Example 1
- 1.00 m³ × 350 kg/m³
- +5% waste
- 25 kg/bag, $20
367.50 kg → 15 bags
How much cement for 1 m³ of mortar? 350 kg/m³ × 5% → 367.50 kg (15 bags of 25 kg).
Cement in Mortar Calculator
Enter mortar volume and kilograms of cement per m³. The calculator multiplies them by waste and divides by bag size. 1 m³ at 350 kg/m³ and 5% is 367.50 kg, 15 bags of 25 kg. 0.50 m³ at 430 kg/m³ with no waste is 215 kg, 9 bags. 2 m³ at 250 kg/m³ and 10% is 550 kg, 11 bags of 50 kg.
Results
Enter mortar volume, mix ratio or cement dosage per m³, and waste. The result appears below.
Cement estimate for the mix. Related: mortar requirement, mortar bags.
How the results are calculated
V1 m³
Dosage350
Waste5%
Cement367.50 kg
The cement-in-mortar calculator counts cement alone, not the whole mix. Mass is volume × dosage kg/m³ × (1 + waste/100). Bags are mass divided by bag size, rounded up. The cement:sand ratio only sets dosage.
A full meter at 350 kg/m³ and 5% is 367.50 kg and 15 bags of 25 kg. A richer 0.50 m³ at 430 kg/m³ with no waste is 215 kg and 9 bags. A leaner 2.00 m³ at 250 kg/m³ and 10% is 550 kg and 11 bags of 50 kg.
Enter mortar volume and cement per m³. Ratio, waste, bag size, and price are optional. Without a bag weight, the result stays in kilograms. A comma in 1.00 works the same as a period.
Whole mortar mass lives on mortar requirement, mix bags on mortar bags. 0.3 m³ at 1600 kg/m³ is 21 bags of whole mortar. Enter concrete here only with its m³ and cement recipe.
Bag count rounds up: 14.7 bags is 15. Five percent waste on 350 kg is an extra 17.5 kg. The 1:3 ratio does not multiply volume on its own — pick the kg/m³ dosage from the recipe first.
Enter 1.00 m³ at 350 kg/m³, 5%, and 25 kg: 367.50 kg and 15 bags. Then 0.50 m³ at 430 kg/m³: 215 kg and 9 bags.
How to use this calculator
- Enter mortar volume in m³, for example 1.00 or 0.50.
- Pick a ratio or enter cement per m³ in kg, for example 350.
- Set waste, usually 5–10%, and bag size, for example 25 kg.
- Click Calculate. 1.00 m³, 350 kg/m³, and 5% give 367.50 kg, 15 bags of 25 kg.
- Count full mortar and mix bags in the related calculators. This one counts cement alone.
Formula
cement_kg = volume × dosage_kg/m³ × (1 + waste/100)
bags = ⌈cement_kg ÷ bag_size⌉
1 m³ at 350 kg/m³ and 5%: 367.50 kg, at 25 kg → 15 bags. 0.50 m³ at 430 kg/m³ with no waste is 215 kg and 9 bags.
Dosage and bags
Volume × cement dosage × (1 + waste). 1 m³ at 350 kg/m³ and 5% is 367.50 kg, 15 bags of 25 kg.
- m³
- Mortar volume. 1.00 m³ at 350 kg/m³ and 5% is 367.50 kg of cement.
- kg/m³
- Cement dosage. 350 on 1 m³ plus 5% is 367.50 kg. 430 on 0.50 m³ with no waste is 215 kg.
- kg
- Bag size. 367.50 ÷ 25 = 14.7 → 15. 215 ÷ 25 = 8.6 → 9.
- 1:4
- Cement:sand ratio ≈ 350 kg/m³. 1:3 ≈ 430, 1:6 ≈ 250.
Usage examples
Example 2
- 0.50 m³ × 430 kg/m³
- 0% waste
- 25 kg/bag, $22
215.00 kg → 9 bags
0.50 m³ at 430 kg/m³ (1:3) → 215 kg (9 bags of 25 kg).
Example 3
- 2.00 m³ × 250 kg/m³
- +10% waste
- 50 kg/bag, $35
550.00 kg → 11 bags
2 m³ at 250 kg/m³ (1:6) × 10% → 550 kg (11 bags of 50 kg).
