Scope change cost calculator.
Put in the hours, your rate, the non-hour costs, your contingency, and your markup. The calculator shows every step from effort cost to the amount a client pays including GST, carries the working days the change adds, and copies the whole thing to your clipboard as CSV so the same numbers land in the change request. It starts on an illustrative example so you can check the arithmetic before you type.
Work the change
Change any figure and every line recalculates. Nothing is sent anywhere, and nothing is stored.
- Effort cost (hours × rate)
- ₹60,000.00
- Direct cost (effort + other)
- ₹66,000.00
- Contingency
- ₹6,600.00
- Total cost of change
- ₹72,600.00
- Markup
- ₹18,150.00
- Net addition before GST
- ₹90,750.00
- GST
- ₹16,335.00
- Total addition including GST
- ₹1,07,085.00
- Schedule impact
- 8 working days
Quote the change at₹90,750.00before GST, or ₹1,07,085.00 with the 18% tax shown above.
The form starts on an illustrative example so you can see the arithmetic before you type. The rate, contingency, and markup are your own decisions — this calculator does not suggest what they should be, and the GST rate shown is a figure to confirm with your chartered accountant for the supply in question.
The form opens on an illustrative example — 48 hours at ₹1,250.00, ₹6,000.00 of other direct cost, 10% contingency, 25% markup, 18% GST, 8 days of schedule impact. These are invented numbers for the example, not recommended rates. There is no “industry standard” markup or contingency, because we have no honest source for one.
The worked example, in full
The same example written out, so you can check each line by hand against the calculator above.
Inputs
- Effort hours
- 48
- Hourly rate (INR)
- 1,250.00
- Other direct costs (INR)
- 6,000.00
- Contingency
- 10%
- Markup on cost
- 25%
- GST rate
- 18%
- Schedule impact
- 8 working days
Step by step
| Line | How it is worked out | Amount (INR) |
|---|---|---|
| Effort cost | 48 hours × ₹1,250.00 | 60,000.00 |
| Direct cost | Effort plus ₹6,000.00 of other direct cost | 66,000.00 |
| Contingency | 10% of ₹66,000.00 | 6,600.00 |
| Total cost of change | Cost to actually deliver it | 72,600.00 |
| Markup | 25% of ₹72,600.00 | 18,150.00 |
| Net addition before GST | What you would quote | 90,750.00 |
| GST | 18% of ₹90,750.00 | 16,335.00 |
| Total addition including GST | What the client pays | 1,07,085.00 |
The order of operations, in words
- Effort cost = hours × rate.
- Direct cost = effort cost + other direct costs.
- Contingency = direct cost × contingency %.
- Total cost = direct cost + contingency.
- Markup = total cost × markup %.
- Net addition before GST = total cost + markup.
- GST = net addition × GST rate.
- Total addition including GST = net addition + GST.
The order matters. Marking up the contingency, or applying GST to the whole thing including something that is not taxable, are the two mistakes that quietly inflate a change price. Note also that the GST rate above is the rate that would apply if the change is billed on its own — the rate and the place of supply for your actual supply are for your chartered accountant to confirm.
Scope change cost — illustrative example (CSV) Input,Value Effort hours,48 Hourly or day rate (INR),"1,250.00" Other direct costs (INR),"6,000.00" Contingency (%),10 Markup on cost (%),25 GST rate (%),18 Schedule impact (working days),8 Line,Amount (INR) "Effort cost (48 × 1,250.00)","60,000.00" Direct cost (effort + other),"66,000.00" Contingency at 10%,"6,600.00" Total cost of change,"72,600.00" Markup at 25%,"18,150.00" Net addition before GST,"90,750.00" GST at 18%,"16,335.00" Total addition including GST,"1,07,085.00"
How to use it on a real change
Four steps, in the order that keeps the number defensible.
