DIYCalcLab

Topic · Masonry estimating

Brick and block counts, joints and mortar bags

By DIYCalcLab Editorial Team · Updated

This page is the method, not the tool list. Brick and block counts start from the face of one unit plus its mortar joint. Mortar bags on the brick calculator use QUIKRETE’s published maximum of 37 standard bricks per 80 lb bag, scaled by joint volume, then a further 10% that the data sheet does not state. Neither number is a structural design.

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Core calculators

Start with the tool that matches your job. Each page shows the formula, defaults, shopping list and sources.

Units per area, then bags

  • Bricks per unit area = 1 ÷ ((brick length + joint) × (brick height + joint))
  • US modular with a 3/8 in joint is 8 × 2.625 in, about 6.86 bricks per square foot
  • Bricks to order = ceil(area × bricks per area × skins × (1 + waste %))
  • Mortar bags on the brick tool = ceil(reference-brick equivalents × 1.10 ÷ bricks per bag). The 37 figure is a published maximum, not a guaranteed average

Variables

Waste on bricks
The brick calculator defaults to 5% for cuts and breakage. That percent is not added again inside the mortar line
Mortar extra
The calculator adds 10% after it converts joint volume to reference bricks. QUIKRETE says published yields do not include waste
Blocks
The block calculator uses its own module and a separate “up to 13 standard blocks per 80 lb bag” figure. Do not divide block counts by 37
Face modules the calculators already contain
FromTo
US modular + 3/8 in8 × 2.625 in face, about 6.86 / sq ft
UK 215 × 65 mm + 10 mm225 × 75 mm face
80 lb mortar, bricksup to 37 standard bricks (QUIKRETE 1102)
80 lb mortar, blocksup to 13 standard 8 × 8 × 16 in blocks (same sheet)

Worked examples

Each example uses the same inputs as the linked calculator. The link loads those inputs; the page URL without parameters stays the canonical.

16 × 3 ft single-skin wall, US modular, default 3/8 in joint, 5% brick waste

Imperial · length 16 ft · height 3 ft · openings 0 · US modular · joint blank · one skin · waste 5%

  1. Area = 48 sq ft. Face module = 6.86 bricks per sq ft
  2. 48 × 6.86 × 1.05 = 345.6 → 346 bricks
  3. Mortar uses about 329 reference bricks of theoretical joint, not 346
  4. 329 × 1.10 ÷ 37 = 9.79 → 10 bags of 80 lb

Result: 346 bricks to order. Mortar purchase: 10 × 80 lb bags. The 10 bags are not 346 ÷ 37.

Open this example in the calculator →

Order units and mortar as separate lines

  1. Count bricks or blocks from face plus joint, including the breakage percent on that calculator.
  2. Read the mortar bags on the same result. Do not divide the purchased brick count, which includes breakage, by 37 and call that official.
  3. If you switch from brick to block, open the block calculator. The per-bag figure changes from 37 to 13.

Brick waste and mortar waste are different lines

  • Brick waste defaults to 5%. The ordered brick count uses that percent. Mortar is estimated from the theoretical joints, not from the extra bricks you bought for breakage.
  • The mortar line then adds 10%. That 10% is in the calculator. The QUIKRETE sheet’s “up to 37” does not include it.
  • Because 37 is a maximum, a real wall can need more bags than count ÷ 37. Rounding up does not remove that limit.

Limits

  • Wall height, piers, retaining soil and reinforcement are outside this page. The brick calculator only warns on a tall single skin. It does not approve the wall.
  • There is no masonry guide on this site. Do not expect a second long article. The two calculators and this method page are the set.
  • A separate mortar-only URL is not published. Both calculators already return a bag count.

Related calculators

    Quick questions

    Does a double skin simply double the brick count?

    The brick count is about twice for the same face area. Mortar is not exactly twice, because the calculator also adds the joint between the two skins. Use the thickness control on the brick calculator rather than doubling a single-skin mortar bag count in your head.

    Why add waste if the bag already says up to 37 bricks?

    “Up to 37” is a maximum yield on the QUIKRETE sheet, and that sheet’s yields do not include waste. The brick calculator still adds 10% when it turns joint volume into bags. Ten bags in the worked example is that calculation, not a promise that 37 bricks will always come out of a bag.

    Does this page decide how high a wall can be?

    No. It counts units and mortar for the height you type. Tall freestanding walls, retaining walls and reinforced masonry need a design this site does not provide. Landscape retaining blocks are a different calculator.

    Sources

    1. QUIKRETE Mortar Mix data sheet No. 1102 — accessed : “Each 80 lb (36.2 kg) bag of QUIKRETE Mortar Mix will lay up to 37 standard bricks or 13 standard (8 in by 8 in by 16 in) blocks.”
    2. QUIKRETE concrete and mortar calculator — accessed : “All yields are approximate and do not include allowance for uneven subgrade, waste, etc.”

    Prefer manufacturer data sheets and published factors. Coverage, yield and waste vary by product — confirm the label you buy.

    Looking for every masonry tool in one list? See the Masonry calculators category hub · Methodology · Updated