Example 4
- 0.15 m³ × 350 kg/m³
- +5% waste
- 25 kg/bag
55.13 kg → 3 bags
0.15 × 350 × 1.05 = 55.125 → 55.13 kg. 55.13 ÷ 25 → 3 bags.
Example 5
- 0.40 m³ × 430 kg/m³
- +8% waste
- 25 kg/bag
185.76 kg → 8 bags
0.40 × 430 × 1.08 = 185.76. 185.76 ÷ 25 → 8 bags.
Example 6
- 0.80 m³ × 250 kg/m³
- +5% waste
- 25 kg/bag
210.00 kg → 9 bags
0.80 × 250 × 1.05 = 210. 210 ÷ 25 = 8.4 → 9 bags.
Example 7
- 0.05 m³ × 350 kg/m³
- +10% waste
- 25 kg/bag
19.25 kg → 1 bag
0.05 × 350 × 1.10 = 19.25. 19.25 ÷ 25 → 1 bag.
Example 8
- 0.25 m³ × 350 kg/m³
- +8% waste
- 25 kg/bag
94.50 kg → 4 bags
0.25 × 350 × 1.08 = 94.50. 94.50 ÷ 25 → 4 bags.
Related calculators
Frequently asked questions
How do I calculate cement in mortar from volume and dosage?
Multiply mortar volume by kg of cement per m³ and by (1 + waste/100). 1 m³ × 350 × 1.05 → 367.50 kg, or 15 bags of 25 kg.
How many cement bags for 1 m³ at 350 kg/m³, 5% waste, and a 25 kg bag?
15 bags. Mass 367.50 kg divided by 25 kg and rounded up. 0.50 m³ at 430 kg/m³ needs 9 bags.
How is this different from concrete mix, bed-mass mortar, or premixed mortar bags?
Here you get cement only from m³ and dosage (the ratio sets kg/m³). Concrete with aggregate, bed mass from density, and premixed mortar bag counts live on sibling cards.
How is cement mass calculated?
The calculator multiplies mortar volume by cement dosage per m³ and by (1 + waste/100). 1 m³ at 350 kg/m³ and 5% is 367.50 kg. With a 25 kg bag that is 15 bags.
What does the mix ratio do?
The mix ratio sets the cement dosage: 1:3 ≈ 430, 1:4 ≈ 350, 1:5 ≈ 300, 1:6 ≈ 250 kg/m³. A custom dosage replaces the ratio. The result always comes from the kg/m³ dosage, not from the ratio alone.
What waste should I add?
Usually 5–10%. At 1 m³ and 350 kg/m³, 5% waste lifts mass from 350 kg to 367.50 kg and 25 kg bags from 14 to 15.
How is this different from mortar bags?
Here you count cement alone in the mix. The mortar-bags page counts whole mix mass at about 1600 kg/m³. 0.3 m³ at 1600 kg/m³ is 21 bags of whole mortar, not cement.
Which unit should I use for volume?
Cubic meters in metric. 1.00 m³ at 350 kg/m³ and 5% is 367.50 kg. In US units the field shows cubic feet.
Is bag size required?
No. Without a bag weight, the result stays in kilograms. At 25 kg and 367.50 kg the calculator shows 15 bags, because 14.7 rounds up.
Where do I get mortar volume?
From the mortar-requirement page or from the drawing. Enter concrete volume here only when you want cement in that mix.
Does a comma in 1.00 work?
Yes. A comma and a period are the same volume. At 1 m³, 350 kg/m³, and 5% the result stays 367.50 kg.
What is the primary result?
Cement mass, for example 367.50 kg at 1 m³ and 350 kg/m³ with 5%. Bags and cost appear beside it when you enter bag size and price.
Does the result replace a datasheet?
No. The calculator is a purchase estimate. Manufacturer dosage may need an adjustment.
Is this a free cement-in-mortar calculator?
Yes. Enter volume, kg/m³ dosage, and waste and you see kilograms and bags at once. No account required.
Knowledge sources
Cement dosage per m³ comes from the mix ratio. Mass is volume × dosage. Mass and volume units below from NIST.
Page updated October 12, 2026.