Printable worksheet

← Back to the Concrete Block Calculator

In the print window, choose “Save as PDF” as the printer (or print it on paper). Seed 1 rebuilds this exact sheet.

Concrete Block worksheet

Grades 6–7 · CCSS 7.G.B.6

Solve each problem and show your work. Round answers to 2 decimal places where needed.

1.
Problem 1.
- Units: Metric (meters, mm)
- Wall length: 9 m
- Wall height: 2.6 m
- Area of doors and windows: 1.8 m²
- Block length (nominal): 300 mm
- Block height (nominal): 180 mm
- Extra for breakage and cuts: 4%
- Mortar bags per 100 blocks: 3 bags
Find: Blocks to buy
Answer
2.
Problem 2.
- Units: Metric (meters, mm)
- Wall length: 10 m
- Wall height: 2.8 m
- Area of doors and windows: 1.2 m²
- Block length (nominal): 390 mm
- Block height (nominal): 160 mm
- Extra for breakage and cuts: 6%
- Mortar bags per 100 blocks: 4 bags
Find: Blocks to buy
Answer
3.
Problem 3.
- Units: Metric (meters, mm)
- Wall length: 13 m
- Wall height: 2.2 m
- Area of doors and windows: 1.9 m²
- Block length (nominal): 450 mm
- Block height (nominal): 145 mm
- Extra for breakage and cuts: 5%
- Mortar bags per 100 blocks: 3 bags
Find: Blocks to buy
Answer
4.
Problem 4.
- Units: US (feet, inches)
- Wall length: 30 ft
- Wall height: 8 ft
- Area of doors and windows: 10 ft²
- Block length (nominal): 15 in
- Block height (nominal): 7 in
- Extra for breakage and cuts: 6%
- Mortar bags per 100 blocks: 3 bags
Find: Blocks to buy
Answer
5.
Problem 5.
- Units: Metric (meters, mm)
- Wall length: 8 m
- Wall height: 2.1 m
- Area of doors and windows: 1.4 m²
- Block length (nominal): 500 mm
- Block height (nominal): 190 mm
- Extra for breakage and cuts: 5%
- Mortar bags per 100 blocks: 2 bags
Find: Blocks to buy
Answer
6.
Problem 6.
- Units: Metric (meters, mm)
- Wall length: 7 m
- Wall height: 2.6 m
- Area of doors and windows: 1.4 m²
- Block length (nominal): 420 mm
- Block height (nominal): 190 mm
- Extra for breakage and cuts: 6%
- Mortar bags per 100 blocks: 2 bags
Find: Blocks to buy
Answer
7.
Problem 7.
- Units: Metric (meters, mm)
- Wall length: 9 m
- Wall height: 2.6 m
- Area of doors and windows: 1.5 m²
- Block length (nominal): 250 mm
- Block height (nominal): 160 mm
- Extra for breakage and cuts: 5%
- Mortar bags per 100 blocks: 2 bags
Find: Blocks to buy
Answer
8.
Problem 8.
- Units: Metric (meters, mm)
- Wall length: 9 m
- Wall height: 2.8 m
- Area of doors and windows: 1.2 m²
- Block length (nominal): 390 mm
- Block height (nominal): 130 mm
- Extra for breakage and cuts: 6%
- Mortar bags per 100 blocks: 3 bags
Find: Blocks to buy
Answer
9.
Problem 9.
- Units: US (feet, inches)
- Wall length: 36 ft
- Wall height: 6 ft
- Area of doors and windows: 13 ft²
- Block length (nominal): 20 in
- Block height (nominal): 8 in
- Extra for breakage and cuts: 4%
- Mortar bags per 100 blocks: 3 bags
Find: Blocks to buy
Answer
10.
Problem 10.
- Units: Metric (meters, mm)
- Wall length: 11 m
- Wall height: 1.8 m
- Area of doors and windows: 1.4 m²
- Block length (nominal): 360 mm
- Block height (nominal): 160 mm
- Extra for breakage and cuts: 4%
- Mortar bags per 100 blocks: 3 bags
Find: Blocks to buy
Answer

