Cement Calculator
Work out Portland cement bags, sand, gravel, and water for any concrete or mortar mix ratio.
Concrete mode only. Enter the finished pour dimensions, or use Known volume instead.
Concrete mode only. Use the finished slab or pour thickness.
Concrete mode only. A positive value overrides Length × Width × Thickness.
The default 1:2:3 concrete mode uses current QUIKRETE recipe/yield evidence. Custom modes require your own verified ratio or yield.
94 lb is the traditional U.S. sack weight. A 94 lb bag occupies about 1 ft³ in loose bulk form; that is a batching convention, not an ASTM C150 yield rule.
Custom mode only. Relative loose-volume parts.
Custom mode only. Relative loose-volume parts.
Custom concrete only. Relative loose-volume parts.
Custom mortar only. Enter 0 if your user-supplied recipe intentionally contains no hydrated lime.
Custom concrete only. Enter a supplier, specification, or trial-batch cement requirement expressed as 94 lb bag-equivalents per finished cubic yard. The calculator will not invent a yield for a custom ratio.
Mortar mode scales dry ingredients from the Portland cement you plan to batch. It does not predict finished mortar volume or field strength.
How to Use
- Choose the recipe mode - use the manufacturer-backed 1:2:3 concrete mode, a custom concrete ratio with your verified yield, or a Type S / Type N / custom Portland-cement mortar recipe.
- For concrete, enter finished volume - use length × width × thickness or enter a known cubic-yard volume. Custom concrete also requires the verified cement bag-equivalent yield for that mix.
- For mortar, enter cement bags - the calculator scales hydrated lime and masonry sand from the Portland cement in your batch. It does not infer finished mortar yield.
- Choose the cement bag size - 94 lb is the U.S. reference sack; 47 lb is one-half of that cement mass and loose-volume basis.
- Use allowance only for concrete purchasing - 5%, 10%, or 15% is an explicit planning allowance. Mortar recipe mode uses the batch quantities you enter without adding an automatic waste factor.
QUIKRETE says five to six 94 lb bags of Portland cement are typically used with appropriate sand and gravel to produce 1 cubic yard of concrete, and its published concrete recipe is 1 part cement : 2 parts sand : 3 parts gravel by volume. CalcShed uses 6 bags per yd³ as the conservative default planning basis, then applies your selected allowance. At the default 10% allowance, 1 yd³ plans for 7 whole 94 lb bags, about 13.2 ft³ of sand, and 19.8 ft³ of gravel.
Cement Is Not Concrete - What This Calculator Figures
Cement is the binding powder; concrete is the finished mixture of cement, sand, gravel, and water. This calculator is for site batching with straight Portland cement. The default concrete mode is anchored to QUIKRETE's published 1:2:3 recipe and its typical five-to-six 94 lb bags per cubic yard yield. If you are buying premixed bags instead - bags that already contain cement and aggregates - use the Concrete Bag Calculator for 40, 60, and 80 lb premix bag counts.
A 94 lb Portland cement sack is not a 94 lb bag of ready-to-use concrete. NCDOT's concrete mix-design manual notes that a 94 lb cement bag occupies about 1 ft³ in loose bulk form but only about 0.48 ft³ as absolute solid volume. That loose-volume convention is useful for field batching, while finished concrete yield depends on the complete mix rather than a universal dry-volume multiplier.
What a 1:2:3 Mix Ratio Means
Concrete and Mortar Mix Ratios Compared
The calculator now separates sourced recipe proportions from finished-yield assumptions. Nominal ratios alone do not establish a concrete PSI or a mortar field strength:
| Mode | Dry-volume recipe | Yield / scaling basis | Scope |
|---|---|---|---|
| 1 : 2 : 3 concrete | 1 cement : 2 sand : 3 gravel | QUIKRETE: typically 5-6 × 94 lb cement bags per yd³; calculator plans with 6 | General site-batching estimate; not a specified strength mix |
| Custom concrete | User-entered cement : sand : gravel | User must enter a verified 94 lb bag-equivalent cement yield per finished yd³ | Use only with supplier, specification, or trial-batch yield evidence |
| Type S mortar | 1 Portland : 1/2 hydrated lime : 3.5-4.5 masonry sand | Scales from the Portland cement bags in the batch | ASTM C270 proportion recipe; no finished-yield or field-strength claim |
| Type N mortar | 1 Portland : 1 hydrated lime : 4.75-5.75 masonry sand | Scales from the Portland cement bags in the batch | ASTM C270 proportion recipe; no finished-yield or field-strength claim |
| Custom mortar | User-entered Portland : lime : sand | Scales from the Portland cement bags in the batch | User-supplied recipe only; no ASTM type or strength claim |
ASTM C270 covers mortar through proportion and property specifications and cautions against treating field mortar strength as equivalent to laboratory property-specification strength. For engineered concrete, use the project mixture design rather than inferring PSI from a nominal bucket ratio.
