From measured volume to chosen bags

Concrete bag calculator

Estimate bag quantities for rectangular concrete sections using the mixed-concrete yield on your selected product. This is a material estimate, not a structural design tool.

METRIC + US UNITSNO INPUTS SENT

Measure your concrete sections.

YOUR MEASUREMENTS

Measurement system

Rectangular sections

Use actual planned dimensions and a uniform thickness for each non-overlapping section. Metric length and width use metres; thickness uses millimetres. US length and width use feet; thickness uses inches. Up to 30 sections.

Volume allowance (%)The 10% default is illustrative. Choose an allowance for actual placement conditions.

Mixed-concrete yield per bag (L)Enter the stated yield of your exact product and bag size, not its dry weight. The 17 L example must be checked against your chosen bag.

Price per bag (your currency)Optional. Enter your actual bag price; leave blank to omit cost.

Inputs stay in this page. Unit changes convert measurements without converting prices. “Currency units” means the same currency you used for the entered price.

Your concrete estimate

ESTIMATED

Calculate an estimate

Whole packages for the entered measurements

Measured volume—

Added volume allowance—

Volume including allowance—

Entered yield per bag—

Whole-bag yield—

Bag rounding above the estimate—

Material cost—

Quantity arithmetic only. This does not choose structural thickness, strength, reinforcement, foundations, mixing water or curing methods. Follow the product label and qualified project requirements.

The example calculates when JavaScript is enabled.

How to use this calculator

Measure each rectangular section and use the specified thickness for your project. This calculator does not determine a safe thickness.
Read the mixed-concrete yield on your chosen product’s bag or current technical data sheet. Enter it in litres or cubic feet as selected.
Choose your volume allowance and optional bag price, then calculate whole bags.
Switching units converts every dimension and the entered yield. Your price and currency stay the same. Reset example restores the starting values.

Yield matters more than the bag’s name.

Volume is length × width × thickness, after unit conversion. Add the selected percentage, divide by the actual yield per bag, and round up to whole bags. There is no universal conversion from bag weight to concrete volume.

Manufacturer yields are approximate. A label may show separately rounded litre and cubic-foot figures; switching units here converts the value you entered exactly rather than replacing it with another printed approximation.

Try the worked example.

The default exampleA 3 m × 2 m section at 100 mm thick contains 0.6 m³. A 10% allowance gives 0.66 m³, or 660 L. With an entered yield of 17 L per bag, 660 ÷ 17 requires 39 whole bags. They yield about 663 L. At 8 currency units per bag, material cost is 312.

Limits worth checking before you buy.

Which product and bag size should I use?

Choose a suitable product with your supplier or qualified contractor, then enter its stated yield. The example is not a product recommendation. Product suitability, mixing instructions, placement limits and local requirements must be checked independently.

Can I calculate post holes, slopes or structural foundations?

This tool models rectangular volumes of uniform thickness only. It does not subtract embedded posts, model curved or tapered holes, validate ground conditions, or design load-bearing work. Use project-specific geometry and qualified design guidance for those cases.

Sources and assumptions

QUIKRETE Concrete Mix No. 1101 technical data sheet lists different yields by bag size, including approximately 17 L for its 80 lb bag. That is the source of this illustrative yield, not a rule for all concrete. Verify the current sheet and safety instructions for the product you buy.

Read the worked home guide