Answer key: Concrete Block worksheet

1. Blocks to buy: 416 blocks
1. Gross wall area = length × height
  $9 \times 2.6$ $= 23.4 m²$
2. Net wall area = gross area − openings
  $23.4 - 1.8$ $= 21.6 m²$
3. Face area of one block = nominal length × height (mm² ÷ 1,000,000 gives m²)
  $\frac{300 \times 180}{1,000,000}$ $= 0.054 m²$
4. Blocks in the wall = net area ÷ block face area
  $\frac{21.6}{0.054}$ $= 400 blocks$
5. Add 4% for breakage and cuts, then round up to whole blocks
  $400 \times 1 + 0.04$ $= 416$ $= rounded up: 416$
6. Mortar = blocks laid × 3 bags per 100 blocks, rounded up
  $\frac{400 \times 3}{100}$ $= 12$ $= rounded up: 12$
2. Blocks to buy: 456 blocks
1. Gross wall area = length × height
  $10 \times 2.8$ $= 28 m²$
2. Net wall area = gross area − openings
  $28 - 1.2$ $= 26.8 m²$
3. Face area of one block = nominal length × height (mm² ÷ 1,000,000 gives m²)
  $\frac{390 \times 160}{1,000,000}$ $= 0.0624 m²$
4. Blocks in the wall = net area ÷ block face area
  $\frac{26.8}{0.0624}$ $= 429.487179 blocks$
5. Add 6% for breakage and cuts, then round up to whole blocks
  $429.487179 \times 1 + 0.06$ $= 455.2564$ $= rounded up: 456$
6. Mortar = blocks laid × 4 bags per 100 blocks, rounded up
  $\frac{429.487179 \times 4}{100}$ $= 17.1795$ $= rounded up: 18$
3. Blocks to buy: 430 blocks
1. Gross wall area = length × height
  $13 \times 2.2$ $= 28.6 m²$
2. Net wall area = gross area − openings
  $28.6 - 1.9$ $= 26.7 m²$
3. Face area of one block = nominal length × height (mm² ÷ 1,000,000 gives m²)
  $\frac{450 \times 145}{1,000,000}$ $= 0.06525 m²$
4. Blocks in the wall = net area ÷ block face area
  $\frac{26.7}{0.06525}$ $= 409.195402 blocks$
5. Add 5% for breakage and cuts, then round up to whole blocks
  $409.195402 \times 1 + 0.05$ $= 429.6552$ $= rounded up: 430$
6. Mortar = blocks laid × 3 bags per 100 blocks, rounded up
  $\frac{409.195402 \times 3}{100}$ $= 12.2759$ $= rounded up: 13$
4. Blocks to buy: 335 blocks
1. Gross wall area = length × height
  $30 \times 8$ $= 240 ft²$
2. Net wall area = gross area − openings
  $240 - 10$ $= 230 ft²$
3. Face area of one block = nominal length × height (in² ÷ 144 gives ft²)
  $\frac{15 \times 7}{144}$ $= 0.729167 ft²$
4. Blocks in the wall = net area ÷ block face area
  $\frac{230}{0.729167}$ $= 315.428571 blocks$
5. Add 6% for breakage and cuts, then round up to whole blocks
  $315.428571 \times 1 + 0.06$ $= 334.3543$ $= rounded up: 335$
6. Mortar = blocks laid × 3 bags per 100 blocks, rounded up
  $\frac{315.428571 \times 3}{100}$ $= 9.4629$ $= rounded up: 10$
5. Blocks to buy: 171 blocks
1. Gross wall area = length × height
  $8 \times 2.1$ $= 16.8 m²$
2. Net wall area = gross area − openings
  $16.8 - 1.4$ $= 15.4 m²$
3. Face area of one block = nominal length × height (mm² ÷ 1,000,000 gives m²)
  $\frac{500 \times 190}{1,000,000}$ $= 0.095 m²$
4. Blocks in the wall = net area ÷ block face area
  $\frac{15.4}{0.095}$ $= 162.105263 blocks$
5. Add 5% for breakage and cuts, then round up to whole blocks
  $162.105263 \times 1 + 0.05$ $= 170.2105$ $= rounded up: 171$
6. Mortar = blocks laid × 2 bags per 100 blocks, rounded up
  $\frac{162.105263 \times 2}{100}$ $= 3.2421$ $= rounded up: 4$
