Mortar Calculator
Brick mortar is 8.1 ft³ per 1,000 modular bricks with ⅜ in joints (net), divided by your bag yield: 1,000 bricks need 8.1 ft³: about 16 bags exact at 0.5 ft³ per bag, or 18 with 10% waste. For concrete block, a rule of thumb: about 16 blocks per 80 lb preblended bag, waste included. See the Brick Calculator.
How it's calculated: Brick: mortar = bricks ÷ 1,000 × 8.1 ft³; bags = mortar ÷ yield per bag, rounded up after the waste allowance. Block: 80 lb preblended bags = blocks ÷ 16, with no allowance added.
Result appears here
Fill in the fields and press Calculate.
Formula, calculation, assumptions and sources
Brick: mortar ft³ = (units ÷ 1,000) × 8.1
Brick: Bags (exact) = mortar ft³ ÷ yield per bag; Bags (recommended) = ⌈ mortar ft³ × (1 + waste) ÷ yield ⌉
Block: 80 lb preblended bags = blocks ÷ 16 (rule of thumb, nominal waste included — no allowance added)
Run the calculation to see each step with your own numbers.
1,000 modular bricks, 0.5 ft³/bag yield, 10% waste.
Mortar = 1.0 × 8.1 = 8.1 ft³ → order 8.91 ft³ (10% waste)
Bags = 8.1 ÷ 0.5 = 16.2 exact → ⌈8.91 ÷ 0.5⌉ = 18 recommended
- Brick: 3/8-in mortar joints with full bedding; the 8.1 ft³ per 1,000 is net and the waste allowance is added on top.
- Block: conventional CMU laid with face-shell bedding, 80 lb bags of preblended mortar. The 16-blocks-per-bag rule already includes nominal waste and varies with the mason, non-modular layouts, returns and corners — it is a rule of thumb, not an exact takeoff.
- Pre-blended bagged mortar (Type N or S). Site-batched mortar from masonry cement + sand uses roughly 1 bag cement + 18–27 shovels of sand per ~12 ft³.
- Brick: yield per bag varies by product and mixing water — 0.5 ft³ is a common figure for a 70–80 lb bag.
- Type N or Type S mortar?
- Type N for most above-grade veneer and non-loadbearing work; Type S for below-grade, retaining and structural masonry. The quantity is the same — the calculator counts quantity, not the mix.
- How many bags of mortar per 1,000 bricks?
- About 16 for the exact volume (16.2 at a 0.5 ft³ per bag yield), and 18–19 once you add a normal 10–15% for waste. For conventional concrete block the rule of thumb is about one 80 lb bag of preblended mortar per 16 blocks — about 6.25 bags per 100, nominal waste included.
- Can I mix mortar from cement and sand instead of bags?
- Yes — roughly one bag of masonry cement to 18–27 shovels of sand yields about 12 ft³. The calculator gives the volume you need to hit; the mix is up to you.
- Why is the recommended bag count higher than the exact count?
- The exact count covers the calculated mortar volume only. The recommended count adds your waste allowance for mortar dropped or left to stiffen, then rounds up to whole bags: 8.1 ft³ at 0.5 ft³ per bag is 16.2 exact, 18 recommended at 10%.
Brick mortar
8.1 ft³ of mortar per 1,000 modular brick with 3/8-in joints — a net quantity based on the theoretical joint dimensions, not including waste. Brick Industry Association Technical Note 10 (2009), Table 4.
Block mortar (rule of thumb)
Rule of thumb for conventional CMU (8 × 16 in face) laid with face-shell mortar bedding: one 80 lb bag of preblended mortar lays about 16 units — about 6.25 bags per 100 blocks. The figure includes nominal amounts for waste, and the number of units can vary with the mason's skill, non-modular layouts, returns and corners. Concrete Masonry & Hardscapes Association TEK 04-02A, 'Estimating Concrete Masonry Materials', Table 2.
About the Mortar Calculator
The Mortar Calculator turns a brick or block count into mortar bags. For modular brick it works from 8.1 ft³ per 1,000 bricks with 3/8 in joints (net, before waste), divides by your bag yield and gives the bag count both exact and waste-adjusted, since mortar is dropped, wasted and thrown out once it stiffens. For conventional concrete block it uses a rule of thumb instead: one 80 lb bag of preblended mortar lays about 16 blocks with face-shell bedding, nominal waste already included. It counts quantity, not the mix design.
What you enter
- Masonry unit
- Number of units
- Mortar yield per bag (ft³) — A 60–80 lb bag of pre-blended mortar mix yields ~0.45–0.55 ft³.
- Waste allowance — Default 10%. Adjust to your own allowance — the exact figure is always shown too.
What you get back
- Mortar volume — shown as the exact figure and, separately, a recommended figure with your waste allowance added.
- Bags of mortar mix — Exact = bags for the exact mortar volume; recommended = whole bags including the waste allowance.
- 80 lb bags of preblended mortar (rule of thumb) — Conventional CMU, face-shell bedding: about 16 blocks per 80 lb bag (CMHA TEK 04-02A, Table 2). Nominal waste is already included, so no allowance is added — round up to whole bags. A rule of thumb, not an exact takeoff.
The formula, a worked example, the assumptions behind it and the sources are shown in full below the calculator.
Related calculators
- Brick Calculator — Number of bricks for a wall of a given area and brick size.
- Concrete Block Calculator — Number of concrete masonry units (blocks) for a wall of a given area.
- Block Wall Calculator — Blocks, mortar and fill for a concrete block wall.
- Concrete Block Fill Calculator — Grout volume needed to fill the cores of a concrete block wall.
Part of the Masonry calculators.