Break the change into hours, not features
Design, build, QA, handover. Estimate the hours per person and use your real rate. Features are hard to price; hours at a known rate are arithmetic you can check.
Add the costs that are not hours
Third-party licences, materials, a subcontractor, travel, or a rush fee. These sit in the “other direct cost” field, above the markup, because they are not your time and should not be marked up as if they were.
Set contingency for the uncertainty, not out of habit
If the change is well understood, keep contingency low. If nobody can say what it involves yet, keep it higher — and consider pricing the discovery separately before committing to a fixed number.
Copy the figures into the change request
The copy button puts the inputs and every calculated line on your clipboard as CSV, so the change request, the quotation revision, and your own sheet all carry identical numbers.
When to use this, and when to stop
Costing a single change is arithmetic. The moment you want to know whether the project as a whole is worth continuing, you need the record rather than the calculation.
When this template is the right tool
- You quote project work and changes keep arriving as requests rather than as priced items.
- You want the cost of a change separated from your markup, so you can see which part is the work.
- You are still deciding what your rates and contingency policy should be, and this shows the effect of each.
- You need a defensible number to put in front of a client who asked whether it can be done cheaply.
When you have outgrown it
- You accept the change, absorb it, and discover the effect on the project only at the end.
- Different changes are priced by different people with different rules and nobody compares them.
- The cost of a change is agreed verbally, then re-derived later from timesheets.
- You cannot say which kinds of change consistently cost more than you charge for.
The same process in NoxOrigin
The calculator handles one change. NoxOrigin holds every change against the project it belongs to, with quoted value, approved change orders, billed value, and delivered work comparable on the same record — so a project that has quietly absorbed four small changes shows up as a margin problem while it is still running, rather than at the invoice. It does not tell you what to charge; it stops the effect of the charge from being invisible.
- Project profitability calculatorPut quoted value plus approved changes against direct cost and internal hours for the whole project, not just one change.
- Profit margin calculatorCheck the margin you actually end up with on a given price, and convert between markup and margin.
- Project profitability in NoxOriginQuoted against billed value per project, so under-quoted work and unbilled scope become findable.
- Change request templateThe document these figures go into, with the approval decision recorded.
- Quotation templateWhere the approved change is added to the line items and the total.
- Project scope templateThe agreed scope a change has to be measured against.
Scope change cost questions
Where should the hourly rate come from?
From your own numbers: what an hour of that person's time costs you, including the salary, the overheads, and the fact that only part of a working day is billable. The example uses ₹1,250.00 purely as a placeholder. If you do not know your rate yet, work the cost up from an hourly cost and treat the difference as your margin, rather than picking a number that feels competitive.
What is a fair contingency on a change?
Yours, and it depends on how well the change is understood. A change that is a genuine surprise deserves a real risk allowance; a change that has already been scoped and quoted does not need one at all, because the estimate is no longer an estimate. The calculator takes whatever percentage you set and does not suggest a value.
Markup or margin — which should I use here?
A markup is a percentage of cost, so ₹1,00,000 of cost at 25% markup gives ₹1,25,000. A margin is a percentage of the price you charge, so the same ₹1,00,000 of cost at 25% margin needs a price of ₹1,33,333.33. The two are close enough to be confused and far enough apart to cost you money, so decide which one you are quoting in and write the label on the document.
Should the schedule impact change what I charge?
Sometimes, and that is a commercial judgement rather than a calculation. The calculator carries the working days as a field so the change and its cost arrive together, on the same page, instead of cost being discussed on Monday and the date on Tuesday. What a day of delay is worth to you is a decision only you can make.
Does the calculator account for the effect of a delay on the rest of the project?
No, and nothing on this page claims it does. It costs the change itself. If your delivery has a fixed-date penalty, or if the delay displaces other work, that is a separate cost to work out and add deliberately.
Cost every change. Keep them attached to the project.
If the changes are being decided in chat and the effect only appears on the final invoice, that gap is worth mapping.