Mortar Sand Calculator

Inputs

Unit system Metric Imperial

Switches labels and converts internally.

Area

m²

Masonry/plaster area to receive mortar.

Average mortar thickness

mm

Typical ranges: 10–15 mm for plaster, 8–12 mm for bedding.

Waste allowance

%

Covers spill, rework, and handling losses.

Dry volume factor

Common range: 1.25–1.35 (wet to dry).

Mix ratio (cement : sand)

:

Example: 1 : 4 for masonry mortar.

Sand bulking (moisture)

%

Increases loose volume at ordering time.

Sand density

kg/m³

Typical dry sand: about 1500–1700 kg/m³.

Cement density

kg/m³

Typical cement bulk density: about 1440 kg/m³.

Cement bag size

kg

Used only for estimating number of bags.

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Example data table

Sample inputs and typical outputs for quick reference.

These values assume dry factor 1.33 and sand density 1600 kg/m³.

Formula used

1) Wet mortar volume: V_wet = A × t, where A is area and t is average thickness.

2) Waste allowance: V_waste = V_wet × (1 + w/100).

3) Dry volume estimate: V_dry = V_waste × F, where F is the dry volume factor.

4) Sand share by mix ratio: V_sand = V_dry × (S / (C + S)).

5) Bulking for ordering: V_sand,loose = V_sand × (1 + b/100).

6) Weight: W_sand = V_sand × ρ, with density ρ in kg/m³ (internally).

Professional guide to mortar sand planning

1) Purpose

Reliable sand takeoff keeps masonry and plaster work moving. It reduces emergency purchases, prevents inconsistent batching, and supports clean cost tracking. Use a recorded method so supervisors, storekeepers, and procurement teams work from the same assumptions.

2) Measure the right area

Enter the true surface that receives mortar: bedding, plaster, repairs, or pointing zones. Break complex work into simple rectangles and sum them. If openings exist, subtract them only when the mortar coverage genuinely reduces.

3) Choose a practical thickness

Thickness is the strongest driver of volume. Use an average based on joint depth, plaster specification, and surface tolerance. A quick site check with a ruler across several locations usually produces a better value than drawings alone.

4) Convert wet volume to dry materials

The calculator computes wet mortar volume from area and thickness, then applies waste. It then multiplies by a dry volume factor (often 1.25–1.35) to estimate the loose ingredient volume needed to produce the finished mortar.

5) Apply the mix ratio

Mortar ratios are commonly given as cement:sand by volume. After the dry volume is known, the sand portion is taken as S/(C+S). Keep this aligned with the approved mix design, including any blended binders or additives.

6) Account for moisture bulking

Moist sand can occupy more loose volume than dry sand. If you order by truck volume, apply a bulking percentage to avoid short delivery. The calculator reports both dry sand volume and loose (bulked) volume for purchasing clarity.

For stock control, density turns volumes into weights. If supplier data is unavailable, perform a quick field check: fill a known container with sand, weigh it, and calculate density. Re-check when the sand source changes or after heavy rain, because moisture and grading can shift bulk density.

7) Example with sample data

Example inputs: area 30 m², thickness 12 mm, mix 1:4, waste 10%, dry factor 1.33, bulking 20%, sand density 1600 kg/m³. Estimated dry sand is about 0.421 m³, loose sand about 0.506 m³, and sand weight about 674 kg.

8) Final review

Before ordering, compare the result with crew output and past projects. Increase waste for difficult access, uneven substrates, or frequent re‑mixing. Keep a short record of inputs and actual consumption to calibrate future estimates. This improves accuracy and supports consistent mortar quality across the project lifecycle.

FAQs

1) What does the dry volume factor represent?

It converts wet mortar volume to the loose ingredient volume needed for batching. It covers voids, compaction, and shrinkage between mixed mortar and dry materials. Common planning values are 1.25–1.35.

2) Should I order sand using dry volume or loose volume?

Order using loose (bulked) volume if your supplier sells by truck volume. Track consumption using dry volume and weight for better control. Use a bulking allowance when sand is damp.

3) How do I choose a mortar thickness?

Use an average thickness based on workmanship and substrate tolerance. Verify by measuring a few completed areas or joint depths. For plaster, include variations from leveling and surface irregularities.

4) Which mix ratio is typical for masonry mortar?

Many projects use 1:4 or 1:5 by volume, but specifications vary by exposure, unit type, and strength requirements. Always follow the approved mix design and any relevant standards for your project.

5) Why does moisture increase sand volume?

Thin water films push particles apart, increasing the apparent volume of loose sand. This bulking effect depends on grading and moisture content. If ignored, volumetric batching can become sand‑lean.

6) Can I use this for plaster and pointing work?

Yes. Enter the correct area and thickness for the layer or joints, then set the mix ratio used on site. Adjust waste and bulking to match access, rework, and moisture conditions.

7) Why do my results differ from previous projects?

Differences usually come from thickness, workmanship, sand density, moisture, and waste. Confirm the units and inputs, then calibrate the dry factor and waste percentage using a small trial batch and field measurements.