How the Calculator Works It Out
The calculation depends on the selected mode:
Default 1:2:3 cement basis = Finished yd³ × 6 × (1 + planning allowance) = 94 lb bag-equivalents
Custom concrete cement basis = Finished yd³ × your verified 94 lb bag-equivalents/yd³ × (1 + allowance)
Sand / gravel = Loose cement volume ÷ cement parts × sand or gravel parts
Whole cement bags = Calculated cement weight ÷ selected bag weight, rounded up
Type S / N mortar = Entered Portland cement loose volume × the published lime and masonry-sand proportion range
Planning water reference = Concrete cement weight × 0.50 ÷ 8.34 lb/gal; actual water is adjusted to the mix design, aggregate moisture, and required consistency
Why the Calculator Does Not Use One Universal Dry-Volume Factor
The old model multiplied every finished concrete volume by 1.54 and every mortar volume by 1.33. That is too rigid for a U.S. calculator because yield changes with aggregate grading, moisture, particle packing, air, proportions, and the actual materials. QUIKRETE instead publishes a typical concrete yield of five to six 94 lb Portland cement bags per cubic yard with appropriate sand and gravel. The default calculator uses the conservative six-bag end of that range. For any other concrete ratio, CalcShed requires you to provide the verified cement yield rather than quietly inventing another universal factor.
The displayed concrete-water quantity is only a w/c 0.50 planning reference. QUIKRETE instructs users to use the minimum water needed for the required consistency and warns that excess water can reduce strength and durability. Aggregate moisture and a project mix design can materially change the amount of water you actually add.
Sources & Standards
- QUIKRETE publishes the 1:2:3 concrete recipe, the typical five-to-six 94 lb bags per cubic yard yield, Type S and Type N Portland-cement/lime mortar proportions, and the instruction to use the minimum water needed for the desired consistency.QUIKRETE Portland Cement - Technical Data Sheet
- NCDOT's ACI-based mix-design manual distinguishes loose bulk volume from absolute volume and notes that a 94 lb cement bag occupies approximately 1 ft³ in bulk form but about 0.48 ft³ of absolute volume.NCDOT Concrete Mix Design Manual
- ASTM C270 covers masonry mortar by proportion or property specification and explicitly warns that field-tested mortar strength is not equivalent to laboratory property-specification strength.ASTM C270 - Standard Specification for Mortar for Unit Masonry
- ACI 211.1 proportioning considers absolute volume, aggregate gradation, workability, strength, durability, w/cm, and trial-batch adjustment. A nominal volume ratio alone is not a reliable PSI specification.ACI PRC-211.1-22 - Selecting Proportions for Normal-Density and High-Density Concrete
Worked Example: 12 × 10 ft Patio, 4 Inches Thick
Finished volume: 12 × 10 × (4 ÷ 12) = 40 ft³, or 1.48 yd³. On the default 1:2:3 mode, CalcShed uses 6 × 94 lb cement-bag equivalents per finished yd³. With the default 10% planning allowance: 1.48 × 6 × 1.10 = 9.78 bag-equivalents, so the purchase quantity rounds up to 10 bags of 94 lb Portland cement.
Using the same 1:2:3 loose-volume recipe, 9.78 ft³ of cement corresponds to about 19.6 ft³ of sand (0.72 yd³) and 29.3 ft³ of gravel (1.09 yd³). The w/c 0.50 planning reference is about 55 gallons, but actual mixing water should be adjusted for aggregate moisture, required workability, and the project mix. The Sand Calculator can convert the sand volume for supplier ordering.
After You Know Your Bag Count
Cement is one of four ingredients. Here is the usual sequence from here:
Batching your own to save money? Benchmark against what a finished concrete slab actually costs in 2026 - materials and labor, by size and region.
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Frequently Asked Questions
How many bags of cement do I need for 1 yard of concrete?
QUIKRETE says five to six 94 lb Portland cement bags are typically used with appropriate sand and gravel to produce 1 cubic yard of concrete. CalcShed uses 6 bags/yd³ as the conservative default before your planning allowance. With the default 10% allowance, that becomes 6.6 bag-equivalents and rounds up to 7 whole 94 lb bags to buy.
What is the difference between cement and concrete?
Cement is the binder. Concrete is cement plus fine aggregate, coarse aggregate, and water. A 94 lb Portland cement bag is therefore not interchangeable with a 60 or 80 lb premixed concrete bag. QUIKRETE's Portland-cement data says five to six 94 lb cement bags, with appropriate sand and gravel, typically produce one cubic yard of concrete.
Should I buy Portland cement or premixed concrete bags?
That depends on local material prices, delivery charges, labor, storage, access, and the quantity you need. Premix is simpler because the aggregates are already proportioned; straight Portland cement lets you batch separate sand and gravel. For larger work, compare both with a local ready-mix quote rather than relying on a universal cost cutoff.
What mix ratio should I use for a driveway?
Do not choose a driveway concrete strength from a nominal bucket ratio alone. Required strength, air entrainment, aggregate, w/cm, freeze-thaw exposure, placement, and curing belong to the project mixture specification. The calculator's 1:2:3 mode is a material-planning recipe, not a promise of a particular PSI.
How much water do I add per bag of cement?
The calculator shows w/c 0.50 only as a planning reference, which is about 5.6 gallons per 94 lb of cement. QUIKRETE says to use the minimum water necessary for the desired consistency and warns that too much water can weaken the material. Aggregate moisture and the specified mix can change the actual water added.
How does the mortar mode work?
Type S mode scales 1 part Portland cement, 1/2 part hydrated lime, and 3.5-4.5 parts masonry sand. Type N scales 1 part Portland cement, 1 part hydrated lime, and 4.75-5.75 parts masonry sand. Those are QUIKRETE Portland-cement mortar proportions consistent with ASTM C270. Mortar mode scales the dry batch from your cement bags; it does not claim a finished mortar volume or field compressive strength.