The difference between the budgeted cost and the actual cost incurred is the most critical indicator of a project's health. A project can look successful on paper — on schedule, no incidents — but if the actual cost exceeds the budget, profitability disappears. This article shows you how to calculate, analyze, and interpret cost variances.
Core Concepts
Budget (sale cost)
This is what you estimated when you won the project. It includes all expected costs plus a profit margin. It is your target.
Example: You budgeted a residential project at €500,000 in cost + €50,000 margin = €550,000 contract value.
Budget breakdown:
|
Item |
Amount |
|
Concrete structure |
150,000 |
|
Envelope and walls |
120,000 |
|
MEP systems |
80,000 |
|
Finishes |
90,000 |
|
Indirect costs |
30,000 |
|
Labor |
30,000 |
|
Total budgeted cost |
500,000 |
|
Margin |
50,000 |
|
Total contract value |
550,000 |
Actual Cost
This is what you actually spent executing the project. It is calculated by summing:
- Material invoices
- Payroll and daily work logs (labor)
- Subcontractor invoices
- Indirect costs allocated to the project
The actual cost is only fully known at the final close of the project (6–12 months after completion).
Variance
This is the difference: Variance = Actual cost – Budget
- If the variance is negative, you are performing better than budgeted (saving)
- If the variance is positive, you are performing worse than budgeted (overrun)
Example: Actual cost €520,000 vs. Budget €500,000 = Variance +€20,000 (cost overrun)
Project Result
This is the profit or loss of the project after all costs.
Result = Contract value – Actual cost
Using the example above:
- Contract value: €550,000
- Actual cost: €520,000
- Result: €30,000 (margin erosion)
Detailed Calculation: A Practical Example
Let's analyze a real renovation project for 60 apartments:
Original budget
|
Trade |
Budget (€) |
|
Structure and foundations |
300,000 |
|
Facade |
200,000 |
|
Partitions and walls |
150,000 |
|
Flooring |
180,000 |
|
Tiling |
120,000 |
|
Painting |
80,000 |
|
Electrical installation |
200,000 |
|
Plumbing installation |
160,000 |
|
HVAC |
250,000 |
|
Metalwork and carpentry |
140,000 |
|
Elevators |
120,000 |
|
Indirect costs |
150,000 |
|
TOTAL |
2,050,000 |
|
Trade |
Budget (€) |
Actual Cost |
Variance |
% |
|
Structure |
300,000 |
320,000 |
+20,000 |
+6.7% |
|
Facade |
200,000 |
210,000 |
+10,000 |
+5.0% |
|
Partitions |
150,000 |
145,000 |
-5,000 |
-3.3% |
|
Flooring |
180,000 |
195,000 |
+15,000 |
+8.3% |
|
Tiling |
120,000 |
130,000 |
+10,000 |
+8.3% |
|
Painting |
80,000 |
78,000 |
-2,000 |
-2.5% |
|
Electrical installation |
200,000 |
240,000 |
+40,000 |
+20.0% |
|
Plumbing installation |
160,000 |
175,000 |
+15,000 |
+9.4% |
|
HVAC |
250,000 |
290,000 |
+40,000 |
+16.0% |
|
Metalwork and carpentry |
140,000 |
140,000 |
0 |
0.0% |
|
Elevators |
120,000 |
210,000 |
0 |
0.0% |
|
Indirect costs |
150,000 |
160,000 |
+10,000 |
+6.7% |
|
TOTAL |
2,050,000 |
2,183,000 |
+133,000 |
+6.5% |
- Contract value: €2,050,000 (without margin for this example)
- Actual cost: €2,183,000
- Result: -€133,000 (loss)
- Actual margin: -6.5% (we expected to make something, we lost instead)
Typical Causes of Variances in Spain
1. Unplanned specification changes
Common case: The client requests "a slight upgrade" to finishes. Tiling budgeted at standard ceramic (€12/m²) is executed in imported ceramic (€25/m²).
In the example: The tiling variance of +8.3% is probably due to this.
Corrective action: Formalize specification changes through a change order with a price increase approved by the client.
2. Discoveries during execution
Common case in renovation: You discover damaged structural elements (rot, damp, decay) that require repair. Or you find archaeological remains that halt work.
In the example: Structure +6.7%, facade +5.0% likely due to unforeseen repair work.
Corrective action: Document discoveries photographically, request an inspection by the client, formalize a change order for the additional cost.
3. Material price increases
Common case: Steel rises 15% between when you estimate and when you buy. Concrete rises 10%. Supply lead times lengthen, causing additional logistics costs.
