Mortar Calculator

One form: the wall, the brick, the mortar

Most mortar calculators start where this one finishes: the only masonry takeoff page in the measured top six wants a brick count you do not have yet. Here the wall goes in once — length, height, openings — and brick, mortar and sand come out together, in US customary units or metric. That switch is on no readable page of the six.

The quantities come from one document, the brick industry’s own estimating note, and its sentence is careful: Table 4 presents the estimated quantities of brick and mortar (not including waste) required for brick masonry according to the size of brick used in the wall. The mortar quantities are based on theoretical dimensions of the mortar in the wall. Not including waste, and theoretical — so the allowance here is your field, opening at 5 percent. At zero this wall orders 1350 brick instead of 1418. None of the calculators we could read cites anything.

Eight bags per 1,000 brick

There is a trade rule for mortar, and the ranking calculators are built on it. It is the sentence just before the one above: Masons frequently use a rule of thumb that eight bags of masonry cement will lay 1000 modular brick. This is a very rough estimate and includes an unspecified amount of waste.

Why this sheet does not use it. A figure its own publisher calls very rough, with an unspecified amount of waste already inside, is not one you can order against. The warning is quoted here; the rule is never computed with.

It reads a published volume instead, by brick size and joint, in two columns: per 100 square feet, or per 1,000 brick when you have a count. Each is rounded on its own, so they disagree — 1,000 modular brick at 3/8 inch is 8.1 cubic feet one way, 8.148 the other, 0.59 percent apart. The takeoff line names the basis it read.

The joint picks a column, it is not added on

A modular brick is listed at its nominal size and the joint is already inside it: four inches of module is the brick plus its joint. So the 3/8 or 1/2 inch choice selects which published quantities to read, and adding the joint on top counts the same mortar twice. The column matters — this wall goes from 11.55 cubic feet at 3/8 inch to 14.49 at 1/2 inch, with the brick count unmoved. Queen, King, Standard and Engineer Standard are the exception the field names: specified dimensions, the unit itself, and the joint still selects a column.

Sand, cubic foot for cubic foot

Sand has a rule of its own: The commonly used “rule of thumb” is appropriate: 1 cubic foot (cubic meter) of loose, damp sand will yield about one cubic foot (cubic meter) of mortar. The sand line therefore equals the mortar line, 11.55 cubic feet here. This sheet stops at volume: the source publishes no density for masonry sand, so no weight and no tonnage is printed here. By the ton, take the volume to C-103.

Hollow brick, face-shell bedded

Structural hollow brick is usually bedded on the face shells, and the quantities may come down by the voids in the unit — typically 25 to 35 percent. The toggle applies your figure to the mortar and nothing else: at 30 percent this wall drops from 11.55 to 8.09 cubic feet and still orders 1418 brick.

Type M, S, N or O

The type changes what goes in the mixer, not how much the wall swallows: the volumes above hold whichever one you specify. The proportions live in the specification this note points to, ASTM C270, and are not reprinted here: choosing between the types is a job for your plans and your local code.

Net      An =  L x H - sum( w x h x count )   (sq ft)
Brick    B  =  An / 100 x per100(size)
Order    Bo =  ceil( B x (1 + waste / 100) )
Mortar   Mv =  An / 100 x per100cf(size, joint)
or       Mv =  N / 1000 x per1000cf(size, joint)
Bedded   Mb =  Mv x (1 - voids / 100) x (1 + waste / 100)
Sand     Sv =  Mb                        cu ft for cu ft
Bags     Bg =  ceil( Mb / yield )        from your label

Worked example: a 40 foot facade with four openings

Forty by nine feet, three 3 by 5 foot windows and a 3 by 7 foot door, modular brick, 3/8 inch joint, 5 percent.

1. Gross 360 sq ft, less 66 of openings: 294 sq ft net.
2. Brick: 1985 in the wall, 2084 to order.
3. Mortar: 16.17 cu ft in the wall, 16.98 to buy.
4. Sand: 16.98 cu ft, loose and damp.

Frequently asked

How do you calculate how much mortar you need?

From wall area, or from a brick count. This 200 square foot wall of modular brick takes 11 cubic feet at a 3/8 inch joint, 11.55 with your 5 percent on it; at 1/2 inch, 14.49.

How many square feet will a 50 lb bag of mortar cover?

We do not guess at it. Nothing we opened publishes how much mortar a 50, 60 or 80 lb bag of preblended mix yields, so the bag count stays blank until you type the cubic feet per bag from your own bag's label. Type it in and the sheet counts bags.

How much mortar calculator?

This one, free. Brick size, joint, wall or count in; brick, mortar, sand and bags out, with the arithmetic shown.

Should I use type S or type N mortar?

Type N is the general-purpose mortar for above-grade veneer; type S is specified where the wall takes more lateral load or sits below grade. The proportions are the standard's, and are not printed here.

Limits of this sheet

A-202 turns a brick elevation into a count, a mortar volume and the sand to match, from one published set of quantities — read it at BIA Technical Note 10. Single wythe, running or stack bond: header patterns, collar joints, chimneys, repointing and stonework take more mortar. Laying concrete block? The block sheet counts the units and their mortar — A-201. Confirm with your plans, your supplier and your local code.

Sheet A-202 prepared by TakeoffMetric Editorial; no author, credential or field measurement is claimed.