Understanding the topic
A project estimate combines quantities, unit prices and other costs such as delivery or tool hire. Estimates are approximate and should include a reasonable allowance for waste and unexpected work.
Use the examples below as a starting point, then adapt the method to your own situation.
Step-by-step approach
Measure the job; calculate materials; check pack sizes; add delivery and consumables; include contingency; compare with the budget.
- Identify the purpose and information you need.
- Follow the recommended method carefully.
- Check your result against the original purpose.
- Revise anything unclear or incomplete.
Examples at a glance
| Situation | Example | Explanation |
|---|---|---|
| Paint | Need 7 L; paint sold in 4 L tins. | Buy two tins for 8 L, subject to coverage and coats. |
| Tiles | Floor is 12 m²; allow 10% extra. | Plan for about 13.2 m² before rounding to pack quantities. |
| Materials | Timber $85, fasteners $18, delivery $25. | Subtotal is $128 before contingency. |
| Contingency | Estimated job cost $400; allow 15%. | Contingency $60; planning total $460. |
Four worked examples
Example 1: Paint
Starting point: Need 7 L; paint sold in 4 L tins.
Example 2: Tiles
Starting point: Floor is 12 m²; allow 10% extra.
Example 3: Materials
Starting point: Timber $85, fasteners $18, delivery $25.
Example 4: Contingency
Starting point: Estimated job cost $400; allow 15%.
Common mistakes
- Ignoring pack sizes or minimum order quantities.
- Using measurements from memory rather than checking.
- Forgetting taxes, delivery or waste allowances.
Practice questions
Think about your answer, then expand each question to compare.
Question 1: What is the main purpose of estimating small project costs?
A project estimate combines quantities, unit prices and other costs such as delivery or tool hire. Estimates are approximate and should include a reasonable allowance for waste and unexpected work.
Question 2: What is a useful first step?
Measure the job; calculate materials; check pack sizes; add delivery and consumables; include contingency; compare with the budget.
Question 3: How would you handle this situation: Paint?
Buy two tins for 8 L, subject to coverage and coats.
Question 4: What does this example teach: Timber $85, fasteners $18, delivery $25.?
Subtotal is $128 before contingency.
Question 5: Name one mistake to avoid.
Ignoring pack sizes or minimum order quantities.
Review checklist
- Can you explain the main idea in your own words?
- Can you apply the method to a new example?
- Have you checked the relevant facts, figures and instructions?
- Can you identify a common mistake and avoid it?