Concrete Bags Calculator

Calculate how many bags of pre-mixed concrete you need. Enter volume to see bag counts for 20kg, 25kg, and 30kg sizes with waste factor included.

Part of the Concrete & Masonry calculators — see all tools in this category.

Volume Input

Volume of concrete needed in cubic meters

%

Typical: 10% for spillage and overfill

Custom Yields (Optional)

Leave blank to use default yields. Only override if your product has different specifications.

Default: 0.009 m³ (9 liters)

Default: 0.012 m³ (12 liters)

Default: 0.014 m³ (14 liters)

Cost Estimate (Optional)

Enter bag prices to compare total costs for each size.

$

Price per 20kg bag

$

Price per 25kg bag

$

Price per 30kg bag

Results

Volume with Waste
0.55

Includes 10% waste factor

20kg Bags
62

61.1 calculated, rounded up

25kg Bags
46

45.8 calculated, rounded up

30kg Bags
40

39.3 calculated, rounded up

About Bag Yields

Default yields: 20kg = 9L (0.009 m³), 25kg = 12L (0.012 m³), 30kg = 14L (0.014 m³). These are typical values for pre-mix concrete. Check your product packaging for exact specifications.

How It Works

This calculator helps you determine how many pre-mixed concrete bags to purchase for your project, showing counts for all three standard bag sizes.

  1. Enter the volume of concrete needed: Input the total volume in cubic meters (m³). If you have dimensions, use our Concrete Slab Calculator to find volume first.
  2. Adjust waste percentage: Default is 10% which accounts for spillage, mixing losses, and slight over-ordering. Increase for complex pours or inexperienced mixing.
  3. View bag counts for all sizes: See how many 20kg, 25kg, and 30kg bags you need. Compare to find the best option based on price and handling preference.
  4. Optional: Add custom yields: If your specific product has different yields than the defaults, enter them in the Advanced section for accurate calculations.
  5. Optional: Enter bag prices: Add price per bag for each size to see total cost estimates and find the most economical option.

Formula: Bags Needed = Volume (m³) × (1 + Waste%) ÷ Yield per Bag (m³)

Frequently Asked Questions

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