Estimate bags of concrete for slabs, footings, and columns, plus blocks, bricks, mortar, and sand for walls. Adjust units and waste factor for instant, real-time results.
Material Estimator
Choose a project type below. Every field updates your results instantly as you type.
Waste Factor
?10%
0%10%20%
Total Concrete Volume (with waste)
?
0.00 yd³
0.00 ft³
0
80 lb bags
0
60 lb bags
0
40 lb bags
Bag rows are alternatives, not additive. Pick one bag size and buy that many bags. Bag yields used: 80 lb ≈ 0.60 ft³, 60 lb ≈ 0.45 ft³, 40 lb ≈ 0.30 ft³.
Total Concrete Volume (with waste)
?
0.00 yd³
0.00 ft³
0
80 lb bags
0
60 lb bags
0
40 lb bags
Bag rows are alternatives, not additive. Pick one bag size and buy that many bags. Bag yields used: 80 lb ≈ 0.60 ft³, 60 lb ≈ 0.45 ft³, 40 lb ≈ 0.30 ft³.
Standard Blocks Needed (with waste)
0
Coverage area divided by unit footprint, including a 0.375 in mortar joint.
0
80 lb bags of Type N Mortar Mix
0.00
Tons of Masonry Sand (bulk mix alternative)
Mortar bags assume pre-blended Type N Mortar Mix (water only, ≈ 0.66 ft³ yield per 80 lb bag). The masonry sand figure is an alternative for buying sand and masonry cement separately, using a typical 1 part cement to 3 parts sand ratio by volume.
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Key Terms Explained
Portland Cement
The fine gray powder binder, made mainly from limestone and clay, that hardens when mixed with water and binds sand and gravel into solid concrete.
Aggregate Ratio
The proportion of sand (fine aggregate) and gravel or crushed stone (coarse aggregate) combined with cement and water, often expressed as a ratio such as 1:2:3.
Waste Factor
An extra percentage added to a material estimate to cover spillage, over-excavation, uneven sub-grade, and small measurement errors.
Slump
A measure of how wet or workable fresh concrete is, tested by filling a cone-shaped mold and measuring how far the mix settles once the mold is lifted.
Cubic Yard
A unit of volume equal to 27 cubic feet (3 ft x 3 ft x 3 ft). Ready-mix concrete is ordered and priced by the cubic yard.
Type N Mortar
A medium-strength, general-purpose mortar (about 750 psi) used for most above-grade brick and block walls and many veneer applications.
Curing
Keeping freshly placed concrete moist and at a stable temperature for several days so it can gain strength properly as it hardens.
Load-Bearing
Describes a wall, column, or footing that carries and transfers structural weight, such as a roof or floor, down to the foundation, as opposed to a purely decorative or partition structure.
The Complete Guide to Concrete and Masonry Estimating
Buying the right amount of concrete and masonry material is one of the most common headaches in any do-it-yourself or contractor job. Order too little and you face delivery minimums, mid-pour shortages, and visible color or texture seams between batches. Order too much and you are stuck disposing of extra bagged mix or paying for ready-mix you never used. This calculator turns your raw dimensions into the numbers that actually matter at the counter: cubic yards of concrete, bag counts by size, blocks or bricks needed, and the mortar and sand to set them.
How to Use This Tool
Start by choosing your unit system, Imperial or Metric, near the top of the calculator. This switches every input label across all three tabs at once, so pick the system that matches your tape measure or plans before entering numbers. Next, set the waste factor slider. A default of 10 percent works for most flat, well-formed pours, but consider raising it toward 15 to 20 percent for irregular shapes, hand-dug footings, or rough ground that will soak up extra mix.
Then select the tab that matches your project. The Slab / Patio tab handles flat pours like patios, sidewalks, and driveways using length, width, and thickness. The Footing / Column tab covers both rectangular strip or pad footings and round columns or piers, with a quantity field so you can estimate a whole run of identical footings at once. The Brick / Block Wall tab estimates how many standard bricks or blocks a wall needs, along with mortar and sand. Every field recalculates instantly, so you can experiment with different thicknesses, depths, or wall sizes and watch the totals respond in real time.
Reading the Concrete Results
For the Slab and Footing tabs, the dark readout panel shows your total volume in cubic yards (or cubic meters in Metric mode) with the waste factor already applied, alongside the same figure in cubic feet for cross-checking against supplier order forms. Below that, three bag-count boxes show how many 80, 60, or 40 pound pre-mixed bags would cover that volume. These three numbers are alternatives to each other, not totals to add together: pick the bag size you intend to buy and use that row. As a quick reference, one cubic yard works out to roughly 45 bags at 80 lb, 60 bags at 60 lb, or 90 bags at 40 lb.