6. Blocks to buy: 224 blocks
1. Gross wall area = length × height
  $7 \times 2.6$ $= 18.2 m²$
2. Net wall area = gross area − openings
  $18.2 - 1.4$ $= 16.8 m²$
3. Face area of one block = nominal length × height (mm² ÷ 1,000,000 gives m²)
  $\frac{420 \times 190}{1,000,000}$ $= 0.0798 m²$
4. Blocks in the wall = net area ÷ block face area
  $\frac{16.8}{0.0798}$ $= 210.526316 blocks$
5. Add 6% for breakage and cuts, then round up to whole blocks
  $210.526316 \times 1 + 0.06$ $= 223.1579$ $= rounded up: 224$
6. Mortar = blocks laid × 2 bags per 100 blocks, rounded up
  $\frac{210.526316 \times 2}{100}$ $= 4.2105$ $= rounded up: 5$
7. Blocks to buy: 575 blocks
1. Gross wall area = length × height
  $9 \times 2.6$ $= 23.4 m²$
2. Net wall area = gross area − openings
  $23.4 - 1.5$ $= 21.9 m²$
3. Face area of one block = nominal length × height (mm² ÷ 1,000,000 gives m²)
  $\frac{250 \times 160}{1,000,000}$ $= 0.04 m²$
4. Blocks in the wall = net area ÷ block face area
  $\frac{21.9}{0.04}$ $= 547.5 blocks$
5. Add 5% for breakage and cuts, then round up to whole blocks
  $547.5 \times 1 + 0.05$ $= 574.875$ $= rounded up: 575$
6. Mortar = blocks laid × 2 bags per 100 blocks, rounded up
  $\frac{547.5 \times 2}{100}$ $= 10.95$ $= rounded up: 11$
8. Blocks to buy: 502 blocks
1. Gross wall area = length × height
  $9 \times 2.8$ $= 25.2 m²$
2. Net wall area = gross area − openings
  $25.2 - 1.2$ $= 24 m²$
3. Face area of one block = nominal length × height (mm² ÷ 1,000,000 gives m²)
  $\frac{390 \times 130}{1,000,000}$ $= 0.0507 m²$
4. Blocks in the wall = net area ÷ block face area
  $\frac{24}{0.0507}$ $= 473.372781 blocks$
5. Add 6% for breakage and cuts, then round up to whole blocks
  $473.372781 \times 1 + 0.06$ $= 501.7751$ $= rounded up: 502$
6. Mortar = blocks laid × 3 bags per 100 blocks, rounded up
  $\frac{473.372781 \times 3}{100}$ $= 14.2012$ $= rounded up: 15$
9. Blocks to buy: 191 blocks
1. Gross wall area = length × height
  $36 \times 6$ $= 216 ft²$
2. Net wall area = gross area − openings
  $216 - 13$ $= 203 ft²$
3. Face area of one block = nominal length × height (in² ÷ 144 gives ft²)
  $\frac{20 \times 8}{144}$ $= 1.111111 ft²$
4. Blocks in the wall = net area ÷ block face area
  $\frac{203}{1.111111}$ $= 182.7 blocks$
5. Add 4% for breakage and cuts, then round up to whole blocks
  $182.7 \times 1 + 0.04$ $= 190.008$ $= rounded up: 191$
6. Mortar = blocks laid × 3 bags per 100 blocks, rounded up
  $\frac{182.7 \times 3}{100}$ $= 5.481$ $= rounded up: 6$
10. Blocks to buy: 333 blocks
1. Gross wall area = length × height
  $11 \times 1.8$ $= 19.8 m²$
2. Net wall area = gross area − openings
  $19.8 - 1.4$ $= 18.4 m²$
3. Face area of one block = nominal length × height (mm² ÷ 1,000,000 gives m²)
  $\frac{360 \times 160}{1,000,000}$ $= 0.0576 m²$
4. Blocks in the wall = net area ÷ block face area
  $\frac{18.4}{0.0576}$ $= 319.444444 blocks$
5. Add 4% for breakage and cuts, then round up to whole blocks
  $319.444444 \times 1 + 0.04$ $= 332.2222$ $= rounded up: 333$
6. Mortar = blocks laid × 3 bags per 100 blocks, rounded up
  $\frac{319.444444 \times 3}{100}$ $= 9.5833$ $= rounded up: 10$