Enter your wall or paving area dimensions and mortar joint size to instantly calculate mortar volume, bag counts, and total material cost estimate.
Free to use
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No sign-up required
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Works for brick, block, stone & pavers
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Imperial & metric supported
✓ Bag count (60 lb & 80 lb)✓ Cost estimator included✓ Works on any device✓ Last verified May 2026
Written by Rachel Sousa — formulas cross-checked against ASTM C270 mortar standards, May 2026.
Enter Your Mortar Project Dimensions
Horizontal span of the wall or paving area.Please enter a valid length greater than 0.
Vertical height of wall. For flat paving, enter 1 foot or leave at 1.Please enter a valid height greater than 0.
Standard brick: ⅜ in. CMU block: ⅜ in. Stone / rubble: ½–¾ in.Please enter a valid joint size greater than 0.
Percentage of the wall face occupied by mortar joints. Standard brick ~17%; CMU ~6%; stone ~25–35%.
Add 10–15% for standard jobs. Add 15–20% for stone or irregular coursing.
$
Leave blank to skip cost estimate. US average: $8–$14 per 60 lb bag of type S mortar mix.
Results appear instantly. No sign-up required.
Your Mortar Estimate
Mortar Volume (with waste)
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Cubic Feet (ft³)
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Cubic Yards (yd³)
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Cubic Meters (m³)
Bags Required (includes waste)
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40 lb bags
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60 lb bags
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80 lb bags
—Wall Area (sq ft)
—Joint Size
—Joint Coverage
—Waste Factor
Estimated Material Cost
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Mortar bag material cost only. Add labor ($2–$6/sq ft), mixing equipment, and any bonding admixtures for a full project budget. Use our Full Project Estimator for a complete breakdown.
Step 1: Convert all dimensions to feet (joint size to feet)
Step 2: Wall Area (ft²) = Length (ft) × Height (ft)
Step 3: Joint Volume (ft³) = Wall Area × (Joint Coverage % ÷ 100) × Joint Size (ft)
Step 4: Final Volume (ft³) = Joint Volume × (1 + Waste% ÷ 100)
Step 5: Bags = CEIL(Final ft³ ÷ bag yield) — never round down
Measure your wall or paving area.
Use a tape measure to get the length and height of your wall (or length and width for a flat paving area). If the wall has openings like windows or doors, deduct their area from the total — mortar is only needed where units are being laid. Record dimensions in whatever unit is convenient; the calculator handles conversion.
Select your joint size and use the quick-select buttons.
Standard brick and CMU block jobs use a ⅜-inch joint. Natural stone or rubble work often runs ½ to ¾ inch. Use the preset buttons to fill the joint size instantly without typing decimals. If your spec calls for something different, type it directly into the field.
Set the joint coverage percentage for your unit type.
This is the fraction of the wall face covered by mortar joints, not the brick or block itself. Standard running bond brickwork is about 17%. CMU block walls with only horizontal bed joints and vertical head joints at the ends run around 6%. Rubble or flagstone work with wide irregular joints can reach 35%. The default (17%) is right for most brick jobs.
Review your bag count and order materials.
The calculator outputs bag counts for 40 lb, 60 lb, and 80 lb bags. Most masonry supply yards sell mortar mix by the bag or pallet. If you enter a price per 60 lb bag, the cost estimate gives you your material-only budget. Always confirm quantities with your mason or supplier — mortar volumes for custom stone patterns can vary significantly.
⚠ Pro Tip: Mortar has a working life of roughly 1.5–2.5 hours from the time water is added. Don't mix more than you can place in that window. It's far better to mix two smaller batches than to re-temper (add water to) mortar that has stiffened — re-tempered mortar loses bond strength and violates ASTM C270 requirements.
Mortar Volume Formula
Mortar quantity is calculated by determining the total volume of joints in the wall — not the gross volume of the wall itself. The joint coverage percentage accounts for the fraction of wall area occupied by mortar rather than masonry units.
Step
Formula
Example (20 × 8 ft wall, ⅜ in joint, 17% coverage)
1. Wall area
Length × Height
20 ft × 8 ft = 160 ft²
2. Joint size to feet
inches ÷ 12
0.375 ÷ 12 = 0.03125 ft
3. Net joint volume
Area × Coverage × Joint (ft)
160 × 0.17 × 0.03125 = 0.85 ft³
4. Add waste factor (10%)
Volume × 1.10
0.85 × 1.10 = 0.935 ft³
5. Bags (60 lb, 0.45 ft³ yield)
CEIL(ft³ ÷ 0.45)
CEIL(0.935 ÷ 0.45) = 3 bags
Common Project Reference Table
Net mortar volumes and 60 lb bag counts — no waste factor applied. Add 10–15% for ordering.