Reading the Wall Results
The Brick / Block Wall tab works differently because you are counting discrete units rather than pouring a continuous volume. The calculator divides your wall's total area by the footprint of one unit plus its mortar joint (a standard 0.375 in joint on two sides), then applies your waste factor to get a unit count. From that same unit count, it estimates the mortar volume needed to fill all those joints and converts it into 80 lb bags of pre-blended Type N Mortar Mix. As a separate, alternative figure, it also estimates the tons of masonry sand you would need if buying sand and mortar cement separately and mixing on site at a typical 1 part cement to 3 parts sand ratio.
Original Insight: Why Thickness and Depth Punish Small Errors
Length and width errors scale your volume linearly, but thickness and depth are usually the smallest dimension in the calculation, which means they are also the easiest to misjudge as a fraction of an inch here or there. Bumping a 10 ft by 10 ft patio from a 4 in slab to a 5 in slab does not just add a little material, it increases the total volume by a full 25 percent, the equivalent of an extra 14 bags at 80 lb. When you are unsure about thickness, it is almost always better to round up to the next standard thickness and let the waste factor absorb the rest, rather than guess low and discover the shortfall mid-pour.
Frequently Asked Questions
A waste factor covers the material that never ends up as finished structure: spillage during mixing and placement, leakage through form joints, over-excavation, an uneven sub-grade that absorbs extra mix, and small rounding errors in your measurements. On a small project these losses might be a fraction of a bag, but on a heavy pour, a patio, driveway, or a run of footings, that same percentage translates into a large absolute volume.
Ready-mix concrete trucks also have minimum order volumes and steep short-load fees, so coming in even slightly under your true requirement can mean paying for an entire extra truck. A default waste factor of 10 percent is reasonable for a flat, well-formed slab on graded ground, while irregular shapes, hand-excavated footings, or rough sub-grades often justify pushing the slider toward 15 to 20 percent.
A widely used general-purpose concrete mix is roughly 1 part Portland cement, 2 parts sand (fine aggregate), and 3 parts coarse gravel or crushed stone, often written as a 1:2:3 ratio, plus enough water to make the mix workable. A slightly leaner 1:2:4 ratio is also common and produces a mix in a similar strength range to what most residential slabs, footings, and sidewalks require, generally in the 3,000 to 4,000 psi class.
These ratios are useful for understanding how site-mixed concrete is proportioned and why the aggregate makes up the majority of the volume. Pre-mixed bagged concrete, the kind this calculator estimates in 80, 60, and 40 pound bags, already combines cement, sand, and gravel in fixed factory proportions, so you only need to add water.
Every brick or block in a wall is surrounded by mortar joints, and that joint thickness gets added to the unit's actual size to determine how much wall area each unit, plus its share of mortar, actually covers. A standard joint is 3/8 inch (0.375 in).
Increasing the joint to 1/2 inch (0.5 in) makes each unit's effective footprint larger, which means fewer units are needed to cover the same wall area, but each of those units now requires more mortar. For a standard 8 in x 16 in block, moving from a 3/8 in joint to a 1/2 in joint reduces the unit count by roughly 3 to 4 percent, while increasing the mortar volume per unit by a noticeably larger percentage, since mortar volume grows with the joint thickness on two dimensions at once. In practice, even small, consistent changes in joint width can shift your mortar mix and sand totals more than they shift your block or brick count.
One cubic yard equals 27 cubic feet. Based on typical manufacturer yields, an 80 lb bag yields about 0.60 cubic feet of mixed concrete, a 60 lb bag yields about 0.45 cubic feet, and a 40 lb bag yields about 0.30 cubic feet.
Bag Size
Yield per Bag
Bags per Cubic Yard
80 lb
≈ 0.60 ft³
≈ 45 bags
60 lb
≈ 0.45 ft³
≈ 60 bags
40 lb
≈ 0.30 ft³
≈ 90 bags
These figures are the same ones this calculator uses to convert your total volume into bag counts, and they explain why larger bags are almost always more cost effective per cubic foot for bigger pours, even though they are heavier to carry.
Type N is a medium-strength, general-purpose mortar (around 750 psi) suitable for most above-grade interior and exterior walls, including standard brick and block work, tuckpointing, and many veneer applications.
Type S is a higher-strength mortar (around 1,800 psi) used where greater bonding strength and flexibility are required, such as load-bearing walls, exterior walls below grade, and areas exposed to higher wind or seismic loads. Type M is the highest-strength common mortar (around 2,500 psi) and is typically reserved for heavy structural loads, foundations, retaining walls, and other below-grade masonry that needs maximum compressive strength.
For most do-it-yourself walls, garden walls, and standard above-grade block or brick projects, Type N is the typical choice, which is why this calculator uses it as the default for bag and sand estimates.