Detailed Estimate

A detailed estimate is the accurate, item-by-item cost of a project, prepared from complete drawings and specifications. It is the basis for administrative sanction, tendering and cost control, and is far more reliable than a preliminary (approximate) estimate.

The process is: measure the quantity of each item (taking off), price each by its analysed rate, and sum them in the abstract of estimate. To this are added percentages for contingencies (unforeseen items, 3–5%) and work-charged establishment (site supervision staff).

During execution, a revised estimate is prepared if the cost is likely to exceed the sanctioned amount materially (e.g. beyond 5%), and a supplementary estimate covers additional works not in the original scope, keeping the financial sanction in step with the actual work.

Relation 1 —

Write this relation with symbols exactly as in Estimating & Costing — BN Dutta before substituting numbers. Examiners award partial marks for a correct setup even when arithmetic slips.

Relation 2 —

Write this relation with symbols exactly as in Estimating & Costing — BN Dutta before substituting numbers. Examiners award partial marks for a correct setup even when arithmetic slips.

Relation 3 —

Write this relation with symbols exactly as in Estimating & Costing — BN Dutta before substituting numbers. Examiners award partial marks for a correct setup even when arithmetic slips.

The detailed estimate contrasts with approximate estimates (plinth-area, cubic-content, unit-rate) used at the planning stage; while approximate methods give a quick figure per unit area or per functional unit, the detailed estimate measures actual quantities and is used for sanction and execution.

The abstract of estimate lists every item with its quantity, unit, rate and amount, and the sum gives the works cost; the sequence measurement → abstract → report ensures traceability from drawing to cost.

Contingencies allow for minor unforeseen items and small quantity variations, while the work-charged establishment covers the cost of temporary supervisory staff engaged specifically for the project; both are added as percentages of the works cost.

Revised and supplementary estimates maintain financial discipline: a revised estimate re-sanctions the project when the original is likely to be exceeded, and a supplementary estimate covers genuinely new items, so that expenditure always has valid sanction — a key requirement in public works accounting.

State assumptions explicitly before using any relation for detailed estimate — steady state, uniform properties, linear elastic material, ideal gas, incompressible flow, etc., as applicable.

Wrong assumptions invalidate the entire solution even when the formula is correct. In Estimation & Costing viva and GATE descriptive questions, listing valid assumptions often earns separate marks.

1. Read the question and list given data with SI units (common in Estimation & Costing papers).
2. Draw a neat labelled diagram where applicable — examiners in Indian universities award diagram marks even when arithmetic slips.
3. Identify which relation from this topic applies to detailed estimate.
4. Use equation 1: .
5. Use equation 2: .
6. Substitute values, compute, and verify units and sign (direction).
7. State conclusion in one line — e.g. safe/unsafe, stable/unstable, feasible/infeasible.

Detailed Estimate appears in tendering and project billing. In Indian civil curricula this topic is tested because it connects theory to quantity surveying and valuation.

GATE and semester exams often combine detailed estimate with earlier units — revise prerequisites before attempting mixed problems.

Industry interview panels sometimes ask: "Where did you use detailed estimate?" — answer with a lab, mini-project, or plant visit example if possible.

• Confusing a detailed estimate with an approximate (plinth-area) estimate.
• Omitting contingencies and establishment charges from the total.
• Failing to prepare a revised estimate when the cost overruns significantly.
• Not following the measurement → abstract → report sequence.

Before attempting detailed estimate problems, confirm you can:

1. Detailed estimate includes plan, sections, specifications
2. Revised estimate when scope increases beyond 5%
3. Supplementary estimate for additional items during execution

Revise the solved examples in Estimating & Costing — BN Dutta and one previous-year GATE or university paper for this unit.