The #1 mistake in bricklaying isn’t the brick—it’s the mortar. Whether you are using pre-mix bags or a custom sand and cement mix, running out halfway through a project is a nightmare. But ordering too much masonry mortar is heavy, messy, and expensive.
Our Mortar Calculator helps you estimate exactly how many 80lb mortar bags or tons of bulk sand you need. It accounts for brick type, joint thickness, and wastage, ensuring your mortar mix ratio is perfect for the job.
How to Use This Calculator
Calculating mortar doesn’t have to be guesswork. Follow this simple workflow to get an accurate mortar estimate:
1
Enter Brick Count
Input the total number of bricks or blocks. (If you don’t have this number, use our Brick Calculator first).
2
Select Mortar Type
Choose Type N for general exterior walls or Type S for structural/high-load walls. The calculator adjusts the price based on type.
3
Choose Bag Size
Select the bag size you plan to buy (e.g., 80lb, 60lb, or 25kg). This ensures the “Total Bags Needed” result matches your local store’s inventory.
4
Get Estimate
Review the total weight and cost. We recommend adding 10-15% extra for waste (spilled mortar or bad mixes).
Pre-Mix Bags: How Many Bricks per Bag?
For small to medium jobs, pre-mix mortar (just add water) is the way to go. Here is the realistic coverage you can expect per bag, assuming a standard 3/8″ joint.
Bag Size
Standard Bricks
CMU Blocks (8″)
80 lb (36 kg)
35 – 40 bricks
10 – 12 blocks
60 lb (27 kg)
25 – 30 bricks
8 – 10 blocks
40 lb (18 kg)
15 – 20 bricks
5 – 6 blocks
25 kg (UK/Metric)
20 – 25 bricks
6 – 8 blocks
💧 The “Peanut Butter” Consistency
Don’t drown your mix. For an 80lb bag, you need about 5 to 6 quarts of water. Add 3/4 of the water first, mix it, then add the rest slowly. You want it to stick to the trowel when you turn it sideways—like peanut butter. If it slides off, it’s too wet.
The Math: Cost Comparison
Is it worth the hassle to mix your own? Let’s look at the numbers for two different projects.
Small Job (500 Bricks)DIY Garden Wall
Stick with bags. It’s cleaner and consistent.
Bricks:500
Coverage:~38 bricks/bag
Qty Needed:14 Bags (80lb)
Estimated Cost ($7.50/bag)$105.00
Big Job (10,000 Bricks)House Extension
Go bulk. Bags will cost you a fortune here.
Pre-Mix Price:$2,100 (270 bags)
Site-Mix Sand:10 Tons (~$500)
Site-Mix Cement:80 Bags (~$800)
Estimated Cost (Site Mix)$1,300.00
You Save: ~$800
Site Mix: The “Sand & Cement” Method
For jobs over 1,000 bricks, mixing your own sand and cement is 50% cheaper. But you need to get the ratio right. A weak mix will crumble; a strong mix will crack.
Type
Strength
Mix Ratio (Cement : Lime : Sand)
Where to use it
Type N
Medium
1 : 1 : 6
Standard. Exterior walls, chimneys, BBQ pits. It has “flex” to handle heat and cold without cracking.
Type S
High
1 : ½ : 4.5
Structural. Foundations, retaining walls, driveways. Anything that needs to hold weight or fight soil pressure.
Type M
Very High
1 : ¼ : 3
Heavy Duty. Stone foundations or underground work. Honestly? Overkill for most residential brick jobs.
The “Rule of 1000” Formula1 Ton Sand + 8 Bags Cement = 1,000 Bricks
Common Questions (FAQ)
How many bags of mortar do I need for 1000 bricks?
You will need about 26 to 28 bags of 80lb pre-mix mortar. If you are mixing it yourself with bulk sand, plan on ordering 1 ton of masonry sand and 8 bags of Portland cement.
Can I use “Play Sand” for mortar?
Absolutely not. Play sand is round and smooth. Mortar needs Masonry Sand, which has angular edges that lock together for strength.
Can I add water if mortar gets stiff?
Yes, within the first 90 minutes. This is called “re-tempering.” Add a splash and mix it up. But if the bucket has been sitting for 2 hours and starts to get hard, the chemical cure has started. Adding water now will kill the strength (“killing the mix”). Throw it out.
How long does mortar take to cure?
Mortar is usually “rain safe” in about 24 hours. However, it takes 28 days to fully cure and reach its maximum rated strength (PSI). Do not paint or seal new masonry for at least 30 days to allow moisture to escape.
