Example 1
- 0.3 m³, 1600 kg/m³
- bag 25 kg, +5% waste
504 kg → 21 bags
This is a practical purchasing scenario because bag count usually matters more than an intermediate result in kilograms or liters.
Mortar bags needed calculator
Type the volume you need and the bag size. The calculator multiplies m³ by density and waste, then divides by the pack and rounds up. Three tenths of a cubic meter at 1600 kg/m³, 5%, and 25 kg is 504 kg, 21 bags. One m³ at 1800 kg/m³, 10%, and 30 kg is 1980 kg, 66 bags.
Also useful: concrete volume, cement in mortar.
Results
Volume needed, Mix type, Bag size (kg) and Custom density (kg/m³). The result shows up here.
How the results are calculated
Mortar bags needed turns volume into packs. Mass is volume times density times (1 plus waste). Bags are ceil(mass divided by bag size). Water is mass times the L/kg ratio when you type it. Mix type fills density; custom density overrides it.
A small repair of 0.3 m³ at 1600 kg/m³, a 25 kg bag, and 5% is 504 kg and 21 bags. A full meter at 1800 kg/m³, 30 kg, and 10% is 1980 kg and 66 bags. A thin 0.15 m³ at 1500 kg/m³, 20 kg, and 0% is 225 kg and 12 bags. 567 kg from the mortar card at 25 kg is 23 bags.
Type volume needed in m³ and bag size in kg. Mix type, custom density, waste, water, and price are optional. A comma in 0.3 works like 0,3. Take volume from mortar requirement or from concrete.
Cement in a 1.00 m³ mix at 350 kg/m³ lives on cement in mortar: 367.50 kg and 15 bags of 25 kg. A 15 mm bed on 20 m² is 567 kg on mortar requirement, then you come back here for bags.
A fraction of a bag goes up. 20.16 bags is 21, not 20. A dry bag and tap water are two entries: the L/kg ratio does not change bag count, it only shows liters of water.
Type 0.3, 1600, 25 kg, and 5%, click Calculate, and match 504 kg and 21 bags. Then 1, 1800, 30 kg, and 10%: 66 bags.
How to use this calculator
- Type volume needed in m³, for example 0.3 from a small repair or 1 from a full meter.
- Pick a mix type or a custom density in kg/m³ and a bag size, for example 25 kg.
- Add waste, usually 5-10%. The water ratio is optional.
- Click Calculate. 0.3 m³, 1600 kg/m³, 5%, and 25 kg give 504 kg, 21 bags.
- Bed mass belongs on mortar requirement. This calculator stays bags.
21 bags from 0.3 m³ of mortar
Volume times density and waste, then bag size rounded up. 0.3 m³ at 1600 kg/m³, 5%, and 25 kg is 504 kg, 21 bags.
- m³
- Volume of mix you need. 0.3 m³ at 1600 kg/m³ and 5% is 504 kg. 1 m³ at 1800 kg/m³ and 10% is 1980 kg, 66 bags of 30 kg.
- kg/m³
- Density from the mix list or the custom field. Standard 1600 on 0.3 m³ plus 5% is those 21 bags of 25 kg.
Usage examples
Example 2
- 1 m³, 1800 kg/m³
- bag 30 kg, +10% waste
1980 kg → 66 bags
After adding reserve, the result reflects real working conditions better and reduces the risk of interrupting the job.
Example 3
- 0.15 m³, 1500 kg/m³
- bag 20 kg, 0% waste
225 kg → 12 bags
For larger work scopes, converting the result into bags makes logistics, cost, and delivery planning easier.
Related calculators
Frequently asked questions
How many bags at 0.3 m³, 1600 kg/m³, 5%, and 25 kg?
21 bags. Mass 504 kg, 504 / 25 = 20.16, rounded up to 21.
How many bags at 1 m³, 1800 kg/m³, 10%, and 30 kg?
66 bags. Mass is 1980 kg after waste, then 1980 / 30 rounds in whole bags.
How many bags at 0.15 m³, 1500 kg/m³, 0%, and 20 kg?
12 bags. Mass 225 kg, exactly 11.25, rounded up to 12.
How many 25 kg bags from 567 kg of mortar?
23. 567 / 25 = 22.68. The 567 kg mass comes from mortar requirement.
What waste should I add for bags?
Usually 5-10%. The calculator still rounds bags up, so 20.16 becomes 21.
Does water change the bag count?
No. The L/kg ratio shows liters of water. Bags follow dry mass and pack size.
Where do I get 0.3 m³?
From mortar requirement (bed times area) or from concrete volume.
How much cement in 1 m³ at 350 kg/m³ and 5%?
367.50 kg, 15 bags of 25 kg on cement in mortar. Here you count the whole mortar, not cement alone.
Can I buy 20 bags when the result is 20.16?
Round up to 21. The last bag covers cuts and the end-of-day mix.
How is mix type different from custom density?
Type fills kg/m³. Custom density overrides the preset. One source at a time.
Knowledge sources
Volume and waste come from the sizes you type. Below are volume and NIST SI units.
Page updated in 2026.