🧱 Cement Bag Calculator
Calculate the exact number of cement bags required for concrete, plaster, and brick mortar. Includes mix ratios, sand and aggregate requirements, and cost estimation. Perfect for contractors, builders, and DIY projects.
Cement per m³ (M15)
6.3 bags
≈ 315 kg
Plaster Coverage
110 sq ft
per bag (12mm, 1:6)
Brickwork Mortar
4.5 cu ft
per bag (1:4)
Avg Cement Price
₹380/bag
50 kg bag
Project Details
Cement Required
16
Bags800 kg
Total Cost
₹ 6,080
@ ₹380/bag
Material Breakdown
Sand Required
12.5 cu ft
Aggregate Required
25.0 cu ft
Quick Reference Guide
1 bag covers 80 sq ft
1 bag covers 110 sq ft
1 bag covers 4.5 cu ft brickwork
1 bag covers 4.5 cu ft concrete
How to Calculate Cement Bags?
Standard formula: Volume of cement = (Ratio of cement / Total ratio) × Dry volume. Dry volume is 1.54 times wet volume for concrete, and 1.33 times for plaster/mortar. One cement bag = 50 kg = 1.25 cubic feet approximately.
Concrete
Cement = (Vol × 1.54 × cement ratio) / total ratio
Example: 100 cu ft M15 = 16 bags
Plaster
Cement = (Area × Thick × 1.33 × cement ratio) / total ratio
Example: 500 sq ft, 12mm, 1:6 = 4.5 bags
Mortar
Cement = (Vol × 1.33 × cement ratio) / total ratio
Example: 100 cu ft, 1:4 = 16 bags
❓ Frequently Asked Questions
How many cement bags for 100 sq ft slab?
For a 5" thick M15 slab (100 sq ft): 22-25 bags of cement. For 4" thick: 18-20 bags. Use our calculator for precise estimation based on your thickness.
What is 1.54 in concrete calculation?
1.54 is the dry volume factor. When dry materials (cement, sand, aggregate) are mixed with water, they occupy less volume due to chemical reaction and air voids. Wet concrete volume is approximately 54% less than dry volume. So dry volume = wet volume × 1.54.
How many square feet does one cement bag cover for plaster?
For 12mm thick plaster:
• 1:4 mix: 1 bag covers 80 sq ft
• 1:6 mix: 1 bag covers 110 sq ft
For 15mm thickness: coverage reduces by about 20%.
What is the volume of one cement bag?
One standard cement bag (50 kg) has a volume of 1.25 cubic feet or 0.035 cubic meters. Density of cement is approximately 1440 kg/m³.
What is the difference between M15, M20, M25 concrete?
'M' stands for Mix, number indicates characteristic compressive strength in N/mm² after 28 days.
• M10 (1:3:6): 10 N/mm² - For PCC, footings
• M15 (1:2:4): 15 N/mm² - For general RCC work
• M20 (1:1.5:3): 20 N/mm² - For structural RCC, slabs, beams