---
title: "Triple constraints of a project"
subject: "ICT Project Management"
chapter: 1
key: "semester_7/ict_project_management:triple-constraints"
source: https://www.bctengineer.com/q/semester_7/ict_project_management/triple-constraints
site: BCT Engineering
---

# Triple constraints of a project

ICT Project Management · Chapter 1: Introduction

- Asked in: year not given
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_7/ict_project_management/triple-constraints
- Whole chapter: https://www.bctengineer.com/md/semester_7/ict_project_management/chapter-1

## Question

Explain the triple constraints of a project.

## Short answer

The triple constraint (iron triangle) limits every project by three linked factors: scope, time, and cost. Changing one forces a change in another, and quality depends on how well they are balanced. A project manager must evaluate every change against all three constraints.

## Answer

The **triple constraint** (iron triangle) says that every project is limited by three linked factors: **scope, time and cost**. Quality depends on how well these three are balanced. Changing one usually forces a change in another.

```text
              SCOPE
               /\
              /  \
             / Q  \
            /______\
          TIME     COST
```

#### The three constraints
- **Scope**: the work needed to deliver the product or service, with all its features and requirements. Question: what work will be done?
- **Time**: the schedule, i.e. how long the work will take and when it must finish. Question: how long will it take?
- **Cost**: the budget, based on resources, labour, equipment and materials. Question: how much will it cost?

#### Relationship between them
- If the customer adds features (scope increases), either the deadline moves out (time) or more people are needed (cost).
- If the deadline is shortened, either scope must be cut or extra cost (crashing, overtime) is needed.
- If the budget is cut, scope or schedule must give way, and quality can suffer.

#### Example
A college wants a student information system. If, after planning, the college asks for an extra online fee payment module, the developer needs more programmers (cost) or more weeks (time).

#### Use for the project manager
- Decide which constraint is most flexible and which is fixed.
- Evaluate every change request against all three.
- Schwalbe adds that a good project manager also considers quality, risk and customer satisfaction, since meeting only the three constraints does not guarantee success.

Modern PMBOK also considers further constraints such as quality, risk and resources, but the triple constraint remains the basic model.

## Check yourself

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

1. The triple constraint (iron triangle) consists of:
   A. Scope, time and cost
   B. Quality, risk and people
   C. Time, cost and profit
   D. Scope, quality and risk
   Answer: A. The three linked constraints are scope, time and cost; quality depends on how well they are balanced. (Key point: The three constraints)

2. If the customer adds features after planning, what usually must happen?
   A. Nothing changes, because scope is independent
   B. Quality automatically improves
   C. Only the cost falls
   D. The deadline moves out or more resources (cost) are needed
   Answer: D. Changing one constraint forces a change in another, so more scope means more time or cost. (Key point: Scope increase effect)

3. If the deadline is shortened, which response is consistent with the triple constraint?
   A. Cut scope or accept extra cost such as crashing or overtime
   B. Increase scope to compensate
   C. Reduce cost and keep scope unchanged
   D. Ignore quality
   Answer: A. A shorter schedule needs reduced scope or added cost like crashing and overtime. (Key point: Shortened deadline)

4. Why does Schwalbe say meeting only the three constraints is not enough?
   A. Because the constraints are never measurable
   B. Because success also depends on quality, risk and customer satisfaction
   C. Because only cost matters in practice
   D. Because the triangle is obsolete and ignored
   Answer: B. A project can meet scope, time and cost yet still fail to satisfy the customer or manage risk and quality. (Key point: Beyond triple constraint)