Concrete Pro Calc
1:2:4 Mix Ratio | 50kg Bags
*Enter thickness in total inches (e.g. 4 for a 4" slab)
💡 Why trust these results?
1. The "Shrinkage" Rule: Dry cement and sand have air gaps. When water is added, the volume shrinks by about 35%. To get 1m³ of finished concrete, we start with 1.54m³ of dry material.
2. The 1:2:4 Ratio (M15): We use the standard mix for small slabs and footings:
• 1 Part Cement
• 2 Parts Sand
• 4 Parts Gravel
3. Spillage & Waste: We automatically add 5% extra. On small sites, sand gets lost in the grass and cement dust blows away; this buffer covers those losses.
4. Bag Standard: Calculated for a 50kg bag (0.035m³ or 1.25ft³).
DISCLAIMER: This calculator is provided for estimation purposes only. Actual material requirements may vary based on local aggregate quality, moisture content (bulking of sand), and site conditions. The 1:2:4 ratio is a general-purpose mix (approx. M15/2000 psi). Users should verify quantities with their local supplier or a qualified engineer before placing orders. We are not liable for any material shortages, surpluses, or structural issues resulting from the use of this tool.