Wall Area
Unit Type
Joint Size
Net ft³
60 lb Bags
100 ft²
Standard Brick
⅜ in
0.53
2 bags
200 ft²
Standard Brick
⅜ in
1.06
3 bags
500 ft²
Standard Brick
⅜ in
2.66
6 bags
100 ft²
CMU Block
⅜ in
0.19
1 bag
200 ft²
CMU Block
⅜ in
0.38
1 bag
500 ft²
CMU Block
⅜ in
0.94
3 bags
100 ft²
Rubble Stone
½ in
1.25
3 bags
200 ft²
Rubble Stone
½ in
2.50
6 bags
CMU coverage ≈ 6%. Brick coverage ≈ 17%. Rubble stone coverage ≈ 30%. Bag yield: 60 lb = 0.45 ft³. No waste factor applied — add 10–15% for real ordering.
Which Mortar Type Do I Need?
Choosing the wrong mortar type is one of the most common — and most costly — mistakes in masonry work. ASTM C270 defines the standard types. Selecting too-strong a mortar for soft brick is just as problematic as using too-weak a mortar for a structural wall.
ASTM C270 mortar type selection guide by application.
Mortar Type
Compressive Strength
Best For
Notes
Type M
2,500 PSI
Below grade, retaining walls, driveways
High strength, low flexibility — not for historic brick
Best all-around choice for most residential masonry
Type N
750 PSI
Interior walls, above-grade non-load-bearing
High flexibility, ideal for soft brick and stone veneer
Type O
350 PSI
Interior non-load-bearing, historic restoration
Very flexible — do not use in exterior or wet conditions
Type K
75 PSI
Historic preservation only
Softer than old lime mortars; specialty use
For most homeowner projects — brick garden walls, patio pointing, block foundations — Type S is the correct default. It offers a balance of strength and flexibility that handles moisture, freeze-thaw cycles, and minor structural movement without cracking the units themselves.
Common Mortar Estimation Mistakes
⚠️
Using total wall volume instead of joint volume.
Mortar only fills the joints between units — not the whole wall. Calculating mortar as if it fills the entire wall volume produces estimates 4–10× too high. The correct approach is: wall area × joint coverage fraction × joint thickness. This calculator does that automatically.
🧱
Using the same joint coverage for every unit type.
A standard brick wall has far more joint area than a CMU block wall of the same size. Running bond brick is roughly 17% joints; CMU is about 6% because the units are much larger. Using the brick percentage on a block wall will have you buying three times too many bags.
💧
Re-tempering stiffened mortar.
Adding water to mortar that has started to set and remixing it is called re-tempering. It is prohibited by ASTM C270 because it disrupts the hydration process and dramatically reduces bond strength. If your mortar has stiffened beyond workability, discard it and mix a fresh batch.
🌡️
Ignoring temperature limits at mixing and placement.
Mortar should not be mixed or applied when air temperatures are below 40°F (4°C) or above 95°F (35°C) without cold- or hot-weather protection measures. Freezing before cure causes permanent bond failure. Hot, dry conditions accelerate set time dramatically and can cause premature drying before the mortar bonds to the units.
📐
Not accounting for door and window openings.
Estimating mortar for the gross wall area including windows, doors, and other voids means over-ordering — sometimes by 15–30% on a heavily fenestrated facade. Subtract the area of all openings from your wall area before calculating. The savings on materials and disposal of unused bags adds up.
Frequently Asked Questions
For 100 square feet of standard running bond brickwork with ⅜-inch joints and approximately 17% joint coverage, you need roughly 0.53 cubic feet of mortar before waste. At 0.45 ft³ per 60 lb bag, that's 2 bags before waste — order 3 bags to include a 10% waste factor. The exact number depends on your joint size and brick pattern: Flemish bond or stack bond has different joint ratios than standard running bond.
Mortar is a paste of cement, sand, and water (sometimes with lime) used to bond masonry units — bricks, blocks, or stone — together. It has a stiff, workable consistency and must form a strong bond with the unit faces. Grout is a flowable, cement-based material used to fill voids — typically the hollow cores of CMU block walls or the gaps between wall tiles. Grout does not bond masonry units together; it fills hollow spaces to add mass, strength, or embed rebar. Never substitute one for the other.
