Mortar Calculator

Work out how many bags of mortar mix you need to lay a given number of bricks or blocks.

How the Math Works

The Mortar Calculator uses a straightforward formula to determine how many bags of mortar mix you'll need: bags = units divided by units-per-bag, then multiplied by (1 plus the waste factor). First, you divide the total number of bricks or blocks you're laying by how many units each bag of mortar can cover. This gives you the base amount of bags needed. Then, to account for waste, spillage, or uneven mixing, you multiply that base amount by 1 plus your estimated waste percentage (for example, 10% waste becomes 1.10). This ensures you don't run short mid-project.

Practical Applications

To use this calculator practically, start by measuring or counting the total number of bricks or concrete blocks you need to lay. Check your mortar mix packaging to find out how many units (bricks or blocks) one bag can typically cover. Decide on a reasonable waste percentage—usually between 5% and 15% depending on the complexity of your project and your experience level. Plug these three numbers into the formula, and you'll know exactly how many bags to purchase before you start, saving you from multiple trips to the supply store.

Day-to-Day Use

This calculator is a game-changer for DIY enthusiasts and professional builders alike because it eliminates the guesswork from material purchasing. Instead of overbuying mortar and wasting money on unused mix, or worse, running out mid-project and delaying completion, you can confidently plan your material needs in advance. This is especially valuable for weekend warriors tackling home repairs, small contractors managing budgets, or anyone who wants to get their home improvement projects right the first time without costly mistakes or delays.

Worked example

1,000 bricks at 30 per bag + 10% waste → 1,000 ÷ 30 × 1.10 = 37 bags.

FAQ