ESTIMATION

Detailed Estimate

Quantity-based estimate from drawings. Each work item × unit rate × quantity = cost. ±5% accuracy.

Also calleditem-rate estimateboq estimate
Definition

A detailed estimate (also called item-rate estimate or BOQ estimate) is a project cost estimate prepared at design or tender stage, based on actual quantities calculated from drawings and BOQ items. Used as the basis for tendering, contractor pricing, and budget commitment. The Indian Standard reference: CPWD Manual + DSR (Delhi Schedule of Rates) + state PWD procedures. Detailed estimates have ±5% accuracy and form the basis of contractually-binding BOQ pricing.

Methodology: (1) Drawings — structural, architectural, MEP, finishing — are reviewed comprehensively; (2) Quantity Take-off — every BOQ item's quantity is calculated by formula or measurement: concrete in m³, steel in kg, plastering in m², doors and windows in numbers; (3) Rate Analysis — for each BOQ item, the unit rate is computed from material + labour + plant + overhead + profit; (4) Multiplication — quantity × rate = item cost; (5) Summation — all item costs aggregated to total direct cost; (6) Indirect Costs — site office, supervision, insurance, contingency added; (7) Total — sum of direct + indirect = project cost. For a typical residential project, this typically takes 200-500 person-hours of QS effort.

Indian detailed estimate practice: (a) Government / PSU — strictly per CPWD Analysis with DSR rates. (b) Private commercial — per project specification, often using bespoke rates and modern construction methods. (c) Smaller residential — abbreviated detailed estimates with focus on major items (concrete, steel, masonry, finishes). The most-overlooked aspect: cross-check between BOQ items and actual constructed quantities at the running bill stage. Variation > 10% in any major item indicates either mistakes in quantity take-off, scope creep, or site-specific deviations. Major Indian project software for detailed estimate preparation: Sage Estimating, ProEst, Buildxact, Indian-specific tools (CivilLane, Estimator+), and Excel-based templates. Modern Indian practice increasingly uses BIM-based quantity take-off (Revit Quantification, AutoCAD Quantity Survey) for major projects.

Where used
  • Tendering — basis for contractor priced bid
  • Contract pricing — basis for BOQ amount agreed
  • Running bill reconciliation — checking actual installed vs BOQ
  • Final settlement — variance analysis vs detailed estimate
  • Cost forecasting and budgeting
Acceptance / threshold
Per CPWD + DSR + project specification: every BOQ item with quantity and rate; quantities calculated from drawings; rates from validated source (DSR, state SOR, market); cross-checked by independent QS for major items.
Site example
Site reality: a Pune commercial project's detailed estimate was prepared by a junior QS who used DSR Delhi rates instead of Pune local rates. The estimate was 18% under actual market prices. Discovered at tender response stage when no contractor bid below the estimate. Re-estimated using local rates; tender re-issued. ₹28 lakh re-estimation cost; 6-week schedule slip. Always use locality-specific rates; cross-checking by senior QS prevents 80% of pricing errors.
Frequently asked
What is detailed estimate?
A detailed estimate is a project cost estimate based on actual quantities calculated from drawings and BOQ items, with rate analysis for each item. Used as the basis for tendering, contractor pricing, and contract commitment. ±5% accuracy. CPWD Manual + DSR + state PWD procedures are the Indian standard references.
How is detailed estimate prepared?
(1) Review drawings comprehensively. (2) Calculate quantities for every BOQ item. (3) Compute rate for each item from material + labour + plant + overhead + profit. (4) Multiply quantity × rate = item cost. (5) Sum all item costs = direct cost. (6) Add indirect costs (site office, contingency, etc.). (7) Total = project cost. Cross-check by independent QS for major items.
Why is detailed estimate more accurate than abstract?
Detailed estimate is based on actual quantities from drawings and item-by-item rate analysis — accounting for specific materials, methods, location, and scope. Abstract estimate uses simplified per-area or per-bed rates that average over many projects. Detailed has ±5% accuracy; abstract has ±10-25%. Detailed is essential for tendering and contracts; abstract is appropriate only for concept-stage decisions.
Related estimation terms
Construction Cost Estimation
Per sqft cost ₹1500-3500 in India
Quantity Estimation
Estimate cement, steel, sand, aggregate for given area
Material Wastage Factors
Cement 2-3%, steel 3-5%, tiles 5-10% typical
Bill of Quantities (BOQ)
Itemised list of work activities with quantities and unit rates — forms the priced contract document.
Rate Analysis
Computation of unit rate from material + labour + plant + overhead + profit. Reference: DSR, state SOR, in-house DB.
Abstract Estimate
Cost estimate at concept stage based on plinth area or per-bed/per-room rates. ±20% accuracy.
Contingency
Provision for unforeseen costs. CPWD: 3%. Private: 5-10%. Higher for renovation than new build.