Mortar Calculator
Calculate mortar — bags from volume and yield per bag. Enter mortar dimensions to get instant results. Enter dimensions, select units and add waste to get instant, supplier-ready numbers.
Enter dimensions above to calculate
- Enter values to see step-by-step substitution.
Engineering Assumptions:
- Use mixed yield from the product data sheet; bags of equal mass can have different yields.
- This estimates a known volume. It does not select a mortar type or grout specification.
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TOP VIEW — Volume × Mixed yield per bag
SECTION — Material allowance 6%
What Is This Calculator?
The Mortar Calculator — Mixes mortar, grout and cement for US masonry — volume, bags and sand ratios.
What Does It Calculate?
- Mortar volume in cubic feet
- Cement bags (94-lb) and sand
- Water and cost with waste
How to Use the Calculator
- Measure Mortar 20 ft x 10 ft x 4 in — use feet for length/width and inches for thickness where typical.
- Enter values and select units. The calculator converts to feet before calculating (inches /12, yards x3).
- Adjust waste % and optional price, then click Calculate. Results show with waste included.
- Use Reset to clear and try another size.
Formula & Engineering Methodology
Bags = ceil(required mixed volume × allowance factor / mixed yield per bag).
- L — Length for Mortar in feet
- W — Width for Mortar in feet
- D — Depth for Mortar in feet
All units convert to exact standard engineering dimensions (NIST SP 811) before calculation to ensure consistency between US Customary and Metric measurements.
Worked Example
Example: Mortar 20 ft x 10 ft x 4 in
| STEP | VALUE |
|---|---|
| Convert depth | 4 in /12 = 0.333 ft |
| Cubic feet | 20 x 10 x 0.333 = 66.67 ft3 |
| Cubic yards | 66.67 /27 = 2.47 yd3 |
| With 10% waste | 2.72 yd3 |
Construction Information
Material: Portland cement 94-lb bag, 1 ft3. Mortar Type S 1:3, Type M 1:2, Type N 1:4. Grout 1:2 cement:sand.
- Measure longest x widest; split L-shapes into two rectangles and add.
- Compact subgrade — soft spots add thickness.
- For structural sizing (beams, headers, rebar) verify with a professional per local code.
Material Information
Portland cement 94-lb bag, 1 ft3. Mortar Type S 1:3, Type M 1:2, Type N 1:4. Grout 1:2 cement:sand.
Waste & Overages
Add 10% for spillage and retemper — mortar stiffens in 90 min.
Practical Tips
- Mix small batches — do not add water after stiffening
- Keep sand damp for consistent mix
Common Mistakes
- Wrong ratio — weak mortar cracks
- Too much water — weak and shrinks
Assumptions & Engineering References
- Use mixed yield from the product data sheet; bags of equal mass can have different yields.
- This estimates a known volume. It does not select a mortar type or grout specification.
This calculator provides an estimate based on your inputs. Actual requirements vary by site, material and installation. For code-regulated or load-bearing work, consult a qualified professional.
Calculations run 100% in your browser — zero tracking of your dimensions or input data.
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Frequently asked questions
What does the Mortar Calculator calculate?
The Mortar Calculator estimates mortar quantity for US jobs — Mortar volume in cubic feet, Cement bags (94-lb) and sand, Water and cost with waste. Enter dimensions, choose units, add waste and price to get instant results.
How do I measure for mortar?
Measure mortar 20 ft x 10 ft x 4 in on site. Use the unit selectors — the tool converts inches→feet (÷12) and yards→feet (×3) before math. For non-rectangular, split into rectangles and add.
How much waste should I add?
Add 10% for spillage and retemper — mortar stiffens in 90 min.
How accurate is this mortar estimate?
Math is exact for your inputs. Actual needs vary by site, material and installation. Add 5–10% waste for rectangular, 10–15% for irregular.
About Calculator Street
Built by Vipul Otari for US homeowners & contractors. Calculator inputs are processed in your browser. Estimates depend on your measurements, product specifications and the assumptions shown on this page. Confirm order quantities with your supplier and structural requirements with your project designer. Page updated: 2026-09-11.