The number of bags of cement needed to lay 1000 blocks depends on several factors such as the size of the blocks, the mortar mix ratio, and the thickness of the mortar joints. Typically, it takes about 7 to 10 bags of cement (50 kg each) and 2 to 3 tons of sand to lay 1000 standard concrete blocks with a mortar mix of 1:6 (1 part cement to 6 parts sand).

Concrete blocks are available in standard block sizes of 4″, 5″, 6″ and 8″. The nominal dimensions of a 4″ block are approximately 400mm x 200mm x 100mm, a 5″ block is approximately 400mm x 200mm x 125mm, a 6″ block is approximately 400mm x 200mm x 150mm and an 8 inch block approximately 400mm x 200mm x 200mm.

The actual size of concrete block is kept 10mm less than their nominal size for adding mortar joints, so the actual size of a 4″ block are approximately 390mm x 190mm x 90mm, a 5″ block is approximately 390mm x 190mm x 115mm, a 6″ block is approximately 390mm x 190mm x 140mm and an 8 inch block approximately 390mm x 190mm x 190mm.

The mix ratio for laying concrete blocks typically 1:4, 1:5 or 1:6, which means one part cement mix to four, five or six parts of sand. A 10mm thick mortar joints are good more laying concrete blocks.

**Here’s are step to step calculation of how much sand and cement are needed to lay 1000 concrete blocks:-**

- Estimate volume of 1000 6″ blocks with mortar: Volume = 0.4 × 0.2 × 0.15 × 1000 = 12m3
- Estimate volume of 1000 6″ blocks without mortar: Volume = 0.39 × 0.19 × 0.14 × 1000 = 10.374 m3
- Estimate wet volume of mortar: Wet volume of mortar = 12 m3 – 10.374 m3 = 1.626 m3
- Decide mix ratio: A mortar mix of 1:6 (1 part cement to 6 parts sand) is good for laying blocks. Total proportion 1+6 = 7, parts of cement = 1/7, and parts of sand = 6/7.
- Estimate amount of cement: Amount of cement = 2.16/7 = 0.31 m3, cement in kg = 0.31m3 × 1440 kg/m3 = 445 kg, number of bags of cement = 445/50 = approx 9 x 50kg bags.
- Estimate amount of sand: Amount of sand = (2.16/7) × 6 × 1600 = 3000 kg or approximately 3 tons.
- Therefore, it takes about 9 x 50kg bags of cement and approximately 3,000 kg (3 tons) of sand to lay 1000 standard 6″ concrete blocks with a mortar mix of 1:6 (1 part cement to 6 parts sand) and a thickness of 10 mm to lay mortar.

As per rough estimate, one 50 kg bag of Cement can lay about 100 blocks. This implies that it will take about 10 x 50kg bags of cement to lay 1000 blocks.

**Here’s are general guideline how many bags of cement can lay different number of blocks?**

- It will take about 5 bags of 50kg of cement to lay 500 blocks.
- It will take about 10 bags of 50kg of cement to lay 100 blocks.
- It will take about 15 bags of 50kg of cement to lay 1500 blocks.
- It will take about 20 bags of 50kg of cement to lay 2000 blocks.
- It will take about 25 bags of 50kg of cement to lay 2500 blocks.
- It will take about 30 bags of 50kg of cement to lay 3000 blocks.
- It will take about 35 bags of 50kg of cement to lay 3500 blocks.
- It will take about 40 bags of 50kg of cement to lay 4000 blocks.
- . It will take about 4 bags of 50kg of cement to lay 400 blocks.
- . It will take about 3 bags of 50kg of cement to lay 300 blocks.

**Conclusions:**

A 50kg bag of cement can be used to lay approximately 100 blocks with a mortar mix of 1:6 (1 part cement to 6 parts sand). So you would need approximately 10 bags of 50 kg cement to lay 1,000 blocks.