Mortar calculator
Count the cement, sand and water for a cement–sand mortar by its proportion: for masonry, plaster or screed. Enter the volume of mortar, or the area and the layer thickness.
You need
9 bags of 25 kg
0.50 m³ of mortar · 1 : 3 · 222 kg of cement
- Sand
- 768 kg · 0.51 m³
- Water
- about 177 l
- Dry volume: + 5 % reserve, × 1.3 for shrinkage0.500 × 1.05 × 1.3 = 0.683 m³
- Split 1 : 30.683 ÷ 4 = 0.171 m³; × 3 = 0.512 m³
- Cement, 1,300 kg in 1 m³0.171 × 1,300 = 222 kg → 9 bags of 25 kg
Consumption is the average from the «United Kingdom, Ireland, Australia and New Zealand» preset. Check it against your manufacturer's pack.
The calculator gives an estimate by the usual norms. Consumption depends on the product and the surface: check the manufacturer’s data before you buy.
How it’s calculated
- 1
Mortar volume: as entered, or area × layer thickness.
- 2
Add a reserve of about 5 %, then multiply by 1.3: dry cement and sand shrink when mixed with water.
- 3
Split the dry volume by the proportion: for 1 : 3, one part cement and three parts sand.
- 4
Cement in kg = its volume × bulk density (about 1 300 kg/m³); bags = kg ÷ bag weight.
- 5
Sand in kg = its volume × bulk density (about 1 500 kg/m³); water is about 0.8 of the cement by weight.
Worked example
0.5 m³ of cement–sand mortar in the proportion 1 : 3:
The input
- How much
- By volume
- Mortar, m³
- 0.5
- Cement : sand
- 1 : 3
The result
9 bags of 25 kg
0.50 m³ of mortar · 1 : 3 · 222 kg of cement
- Sand: 768 kg · 0.51 m³
- Water: about 177 l
The calculation
- Dry volume: + 5 % reserve, × 1.3 for shrinkage0.500 × 1.05 × 1.3 = 0.683 m³
- Split 1 : 30.683 ÷ 4 = 0.171 m³; × 3 = 0.512 m³
- Cement, 1,300 kg in 1 m³0.171 × 1,300 = 222 kg → 9 bags of 25 kg
How much cement and sand for 1 m³ of mortar?
For 1 m³ of 1 : 3 mortar with a 5 % reserve you need 1.365 m³ of dry mix: 0.341 m³ of cement (about 444 kg — nine 50 kg bags) and 1.02 m³ of sand (about 1 536 kg).
Which proportion to choose?
1 : 3 is the common mortar for screed and plaster; 1 : 4 and 1 : 5 for brick masonry of ordinary walls; 1 : 2 for strong, dense mortar. The more sand, the less cement per cubic metre.
Questions
Why is the dry volume larger than the mortar?
Water fills the gaps between the grains of sand and cement, so about 1.3 m³ of dry components make 1 m³ of mortar.
How much water to add?
Roughly 0.8 of the cement weight for a workable masonry mortar. Add it gradually: the sand’s moisture changes the amount.
Can I count mortar for a brick wall here?
Yes, or use the brick calculator: it counts the mortar for a wall from its size and the bricks.
The same calculator in the Kvadrino app
Kvadrino for Android works offline: enter the room once and get tiles, paint, flooring and an estimate for the client. The app is in closed testing — write to us and we will add you as a tester.
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