Concrete Bag Calculator
Concrete is sold by the bag, but projects are measured in cubic meters. This calculator converts your required volume into the number of bags needed, rounded up for waste.
What Is Concrete Bag?
A concrete bag calculator converts a required concrete volume into the number of bags needed by dividing volume by bag yield. Bag yield is the volume of concrete one bag produces when mixed. Rounding up ensures you have enough for the entire pour.
Example
Formula: Volume / Bag yield = 6 m³ / 0.035 m³/bag = 171.43 bags ≈ 172 bags (rounded up)
Enter volume and bag yield in any unit, then choose result type (rounded or exact).
Tip: Choose result type (rounded or exact) on the right before calculating.
Rounded up is best for purchasing extra bags.
Step-by-step calculation
- Enter total concrete volume and bag yield with units.
- Select result type (rounded or exact).
- Calculate to see bags needed and steps for that mode.
How this is calculated
Required bags = concrete volume divided by yield per bag. A standard 40 kg bag yields about 0.018 m³ of mixed concrete; 25 kg and 20 kg bags yield proportionally less. We add 5–10% for waste and uneven subgrades.
Sources: ACI 211.1 (Selecting Proportions for Normal Concrete); IS 456:2000.
FAQ
- How do I calculate concrete bags by hand?
- Divide total volume by bag yield. Example: 3 m³ / 0.035 m³/bag = 85.7, round up to 86 bags.
- What is the formula for concrete bags?
- Bags = Volume / Bag yield. A 50 kg bag yields about 0.035 m³.
- 40 kg vs 50 kg concrete bags
- 40 kg bags yield less volume per bag, so you need more bags for the same volume.
- What units should I use?
- Use m³ or L for volume and m³/bag or L/bag for bag yield.
- Can I use this for a small patio?
- Yes. Enter your patio volume and bag yield to get the bag count.