Total impact = Direct cost
             + (Direct cost × markup %)
             + (Delay days × delay cost per day)
Delay cost should be calculated from your actual extended general conditions — supervision, equipment standing time, temporary facilities — not from a round number.
Cost justification components
ComponentTypical shareBackup required
Material / equipment procurement40–45%Vendor quotes, dated
Direct labour (burdened)25–35%Timecards by classification
Subcontractor pass-through10–20%Signed sub quote plus scope letter
Equipment & crane time5–10%Rental invoice or internal rate sheet
General conditions extension3–6%Supervision hours during delay
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Contingency discipline: the number that saves the job

Contingency is not profit and must never be spent as profit. Its purpose is to absorb the scope the drawings did not describe. The discipline is simple: track consumption as a percentage and have a conversation with the owner when it crosses 60%.

A common failure is treating contingency as an allowance to be spent because it is there. When a $20,000 contingency on a $412,000 contract is 80% consumed at 40% completion, the correct action is not to keep spending — it is to flag the trend formally, in writing, while there is still time to change course.

  • Contingency of 3–5% for well-scoped work in your trade; 8–12% for renovation and undefined existing conditions.
  • Report contingency consumption monthly alongside the pay application.
  • Contingency below 20% remaining with more than half the job left is a red flag worth escalating.
  • Profit margin and contingency must be separate lines. Never fund an overrun out of margin.

Delay cost: the most commonly unbilled entitlement

When a change order adds days to the critical path, the contractor carries extended general conditions: supervision salary, temporary facilities, equipment standing time, insurance and bond extensions. This is a legitimate cost of the change and is routinely not billed because it requires daily records to support.

The fix is procedural, not legal. Capture daily manpower counts, equipment on site and weather, every day, in a format you could hand to an owner. The workbook includes delay days and a delay cost per day on every change line so the entitlement is calculated at the time of the change rather than reconstructed months later.

  • Record daily manpower, equipment and weather — it is the evidence base for every time-related claim.
  • Price delay cost at the same time as the direct cost of the change.
  • Preserve the schedule impact in writing, even when the owner declines to extend the contract time.
  • A change that adds days without adding compensation is a discount you did not choose to give.

How to use this tool

  1. Log the change as soon as it is requested. Record the description, the requesting party and the date. An unlogged change is the one that gets argued about eight months later.
  2. Build the cost with backup. Break the change into material, labour, subcontractor, equipment and general conditions. Attach quotes and timecards to the justification sheet.
  3. Apply markup consistently and price delay days. Use the base-contract markup and calculate delay cost from your extended general conditions per day.
  4. Watch the cumulative percentage. The workbook flags when cumulative change value crosses your alert threshold and tracks contingency consumption, so the conversation happens while it can still change the outcome.

What is inside the download

A change order register that prices cost impact, markup and delay days on every line, a cost justification sheet that documents the largest change with its backup requirements, and a revised contract summary with contingency and threshold risk flags.

  • Change Request Log — a separate worksheet in change-order-log.xlsx.
  • Cost Justification — a separate worksheet in change-order-log.xlsx.
  • Revised Contract Summary — a separate worksheet in change-order-log.xlsx.

Where these defaults come from

Every pre-filled value in the calculator above is listed below with its basis. None of it is proprietary to us — we do not run primary research. Statutory figures come from the regulator, fee schedules from the vendor that charges them, ranges from published industry surveys, and conventions are labelled as rules of thumb. When you have your own numbers, replace the default: the workbook formulas do not care where an input came from.

DefaultValue usedBasisSource
Change order markupShould match the base contract markup for the affected work, or the owner will audit the base bid.10–20%Rule of thumbNo authoritative source — industry convention
Project contingencyContingency sits above profit and must never be used to fund an overrun in margin.3–5% scoped, 8–12% renovationRule of thumbNo authoritative source — industry convention
Workers' compensationClass code drives the rate; the range spans clerical to roofing. Get this from your carrier — a wrong default here is a legal exposure, not just a modelling error.$0.30 – $15+ per $100 of payrollMarket surveyNCCI and state rating bureausWorkers compensation class codes and loss costsCited by name · link pending verification

Full source registry, verification status and review cadence: data sources & methodology.

Frequently asked questions

The same markup you used in the base contract for the affected work — typically 10–20% covering overhead and profit. Applying a different, higher markup to changes invites the owner to audit your base bid. If your base contract holds a lower margin because you expected volume, keep the change markup consistent unless the contract specifies otherwise.

Software that pairs with this model

These are the platforms our models are designed to work alongside, chosen because their pricing or data appears in the model itself. Some links are affiliate links — they cost you nothing, and they never influence a formula, a default value or a result.

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