Post-calculation: the key to better margins in future projects
Created December 2025, Reading time: approx. 2-3 minutes
Why post-calculation is the industry's forgotten gold mine
Many construction companies work hard, deliver quality and stand up for their customers – but still struggle with low or unstable margins. In a hectic everyday life, projects are closed, people are sent on to the next assignment, and the most important learning moment disappears: the evaluation of what actually happened. That is precisely why the post-costing is one of the most powerful, but often most underestimated, tools in the entire costing and management process.
A good cost estimate is not about “finding faults” or pointing scapegoats. It is about understanding the reality of the project – so that you can calculate smarter, plan better and increase the profitability of future projects. Cost estimates are simply the link between practice and strategy, between experience and improvement.
In this support article, we delve deeper into why post-calculations are crucial, how they are implemented in practice, what typical deviations occur in the industry – and how digital tools can make the entire process both easier and more valuable.
Part 1: What a post-calculation really is – and why it matters so much
The formal definition is simple: A post-calculation compares the original preliminary estimate with the actual figures in a completed project. But in practice, the post-calculation is much more than a calculation. It is a diagnosis of the quality of the calculation , project management and implementation.
Three main goals with post-calculation:
Uncovering discrepancies
Where did it go as planned – and where did it fall apart?Understand the reasons behind the numbers
Why did an activity take 40% longer? Why was the material consumption higher? Why was there an additional charge from UE?Improve your next project
The figures from the post-calculation are the basis for better calculations , better risk management, more precise quantities and safer margins.
Companies that do this systematically see that the cost estimate has a direct effect on both profitability and competitiveness.
Part 2: How to carry out a post-calculation – step by step
1. Start with original calculation
This is the basis for the comparison. You need to retrieve:
calculation and offer
contracts and EU agreements
any change notifications
quantity descriptions and drawings
This is the outcome of how you thought the project would go.
2. Record actual hourly consumption
Timers are the most common source of error – and often the biggest. Here you should analyze:
total number of hours
hours per activity
waiting, interruptions, incorrect orders
coordination between disciplines
If you systematically see that certain activities consistently take more time, this must be included in the experience figures.
3. Record actual material consumption
Materials often vary by 5–12%, especially when:
competition and waste
adjustments and adaptations on site
extra deliveries
small materials that are “not in the calculation”
Material costs are not just about quantity – but about the quality of logistics and planning.
4. Record UE costs
Many fall here. You must bring:
addition from reservation
costs due to changes
invoices for time spent in case of delays
additional mobilizations
UE costs are often more dynamic than in-house production – and must be analyzed carefully.
5. Record indirect costs
This is the item that is often “forgotten,” and thus eats up margins without anyone noticing.
Typical indirect costs:
transportation and car
project manager hours
administration
tool wear
rigging and operation
construction current
For many entrepreneurs, this is an eye-opener.
6. Compare cost price and selling price
Here comes the truth. Did you get the profit you calculated? Or was the margin eaten up by small deviations throughout the project?
It is important to see both:
total deviation
deviation per activity
variance per cost group
The more detailed you compare, the more precise your experience figures will be.
7. Analyze the deviations
This is the core of learning.
Some questions you should ask:
Why did the hours crack?
Was the work described correctly?
Was the choice of materials optimal?
Was the EU well coordinated enough?
Were the quantities too weakly founded?
Did we have enough time for planning?
Without causal analysis, the post-calculation becomes just a summary, not an improvement tool.
8. Document the learning points
The experience must include:
spreadsheet templates
experience figures
checklists
routines
internal knowledge sharing
If experience is not stored, retrospective calculations have little value.
Part 3: Typical findings in post-calculations – the industry's most common mistakes
When contractors start doing post-costing systematically, the same patterns emerge:
1. Hours are underestimated by 10-25%
Causes:
optimistic estimates
poor coordination
waiting for other subjects
inaccurate quantities
2. Material consumption increases by 5–12%
Causes:
cut, shrinkage and adaptation
wrong orders
projects that change along the way
3. Rig and operation are underestimated
This applies in particular to:
longer construction time than planned
more logistics than expected
more crews on site
4. Small costs are forgotten
Examples:
tool wear
plastic, screws, fasteners
extra trips to the wholesaler
This seems small, but eats up margins quickly.
5. UE costs are often higher than expected
Especially when:
The mission is poorly described.
dependencies change
coordination fails
Part 4: The profitability effect – why post-costing improves margins
Companies that systematically perform post-calculations typically experience:
1. More precise calculations
Each new calculation is based on real experience.
2. Safer risk premium
No more “gut feeling” – but real data.
3. Better management of UE
You see who delivers – and who doesn't.
4. More accurate pricing of jobs
You choose the right projects and avoid losers.
5. Better project management
Deviations are caught earlier next time.
Part 5: Digital tools – when post-calculation becomes easy
In Excel, post-calculations are perceived as time-consuming, and therefore they are often postponed.
Digital calculation tools make the post-calculation much easier by:
retrieve hours automatically
link material costs to the calculation
show deviations directly at record level
save history that can be used in the next project
When the process becomes easy, it gets done – and learning becomes a natural part of the project.
A post-cost estimate is one of the most effective methods for increasing the profitability of construction projects. It provides insight, experience and concrete learning – and makes the next project more precise, safer and more profitable.
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