© Infrastructure Health & Safety Association (IHSA)
39 • Institute for Work & Health (IWH)
Example 3
Calculate the weight of the concrete column in kg.
Step 1: Complete the calculation
Volume of a cylinder
Note: To convert inches to decimal feet,
divide by 12.
6" ÷ 12 = 0.5'
9' 6" = 9.5'
r = d ÷ 2 = 3' ÷ 2 = 1.5'
V = π × r² × H
= 3.14 × 1.5' × 1.5' × 9.5' = 67.1175 ft³
Note: 3.14 was used for π. If you use 3.14159 or the π button on the calculator,
you will get a slightly different answer.
Step 2: Locate the unit weight in Table 1.2.
Concrete, stone, reinforced = 150 lbs/ft³
Step 3: Calculate the weight.
Weight = volume × unit weight
= 67.1175 ft³ × 150 lbs/ft³ = 10 067.625 lbs
Step 4: Convert lbs to kg.
1 kg = 2.2 lbs
Note: To convert pounds to kilograms, divide by 2.2.
To convert kilograms to pounds, multiply by 2.2.
10 067.625 lbs ÷ 2.2 lbs/kg = 4 576.193182 kg
