--- title: "Estimated cost never actual; data required" subject: "Estimating and Costing" chapter: 1 key: "semester_7/estimating_and_costing:est-cost-never-actual-data" source: https://www.bctengineer.com/q/semester_7/estimating_and_costing/est-cost-never-actual-data site: BCT Engineering --- # Estimated cost never actual; data required Estimating and Costing · Chapter 1: Introduction - Asked in: 2078 Bhadra, 3+2 marks - Video: [Part 19 ! Estimating and Costing ! Detailed estimate ! Rough cost estimate ! Types of estimate ! SSC](https://www.youtube.com/watch?v=0vU2E4GznJk) — NARAYANA COACHING CLASSES - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/estimating_and_costing/est-cost-never-actual-data - Whole chapter: https://www.bctengineer.com/md/semester_7/estimating_and_costing/chapter-1 ## Question Explain that estimated cost is never the actual cost. What are the data required for estimating? ## Short answer Estimated cost is a forecast that differs from actual cost due to rate fluctuations, site condition changes, design modifications, and unforeseen events, so a contingency is included. Key data required are drawings, specifications, prevailing rates, site data, and quantities. ## Answer #### Estimated cost is never the actual cost Estimated cost is a forecast made before the work. Actual cost is only known when the work ends. They differ because: - rates of materials, labour and fuel change with time; - site conditions (soil, water table, access) differ from those assumed, changing quantities; - design changes, variation orders and extra items appear; - wastage, productivity and supervision differ from norms; - unforeseen events (weather, strikes, delays) add cost; - measurement and approximation errors exist in the estimate. A contingency of 3 to 5% is added to cover this, but exact equality is not expected. #### Data required for estimating - **Drawings:** plans, elevations, sections, foundation and structural details, and schedules of doors, windows and finishes. Without complete drawings, quantities cannot be taken out. - **Specifications:** the quality of materials and workmanship (for example cement mortar 1:4, M20 concrete, Fe 500 steel), so that the correct rate can be applied. - **Rates:** the District Rate (published yearly by the District Rate Fixation Committee), the DUDBC norms for labour and material consumption, and local market rates for items not covered. Rates of materials, labour, transport (lead), and the contractor's overhead and profit are needed. - **Site data:** site conditions, soil type, water table, distance of material sources (lead), and access. - **Quantities:** the work quantities taken out item by item, using the units of IS 1200 / the Nepal standard methods of measurement. - **Other data:** the applicable taxes (VAT 13%), contingency, price-adjustment and the contract conditions. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Why does actual cost differ from estimated cost? A. Actual cost is a forecast B. Rates, site conditions, design and wastage differ from those assumed C. Estimates ignore drawings D. Contingency is never added Answer: B. The estimate's assumptions change during execution. (Key point: Reason for difference) 2. Why are complete drawings needed as data for an estimate? A. They fix the contractor's profit B. They give the VAT rate C. Without them quantities cannot be taken out D. They are needed only for painting Answer: C. Quantities are taken from drawings. (Key point: Drawings) 3. Why are specifications needed for an estimate? A. They give the site soil type B. They give the District Rate C. They replace the bill of quantities D. They state quality of materials and workmanship so the correct rate can be applied Answer: D. Mortar mix, concrete grade and steel grade decide the rate. (Key point: Specifications) 4. Which item is part of site data? A. Distance of material sources (lead) and soil type B. VAT of 13% C. Mix proportion of mortar D. Format of the BOQ Answer: A. Site data covers soil, water table, lead and access. (Key point: Site data) ## Related in Estimating and Costing - [Estimated cost is never the actual cost](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Aest-cost-never-equal-actual) — Estimating and Costing, chapter 1 - [Purposes of estimating; estimate never actual cost](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Apurposes-estimate-never-actual) — Estimating and Costing, chapter 1 - [Compare estimated cost and actual cost](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Acompare-estimated-actual-cost) — Estimating and Costing, chapter 1 - [Estimating, purpose and data required](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Aestimating-purpose-data-required) — Estimating and Costing, chapter 1, asked 6× - [Estimate, quantity survey, estimated vs actual](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Aestimate-quantity-survey-actual) — Estimating and Costing, chapter 1 - [Data required for detailed estimate](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Adata-for-detailed-estimate) — Estimating and Costing, chapter 1 ## Related in other subjects - [Cost variance analysis from standard and actual](https://www.bctengineer.com/question.md?key=semester_6%2Fengineering_economics%3Acost-variance-analysis-9000-units) — Engineering Economics, chapter 1 - [Cost estimating and types of estimates](https://www.bctengineer.com/question.md?key=semester_7%2Fict_project_management%3Acost-estimating-types) — ICT Project Management, chapter 9 - [Cost estimating tools](https://www.bctengineer.com/question.md?key=semester_7%2Fict_project_management%3Acost-estimating-tools) — ICT Project Management, chapter 9