In the example: It is likely that the overall 6.5% variance includes material price increases.
Corrective action: In future contracts, include a price revision clause indexed to market rates (if steel goes up, it is recognized in billing).
4. Labor inefficiency
Common case: Actual output is lower than budgeted. Instead of 15 m²/day on flooring, you achieve 12 m²/day due to coordination issues, site conditions, etc.
Formula:
- Budgeted: 180,000 m² ÷ 15 m²/day = 12,000 work days
- Actual: 180,000 m² ÷ 12 m²/day = 15,000 work days
- Cost overrun: 3,000 days × €50/day = €150,000 additional
In the example: Flooring +8.3%, tiling +8.3% suggest productivity issues.
Corrective action:
- Analyze what caused the inefficiency (coordination, weather, material availability)
- Reschedule subsequent work
- Change crews or specialists if the pattern is systemic
5. More complex MEP systems than anticipated
Common case: Electrical, plumbing, and HVAC installations are more complex in execution than on the drawings. More pipe runs, more branch connections, repair of existing infrastructure.
In the example: Electrical +20%, HVAC +16%, plumbing +9.4%. These are large variances suggesting underestimated complexity.
Corrective action: Review the MEP design with specialists before estimating. Include a contingency for unknowns (typically 5–10% on renovation projects).
6. Delays and extended indirect costs
Common case: The project is delayed 2–3 months due to rain, client changes, or coordination problems. Indirect costs (technical staff, insurance, equipment rentals) extend accordingly.
If you budgeted 18 months and it actually takes 21 months, those 3 extra months of indirect costs (salaries, technical office expenses) add to the loss.
In the example: Indirect costs +6.7% suggests a time extension.
Corrective action: More realistic scheduling that accounts for risk. Penalty clauses for delays attributable to the client.
7. Theft or loss on site
Common case: Stolen materials, lost tools, damaged equipment. On urban sites with difficult controlled access, this is common.
Corrective action: Site security, locked storage, periodic inventory counts, theft insurance policies.
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Variance Indicators by Trade Type
Some useful analyses:
Variance by cost type
Group variances by type:
|
Cost type |
Budget (€) |
Variance |
Probable cause |
|
Labor |
600,000 |
+80,000 (+13%) |
Inefficiency, delays |
|
Materials |
900,000 |
+40,000 (+4%) |
Inflation, spec changes |
|
Subcontractors |
450,000 |
+10,000 (+2%) |
Better management |
|
Indirect costs |
100,000 |
+3,000 (+3%) |
Normal |
|
TOTAL |
2,050,000 |
+133,000 (+6.5%) |
Cumulative variance vs. budget
Some trades are on track, others are off:
- Trades with variance > 10%: Investigate what happened
- Trades with variance < 2%: They were well estimated
- Trades with negative variance: Executed better than budgeted (rare — verify all costs have actually been allocated)
Reading a Project Results Report
A professional results report includes:
Page 1: Executive summary
- Total budget: €2,050,000
- Actual cost: €2,183,000
- Variance: +€133,000 (+6.5%)
- Result: -€133,000 (if budget with no margin)
- Status: Closed
Page 2: Trade-by-trade comparison (as in the table above)
Allows rapid identification of where variances occurred.
Page 3: Cause analysis
For each trade with variance > 5%, describe the cause:
"Electrical installation +€40,000 (+20%): Design changes requested by client in month 6 (change order no. 5), addition of home automation systems not included in the original design, and greater coordination complexity with other MEP trades. A change order approved by the client for €35,000 was issued."
Page 4: Lessons learned
- What caused the estimating error?
- How will I improve future estimates?
- Are there company processes I need to change?
Managing Variances During Execution
The ideal is NOT to wait until close to identify variances. You must detect them in real time.