Type S mortar is the standard choice for most exterior masonry work — brick walls, block retaining walls, paving, and outdoor chimneys. It has a compressive strength of 1,800 PSI and good freeze-thaw resistance. Type M (2,500 PSI) is appropriate for below-grade work like foundation walls and retaining walls in contact with the ground. Avoid Type N outdoors in freeze-thaw climates; it is too flexible and can allow water infiltration. For any application, confirm the mortar type with the masonry unit manufacturer — using a mortar stronger than the brick can cause spalling of the brick faces.
Mortar reaches initial set in 1–2 hours and is firm enough to tool joints within 30–60 minutes of placement in standard conditions (70°F, moderate humidity). It achieves sufficient strength to resist light loading after 24 hours. Full design strength is reached at 28 days, the same curing timeline as concrete. Avoid loading a freshly mortared wall for at least 24 hours and keep new work from freezing during the first 24 hours. In hot, dry weather, lightly dampen freshly laid masonry to slow moisture loss and ensure proper hydration.
The industry-standard joint size for most brick masonry in the USA is ⅜ inch (about 9.5 mm). This applies to both the bed joint (horizontal) and the head joint (vertical between brick ends). Thinner joints — ¼ inch — are sometimes used for glass block or thinner format bricks. Thicker joints — ½ to ¾ inch — are common in stone masonry or when laying rough, irregular units. The joint size has a significant effect on mortar quantities: doubling the joint from ⅜ to ¾ inch roughly doubles your mortar volume.
Yes, for small repairs — tuck-pointing a chimney, repointing a short section of wall, or patching a few joints — pre-mixed mortar in tubes or buckets is a practical solution. However, pre-mixed products are substantially more expensive per cubic foot than dry bag mixes and are not appropriate for new construction or large-area pointing. For any job over about 20 linear feet of joints, dry bag mix is more economical and produces more consistent results. Check that the pre-mixed product matches the mortar type required by the original work.
For a 60 lb bag of pre-blended dry mortar mix, add approximately 4–5 quarts (roughly 4.5–5 pints) of clean, potable water. Add water gradually — start with 4 quarts, mix thoroughly, then add small amounts until the mortar reaches a smooth, paste-like consistency that holds its shape when squeezed without cracking or crumbling. The correct consistency is often described as "peanut butter." Too much water reduces strength dramatically; too little makes the mix unworkable and leads to poor bond. Always follow the manufacturer's specific water ratio printed on the bag.
CMU block walls require significantly less mortar than brick walls of the same face area because the blocks are much larger and the joint-to-unit ratio is lower. For standard 8×8×16-inch CMU block with ⅜-inch joints, the mortar joints cover roughly 6% of the wall face. A 200 square foot CMU wall needs approximately 0.38 cubic feet of mortar net — about 1 bag of 60 lb mortar mix before waste. Compare that to a brick wall of the same area, which needs around 1.06 cubic feet. Always set the joint coverage field in this calculator to 6% for CMU block work.
It depends on the brick's initial rate of absorption (IRA). Highly absorptive bricks — those that soak up water quickly when dry — should be dampened before laying so they don't pull moisture out of the mortar too fast and cause premature drying. The IRA test: set a brick face-up and pour a small amount of water on it. If it absorbs in under 90 seconds, dampen the brick. If absorption is slow (over 90 seconds), dry laying is fine. Dense, low-absorption bricks like hard-fired engineering bricks or dense concrete bricks generally don't need wetting. Never soak bricks until saturated; they should be surface-damp, not dripping wet.
Tuck-pointing (also called re-pointing) is the process of removing deteriorated mortar from existing joints to a depth of ¾ to 1 inch and filling them with fresh mortar. Because you are filling only the depth of the raked joint — not the full joint depth — mortar quantities are a fraction of what a new wall requires. For estimating a re-pointing job, use this calculator with a joint coverage and joint size appropriate to the existing wall, then reduce the calculated volume by 50–70% since you are only filling the outer portion of each joint. Alternatively, assume roughly 0.25–0.35 ft³ of mortar per 100 square feet of brickwork for a typical re-pointing job.
The people behind this calculator
Rachel Sousa · Written & maintained by
B.S. Civil Engineering, Purdue University. 10+ years turning construction and engineering standards into clear, usable calculator documentation; former documentation lead at a national ready-mix supplier.
