BYTETOOLS

Mortar Calculator

Calculate bags of mortar mix from a brick or block count or from wall dimensions, plus cement, lime and sand volumes for ASTM type N, S, M and O mixes.

1,000
Units to lay
145.8
Wall area (sq ft)
9.27
Mortar volume (cu ft)
0.263
Mortar volume (m³)
10
Bags of mortar mix
$90.00
Estimated bag cost
1.45
Portland cement (cu ft)
2
Cement bags (94 lb)
1.45
Hydrated lime (cu ft)
2
Lime bags (50 lb)
8.69
Sand (cu ft)
0.32 yd³ / 869 lb
Sand (cu yd / lb)

Two independent routes to the same answer: bags from the published units-per-bag yield, and volume from the geometry — the mortar occupies the joint fraction of the wall face through the unit depth. Mix proportions follow the ASTM C270 proportion specification, where the aggregate stays between 2 1/4 and 3 times the combined cementitious volume. A 94 lb bag of portland cement is one cubic foot and a 50 lb bag of hydrated lime about 1 1/4. Bag yields vary enormously between a masonry-cement-and-sand mix and a pre-blended bag, so check your own bag's label and edit the yields. Estimates only.

What is the Mortar Calculator?

The ByteTools Mortar Calculator answers the two questions that come up on every masonry order: how many bags do I need, and how much sand and cement is that if I mix it myself.

  • Two routes to the answer: bags from published yields, volume from the joint geometry
  • ASTM C270 type M, S, N and O proportions with editable bag yields
  • Portland cement in 94 lb bags, hydrated lime in 50 lb bags and sand by volume and weight
  • Works from a unit count or straight from wall dimensions
  • Editable waste allowance for mortar dropped off the board
  • Runs entirely in your browser — nothing uploaded, no signup

How to use the Mortar Calculator

  1. 1

    Choose imperial or metric, then decide whether to work from a unit count or from wall dimensions.

  2. 2

    Enter the brick or block count, or the wall length and height.

  3. 3

    Set the unit length, height, depth and the mortar joint thickness.

  4. 4

    Pick the mortar type and the bag system, editing the bricks and blocks each bag lays if your label says otherwise.

  5. 5

    Read the mortar volume, bag count, and the cement, lime and sand quantities with their bag counts.

About the Mortar Calculator

The ByteTools Mortar Calculator answers the two questions that come up on every masonry order: how many bags do I need, and how much sand and cement is that if I mix it myself. Work from a brick or block count, or from the wall dimensions, and it returns the mortar volume, the bag count at your bag's published yield, and the cement, lime and sand at your chosen mix.

Mix proportions follow the ASTM C270 proportion specification — type M at 1 cement to 1/4 lime to 3 sand, type S at 1 to 1/2 to 4 1/2, type N at 1 to 1 to 6 and type O at 1 to 2 to 9 — all of which keep the aggregate inside the standard's range of 2 1/4 to 3 times the cementitious volume. Bag yields differ wildly, so they stay editable.

Everything runs locally in your browser and nothing is uploaded. Mortar type is a durability decision, not a preference: type S or M below grade and for retaining work, type N for ordinary above-grade walls, and type O only for interior non-load-bearing work. Check your own bag's label and your local code before ordering.

Frequently asked questions

How many bricks will one bag of mortar lay?

It depends entirely on the bag. A bag of masonry cement mixed with sand on site is usually quoted at around 125 bricks or 28 blocks, while a pre-blended 80 lb bag of mortar mix lays closer to 30 bricks or 12 blocks. Both figures are presets here and both stay editable.

What is the difference between type N and type S mortar?

Type N is the general-purpose above-grade mix, roughly 750 psi, made at 1 part cement to 1 part lime to 6 parts sand. Type S is stronger at about 1,800 psi, mixed 1 to 1/2 to 4 1/2, and is what you want below grade, in retaining walls and anywhere with soil or water pressure.

How much sand do I need per bag of cement?

For a type N mix it is six parts sand to one part cement by volume, so a 1 cubic foot bag of portland cement takes about 6 cubic feet — a little over 600 lb — of sand plus a bag of lime. This calculator converts your total mortar volume straight into those quantities.

How much mortar do I need per square metre of brickwork?

A single-skin wall of 215 by 65 mm bricks with 10 mm joints needs roughly 0.02 cubic metres of mortar per square metre of wall, before waste. Because the answer scales with joint thickness and wall depth, this tool derives it from the dimensions you enter rather than quoting one figure.

How much mortar waste should I allow?

Fifteen per cent is a realistic allowance for what drops off the board, gets left in the mixer and stiffens before it is used. Skilled bricklayers waste less, but mortar is the cheapest part of the job and running out mid-course is the expensive part.

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