Why project estimates go wrong
Ask a project shop why a job lost money and you will usually hear the same thing: “the estimate was optimistic.” But an estimate is rarely wrong because someone was hopeful — it is wrong because it was never built from structure. A single lump-sum guess, or a materials list with a flat percentage bolted on for “labour and overheads,” has no way to be checked, no line to argue about, and no way to compare against what actually happens. When the job overruns, nobody can say which part was underestimated.
Disciplined estimation flips that. Instead of one number, you build the estimate bottom-up from the Work Breakdown Structure: every task carries a Bill of Resources, every resource line is a quantity times a rate, and the project estimate is simply those lines rolled up. Now the estimate is a document, not a hunch — every rupee traces to a task and a resource, so it can be reviewed before you quote and checked against reality after you win.
The bottom-up method in six steps
The method is the same whether you fabricate skids, erect a plant or build a special-purpose machine. Six steps take you from a blank project to a defensible number.
Two of these steps do the heavy lifting. Step 2 — building each task’s BOR — is where you decide what the work actually takes, and it is the step generic tools cannot do because they have no resource lines. Step 3 — pricing from a resource master — is what keeps the estimate consistent: a welder-hour or a crane-day is priced the same across every project, and when a rate changes you re-cost every open estimate rather than editing spreadsheets one by one.
A worked example in INR
Consider a fabrication shop quoting four steel skid frames. The project is broken into five costable tasks. Each has a BOR; here are the rolled-up task costs.
| Task | Main resources | Estimated cost (INR) |
|---|---|---|
| Design & drawings | Design engineer hours | ₹ 45,000 |
| Cutting | Plate, gas cutting machine, operator | ₹ 1,80,000 |
| Welding | Wire, gas, welder & helper, welding set | ₹ 2,40,000 |
| Assembly & fit-up | Fitter hours, consumables, crane time | ₹ 1,30,000 |
| Testing & dispatch | NDT, paint, packing, transport | ₹ 85,000 |
| Estimated project cost | Roll-up of all tasks | ₹ 6,80,000 |
Each figure is not typed in — it is a roll-up of quantity × rate lines. The welding task’s ₹2,40,000, for example, is welding wire and gas at their item rates, plus welder and helper man-hours at their labour rates, plus welding-set machine-hours at its machine rate. Because the numbers are built this way, you can drill into any task to see why it costs what it does, and a BOR-cost breakdown shows which resource dominates — here, labour and the welding set. Add your margin to the ₹6,80,000 and you have a quote you can defend line by line. These figures are illustrative; use your own rates and confirm treatment with your CA.
Turn your next quote into a bottom-up estimate
We can build one of your live jobs as a WBS with per-task Bills of Resources, rolled up to a project estimate against budget, in a 30-minute demo.
Estimate vs budget — reading the gap
An estimate has a companion number: the budget. The budget is what you committed to — the value in the contract, or the figure the customer will bear. The estimate is what your bottom-up roll-up says the work will actually cost. Reading the gap between them, before you quote, is the whole point of estimating.
If the estimate sits comfortably below budget, you have margin. If it is level or above, you have a decision — re-scope, re-source, renegotiate, or walk — and you are making it now, with a line-item view of where the money is, rather than at the year-end post-mortem. Each project and each task carries both a budget and, as work proceeds, an actual, so the estimate you build today becomes the baseline you track against tomorrow. That live comparison is covered in the sibling guide on budget vs actual tracking.
Common estimating pitfalls
- Costing material and forgetting machines. The plant and equipment a task runs — cranes, welding sets, machining centres — are often the biggest lines, and a materials-only estimate misses them entirely. A Bill of Resources includes them by design.
- Flat labour percentages. Adding “30% for labour” on top of material is a guess dressed as a method. Estimate labour as man-hours at a rate, task by task.
- Stale rates. If rates live in an old spreadsheet, every estimate is priced on last year’s costs. A single resource master keeps rates current everywhere.
- No link to actuals. An estimate you never compare against real consumption teaches you nothing. Keep the estimate keyed to the tasks so actuals post against it.
How Fast Project Software estimates cost
Fast Project Software implements exactly this bottom-up method. You break a project into a WBS, build a Bill of Resources per task from the shared resource master, and cost estimation rolls quantity × rate up to a task and project cost with a BOR-cost breakdown by resource. Each project and task holds a budget alongside the estimate, so the gap is visible before you quote and the estimate becomes the baseline for tracking. Because it all rides one engine keyed to the project and task, the same numbers flow on to material issue and milestone billing — nothing re-keyed at a boundary. It suits ETO manufacturers, fabrication shops and EPC firms; pricing is indicative and in INR, so see pricing and confirm figures with your CA.
Frequently asked questions
How do you estimate the cost of a project?
Estimate a project bottom-up: break the deliverable into a Work Breakdown Structure of tasks, build a Bill of Resources for each task listing the material, labour and machine it consumes, price each line from a resource master, multiply quantity by rate for every line, and roll the line costs up to a task cost and then to a whole-project estimate. Finally, compare that estimate against the project budget. This gives an estimate you can take apart line by line rather than a single lump-sum guess.
What is the difference between an estimate and a budget?
The estimate is what your bottom-up roll-up says the work will actually cost — the sum of quantity times rate across every resource line. The budget is what you committed to: the contract value or the figure the customer will bear. A project business is run in the gap between them. Reading that gap before you quote lets you re-scope, re-source or renegotiate while you still can, instead of discovering the shortfall after the work is done.
Why estimate from a Bill of Resources rather than a lump sum?
A lump-sum estimate cannot be checked, argued about or tracked, because nothing links the number to the work. Estimating from a per-task Bill of Resources gives every rupee a line — a specific material, labour or machine resource on a specific task — so the estimate can be reviewed before quoting and compared against real consumption after winning. It also captures machine and labour costs that a materials-only estimate misses entirely.
How does the resource master keep estimates accurate?
A resource master holds each machine, labour category and tool once, with its rate, working hours and efficiency. Every Bill of Resources pulls its rates from that master, so a welder-hour or a crane-day is priced the same across every project. When a rate changes, you update it once and re-cost every open estimate, rather than editing rates in dozens of separate spreadsheets and hoping they all match.
Can the estimate be tracked against actual cost later?
Yes. Because the estimate is keyed to the project and its tasks, real consumption posts against the same structure as work proceeds: material issued from stores against a task, and labour and machine time booked to it, become actual cost sitting next to the estimate. Each project and task carries both a budget and an actual, so the estimate you build today becomes the baseline you track estimated-versus-actual against tomorrow.