A work item’s weight (bobot) is its share of the whole project’s value, as a percentage. Weights combine the progress of very different work into one project progress figure: finishing the roof does not mean the same as finishing site preparation, because they are worth different amounts.
The weight formula
Weight = value of the work item ÷ total value of all work × 100%. Values come from the budget (RAB): quantity × unit price. The weights of all work items always add up to 100%.
- Preparation 2%
- Foundations 12%
- Concrete structure 25%
- Walls 15%
- Roof 13%
- Floors 10%
- Finishing 15%
- Electrical and plumbing 8%
Example: a house with a Rp500 million budget
| Work item | Budget value | Weight |
|---|---|---|
| Preparation | Rp10 m | 2% |
| Foundations | Rp60 m | 12% |
| Concrete structure | Rp125 m | 25% |
| Walls | Rp75 m | 15% |
| Roof | Rp65 m | 13% |
| Floors | Rp50 m | 10% |
| Finishing | Rp75 m | 15% |
| Electrical and plumbing | Rp40 m | 8% |
| Total | Rp500 m | 100% |
For example, the concrete structure’s weight = 125 ÷ 500 × 100% = 25%.
Using weights for project progress
Project progress = the sum of (weight × progress) over all work items. For example, preparation 100% done, foundations 100%, structure 60%, walls 20%, the rest not started:
| Work item | Weight | Progress | Weight × progress |
|---|---|---|---|
| Preparation | 2% | 100% | 2.0% |
| Foundations | 12% | 100% | 12.0% |
| Concrete structure | 25% | 60% | 15.0% |
| Walls | 15% | 20% | 3.0% |
| Others | 46% | 0% | 0.0% |
| Project progress | 32.0% |
For the S-curve, each item’s weight is spread over the weeks it runs. A 25% concrete structure built over 5 weeks plans 5% a week.
VAT, lump-sum items and addenda
- If VAT applies evenly to every item, weights are the same with or without it. Weights are usually worked out from values before VAT.
- Lump-sum items such as mobilisation get a weight from their value, and their progress is judged by agreed stages, for example 50% when equipment arrives and 100% when ready to work.
- After an addendum, work out new weights from the new total, carry over the progress already made, and keep the old S-curve as a baseline.
How to calculate weights in Excel
- Make sure each work item has a value: quantity × unit price, for example in column E.
- Add the total below, for example =SUM(E5:E12) in cell E13.
- In the weight column enter =E5/$E$13 and copy it down. The $ signs keep the total cell fixed.
- Format the weight column as a percentage and check the total: =SUM(F5:F12) must be 100%.
Common mistakes
- Weights taken from quantities instead of value. 100 m2 of paint and 100 m2 of tiles do not weigh the same.
- Only materials or only labour used, so labour-heavy or material-heavy work gets too small a weight.
- Weights that do not add up to 100% because subtotal or section rows were counted too.
- Variation orders (VO) added without recalculating weights. When the contract value changes, recalculate every weight with the new total, or keep VOs separate and say which way you use.
- Weights changed mid-project without a note, so this week’s progress cannot be compared with last week’s.
The full guide is in How to create a weekly construction schedule report in Google Sheets. It has a free template (Excel or Google Sheets) and a checker that reads your own workbook.
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Common questions
What is a work item weight (bobot)?
The share of a work item’s value in the whole project’s value, as a percentage. All weights add up to 100%.
What is the formula for weight?
Value of the work item divided by the total project value, times 100%. Rp125 million out of Rp500 million is 25%.
How do I work out project progress from weights?
Multiply each item’s weight by its progress and add them up. A 25% structure that is 60% done adds 15% to project progress.
Is weight calculated from quantities?
No. Weight comes from value (quantity × unit price), because quantities of different kinds of work cannot be compared.
References
- Permen PUPR No. 8 of 2023 (JDIH PUPR, Indonesian): where the budget values behind weights come from
- Ten Six: Performance % Complete in P6: cost-weighted progress