---
title: "Estimate, quantity survey, estimated vs actual"
subject: "Estimating and Costing"
chapter: 1
key: "semester_7/estimating_and_costing:estimate-quantity-survey-actual"
source: https://www.bctengineer.com/q/semester_7/estimating_and_costing/estimate-quantity-survey-actual
site: BCT Engineering
---

# Estimate, quantity survey, estimated vs actual

Estimating and Costing · Chapter 1: Introduction

- Asked in: 2067 Asar (old course), 3 marks
- Video: [Construction Estimations and Costing - Basic Concept (QS Quantity Surveyor vs. Billing Engineer)](https://www.youtube.com/watch?v=Ko9Gyv0WLXE) — Factual Civil Engineering
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/estimating_and_costing/estimate-quantity-survey-actual
- Whole chapter: https://www.bctengineer.com/md/semester_7/estimating_and_costing/chapter-1

## Question

What is an estimate? What is meant by quantity survey? Distinguish between estimated and actual cost.

## Short answer

An estimate is a forecast of probable quantities and cost before construction. A quantity survey measures work items from drawings to prepare a bill of quantities. Estimated cost is approximate and used for planning, while actual cost is the exact expenditure recorded after completion.

## Answer

#### Estimate
An estimate is the calculation of the probable quantities and cost of a work before construction, based on the drawings, specifications and current rates.

#### Quantity survey
Quantity survey (quantity surveying) is the process of measuring and calculating the quantities of the different items of work and materials from the drawings, and arranging them in a bill of quantities. It is the first step of estimating. It is also used later to measure the completed work for payment.

#### Estimated cost versus actual cost
| Estimated cost | Actual cost |
|---|---|
| Probable cost calculated before execution | Real cost incurred after execution |
| Based on drawings, norms and current rates | Based on bills, vouchers and measurements |
| Approximate; has contingency | Exact and final |
| Used for approval, budget, tendering | Used for final payment and records |
| Can be revised before or during work | Cannot be changed |

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is quantity survey?
   A. Surveying land boundaries only
   B. Fixing rates of labour
   C. Paying the contractor
   D. Measuring and calculating item quantities from drawings and arranging them in a bill of quantities
   Answer: D. It is the first step of estimating and is also used to measure completed work. (Key point: Quantity survey)

2. An estimate is based on
   A. Drawings, specifications and current rates
   B. Bills and vouchers
   C. Final account
   D. Measurement book of completed work
   Answer: A. Bills and vouchers are for actual cost. (Key point: Estimate definition)

3. Which is true of actual cost?
   A. It has a contingency allowance
   B. It is exact and final, used for final payment
   C. It is approximate
   D. It can be revised before work
   Answer: B. Actual cost is the real cost incurred and cannot be changed. (Key point: Estimated vs actual)

## 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
- [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
- [Estimated cost never actual; data required](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Aest-cost-never-actual-data) — 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
- [Method of quantity estimate for road](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Aroad-method-quantity-explain) — Estimating and Costing, chapter 6
- [Components of complete estimate; abstract cost](https://www.bctengineer.com/question.md?key=semester_7%2Festimating_and_costing%3Acomponents-complete-estimate-abstract) — Estimating and Costing, chapter 2

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- [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
- [Socio-economic survey and social cost benefit analysis](https://www.bctengineer.com/question.md?key=semester_7%2Fproject_engineering%3Asocio-economic-survey-scba) — Project Engineering, chapter 2, asked 3×
- [Constant vs actual dollar; inflation-free rate on loan](https://www.bctengineer.com/question.md?key=semester_6%2Fengineering_economics%3Aconstant-actual-dollar-bike-loan) — Engineering Economics, chapter 8, asked 2×
- [Merits of functions; actual vs formal parameters](https://www.bctengineer.com/question.md?key=semester_1%2Fcomputer_programming%3Audf-merits-demerits-parameters) — Computer Programming, chapter 6