Mortar Calculator
Calculate mortar volume, cement and sand for brickwork or blockwork.
Please note: Material estimates for planning only. Always confirm quantities against your drawings, local building codes and supplier specifications before ordering. Structural work requires a qualified engineer.
What the Mortar Calculator does
Mortar quantity comes from the volume of joints to fill, split by the cement-to-sand ratio. Dry ingredients bulk up by roughly 30% relative to the mixed mortar, so the dry volume exceeds the wet volume you actually place.
Formula
Order volume = Required volume × (1 + Waste %)Dry volume = Order volume × 1.3Cement volume = Dry volume ÷ (1 + Sand parts)Cement bags = Cement volume × 1,440 ÷ Bag size
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Mortar volume required | m³ | Yes | Accepts more than 0. |
| Mortar mix (cement : sand) | one of 4 options | Yes | — |
| Cement bag size | kg | Yes | Accepts 1 or more. |
| Waste allowance | % | Yes | — |
| Price per cement bag | selected currency | Optional | Accepts 0 or more. |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose Mortar mix (cement : sand) and Currency.
- Enter Mortar volume required, Cement bag size and Waste allowance.
- Optionally add Price per cement bag.
- Select Calculate.
Worked example
1 m³ of 1:5 mortar with 15% waste and 50 kg bags.
- Volume
- 1
- Mix
- 1:5
- Bag
- 50
- Waste
- 15
Order 1.15 m³, dry 1.495 m³ → cement 0.249 m³ = 359 kg = 8 bags, sand 1.246 m³.
Frequently asked questions
Which mortar mix should I use?
1:5 or 1:6 for general brickwork, 1:3 or 1:4 where strength matters. Mortar should always be weaker than the brick so cracks form in the joint, not the unit.