Monthly variance tracking
Each month, calculate:
Cumulative variance at month 6:
|
Trade |
Budget (€) |
Cumulative actual cost |
Variance |
Status |
|
Structure |
300,000 |
280,000 |
-20,000 |
✓ Within budget |
|
Facade |
200,000 |
150,000 |
-50,000 |
✓ Within budget (not yet complete) |
|
Electrical installation |
200,000 |
90,000 |
-110,000 |
? Review (still 45% to execute) |
|
HVAC |
250,000 |
-180,000 |
-180,000 |
? Review (still 72% to execute) |
- Renegotiate with the subcontractor
- Request a change order from the client
- Change specifications
- Absorb the cost if the margin allows it
Early warning alerts
Configure alerts in your software:
- If a trade accumulates variance > 10%, investigate the cause
- If committed costs (purchase orders + issued contracts) already exceed the trade budget, halt new purchases
- If the monthly cumulative gap grows > 2%, investigate
Detailed Numerical Example: Variance by Trade
Let's analyze just the "Electrical installation" trade in detail:
Original budget
|
Item |
Quantity |
Unit price |
Amount |
|
VV 6mm² cable |
5,000 m |
€0.80/m |
€4,000 |
|
Conduit |
3,000 m |
€1.20/m |
€3,600 |
|
Distribution panels |
12 units |
€800/unit |
€9,600 |
|
LED light points |
180 units |
€40/unit |
€7,200 |
|
Outlets and sockets |
200 units |
€15/unit |
€3,000 |
|
Electrician labor |
500 h |
€50/h |
€25,000 |
|
Helper labor |
300 h |
€25/h |
€7,500 |
|
Small materials |
lump sum |
— |
€140,100 |
|
TOTAL |
€200,000 |
Actual execution
|
Item |
Quantity |
Actual unit price |
Actual amount |
|
VV 6mm² cable |
5,500 m |
€1.00/m |
€5,500 |
|
Conduit |
3,200 m |
€1.40/m |
€4,480 |
|
Distribution panels |
14 units |
€900/unit |
€12,600 |
|
LED light points |
200 units |
€50/unit |
€10,000 |
|
Outlets and sockets |
220 units |
€18/unit |
€3,960 |
|
Electrician labor |
650 h |
€55/h |
€35,750 |
|
Helper labor |
400 h |
€28/h |
€11,200 |
|
Small materials |
lump sum |
— |
€156,510 |
|
ACTUAL TOTAL |
€240,000 |
|
Item |
Budget |
Actual |
Variance |
Cause |
|
Cable |
4,000 |
€5,500 |
+1,500 |
Greater quantity (additional circuits), material inflation |
|
Conduit |
3,600 |
4,480 |
+880 |
Greater quantity, price increase |
|
Panels |
9,600 |
12,600 |
+3,000 |
Greater quantity (2 additional panels for extra circuits), higher price |
|
LED light points |
7,200 |
10,000 |
+2,800 |
Greater quantity (20 additional points), higher price (premium LED) |
|
Outlets |
3,000 |
3,960 |
+960 |
Greater quantity, higher price |
|
Electrician labor |
25,000 |
35,750 |
+10,750 |
Greater hours (+150h, +30%), higher hourly rate (+10%) |
|
Helper labor |
7,500 |
11,200 |
+3,700 |
Greater hours (+100h, +33%) |
|
Small materials |
140,100 |
156,510 |
+16,410 |
Proportional to greater scope |
|
TOTAL |
200,000 |
240,000 |
+40,000 |
1. Specification changes (+€10,000): Client requested premium LED light points instead of standard, and additional circuits. Approved in change order no. 5.
2. Greater measured scope (+€8,000): Cable and conduit required more length than measured on the drawings. Complexity routing installations through the existing facade.
3. Price inflation (+€12,000): Cable went from €0.80 to €1.00/m (+25%), conduit from €1.20 to €1.40/m (+17%), panels from €800 to €900/unit (+12.5%).
4. Labor inefficiency (+€10,000): Output was below what was budgeted. We estimated 500 electrician hours. In reality it was 650 hours. This suggests:
- Coordination with other MEP trades
- Repair of damaged existing infrastructure
- Waiting for material deliveries
- Access difficulties in the renovation context
How Trowel Helps with Variance Analysis
Trowel integrates the full variance analysis cycle:
Budget vs. actual comparison in real time:
- Every invoice is allocated to the corresponding budget line
- Every daily work log (labor) is assigned to a trade
- Automatic monthly comparison without waiting for close
Detailed breakdowns:
- By budget trade
- By cost type (labor, materials, subcontractors)
- By supplier
- By time period (month, quarter)
Variance analysis:
- Automatic calculation of variances and percentages
- Alerts when variance exceeds a configured threshold
- Trend analysis (is it getting better or worse?)
Indicators:
- CPI (Cost Performance Index)
- Forecast at completion (projected final cost based on current variance)
- Profitability impact (cumulative loss vs. margin budget)
Documentation:
- Link between variance and cause (change order, specification change, etc.)
- History of changes and variations
- Full traceability for lessons-learned analysis
Executive reports:
- Automatic project results report
- Multi-project comparison (why did one project deviate 2% and another 15%?)
- Analysis of "what went well, what went wrong"
With Trowel, you identify variances instantly — not at project close. You have time to act.
Request a demo and see how other Spanish contractors track their variances in real time.
