How Much Mortar Do I Need?

How Many Bags of Mortar for 1,000 Bricks?

With a confirmed coverage of 37 standard bricks per bag and a chosen 10% mortar waste allowance, 1,000 bricks need 30 whole bags: 1,000 ÷ 37 × 1.10 = 29.729…. At a hypothetical $9 per bag, the mortar costs $270 before tax and delivery.

The coverage example is specific to QUIKRETE Mortar Mix No. 1102 in an 80 lb bag. Its data sheet also lists an upper coverage of 13 standard 8 × 8 × 16 in blocks per bag. Both figures need checking against the actual units and work; neither establishes a universal bag yield.

Calculate mortar bags from your takeoff and product coverage

Mortar, Concrete and Core-Fill Grout Are Different Estimates

Mortar is used for masonry joints. Concrete for a footing and grout for hollow block cells are separate materials and takeoffs. Do not use a concrete bag’s volume yield as a mortar bag yield, or add block core filling to a joint-mortar estimate. Choose the specified mortar product with the supplier or mason.

Calculate Mortar Bags from Units to Be Laid

First establish how many bricks or blocks will actually be laid. Exclude unused spare units purchased for breakage. If you already have a reviewed takeoff, enter that count directly instead of estimating it again from wall area.

Obtain the number of units one bag lays for the exact product, bag size and application. Base bag equivalents = units to lay ÷ units laid per bag. Multiply by (1 + mortar waste percentage ÷ 100), then round up once for the purchase quantity.

Use the unrounded bag equivalents when adding waste. For 100 blocks at 13 blocks per bag, 100 ÷ 13 × 1.10 = 8.461…, so buy 9 bags. Rounding the base figure first can change an order near a boundary.

If your supplier gives only a mixed volume per bag, you also need a reliable mortar-volume takeoff. Bag volume alone does not tell you how many bricks or blocks it lays. Do not invent a units-per-bag figure from package weight.

Match Coverage to the Joint and Bedding Method

Joint width and depth, unit dimensions, wall thickness, bedding method and workmanship affect consumption. A rate for standard block may not apply to a different width, fully bedded construction or a different mortar product.

Changing joint width in wall mode changes the estimated unit count, but it does not automatically change the coverage per bag. Obtain an applicable rate for the new joint geometry. Do not treat a simple proportional adjustment as a manufacturer yield.

Measure Actual Unit Faces and Deduct Openings

For one rectangular masonry layer, gross area = length × height. Subtract the combined door and window area. Wall mode includes a separate Opening area input; do not reduce the wall dimensions and then subtract the same openings again.

Use actual unit length and height, then add the joint width once to each dimension for the repeating face module. Do not add joints to already nominal dimensions. Divide net wall area by that module area in consistent units and round up to whole units.

For a 20 ft × 8 ft wall with a 20 sq ft opening, net area is 140 sq ft. An actual 15 5/8 in × 7 5/8 in block face with 3/8 in joints forms a 16 in × 8 in module. The count is 140 × 144 ÷ 128 = 157.5, rounded to 158 units. Confirm corners, bond, cuts and additional masonry layers against the plans.

The same measurements are 6.096 m × 2.4384 m, an opening of 1.8580608 m², a 396.875 × 193.675 mm face and a 9.525 mm joint. Switching measurement units keeps this project and the entered coverage and price. A regional 390 × 190 mm block is a different product, not a conversion of this block.

Using Other Products and Metric Bag Sizes

A 60 lb, 25 kg or 30 kg package needs its own confirmed coverage. Select My product / supplier coverage and enter units laid per bag. Do not scale the named 80 lb examples by weight unless your product guidance explicitly supports doing so.

For a hypothetical supplier-confirmed rate of 12 blocks per bag, 180 blocks with 10% mortar waste require 180 ÷ 12 × 1.10 = 16.5, rounded up to 17 bags. At a quoted $11 each, the bag cost is $187. The 12-block rate is an arithmetic example, not a rating for a particular kg bag.

Common Mortar Estimating Mistakes

Check these before ordering:

• Adding mortar waste to a unit purchase count that already includes unused spares.
• Rounding base bags up before applying waste.
• Using nominal block dimensions and adding the joint twice.
• Changing wall units but accidentally replacing the project or supplier coverage.
• Treating brick, block, veneer, parging and repointing as interchangeable applications.
• Using a named coverage example without checking the product and wall details.

Before Buying and Mixing

Confirm the product, package, takeoff and coverage basis with your supplier or mason. The calculator’s editable 10% allowance is a planning choice, not a manufacturer requirement. If your coverage already allows for job losses, avoid adding them twice. Follow the product’s storage, mixing, water and working-time instructions.

Source and Coverage Basis

The manufacturer sheet below supports the two named coverage examples. Check current documentation for the exact product supplied locally. The calculator does not recommend a mortar type or infer a mixed volume.

QUIKRETE Mortar Mix No. 1102 — manufacturer product data

Mortar Estimating Limits

Use this guide for material planning. Unit count, joint geometry, bond, wall construction and site losses can change the order. Follow the project specification and manufacturer instructions for mortar suitability and construction; the calculator does not perform a structural design.