Sakrete Concrete Calculator (Metric)
Enter your slab size in metres and depth in centimetres to get the cubic metres of concrete and how many 36 kg or 27 kg bags of Sakrete you need.
What your result means
The 36 kg bag count is your main number, since the bigger bags are cheaper per cubic metre for anything sizable. The 27 kg count is there if you'd rather lift lighter bags. Buy about 10% over either figure for spillage and odd corners, and once you're past a cubic metre, ready-mix delivered is usually cheaper than bags.
How to use this calculator
- Measure length and width in metres, depth in centimetres.
- Read bags needed (both 36 kg and 27 kg sizes shown).
- Buy 10% extra for spillage and odd corners.
- Mix in a wheelbarrow or rented mixer.
- Use 36 kg bags for large jobs — cheaper per cubic metre.
The formula
Volume in cubic metres is length times width times depth (centimetres to metres). A 36 kg bag yields about 0.017 m³ and a 27 kg bag about 0.0127, so divide the volume by the bag yield and round up.
Worked example
A 2 by 1 m slab 10 cm deep is 0.20 m³, which is 12 bags of 36 kg Sakrete (or 16 of the 27 kg). Buy about 10% over for spillage.
Sakrete bag yield
| Bag | Yield | Bags per cubic metre |
|---|---|---|
| 36 kg | 0.017 m³ | 59 |
| 27 kg | 0.0127 m³ | 79 |
| 18 kg | 0.0085 m³ | 118 |
Tips & gotchas
- A 36 kg bag yields about 0.017 m³; a 27 kg bag about 0.0127.
- Past a cubic metre (about 59 bags), ready-mix delivered is usually cheaper.
- Use exactly the water on the bag label. Too wet and the concrete loses strength.
- Pour within about 30 minutes of mixing, before it starts to set.
- Cure it 7 days minimum, 28 for full strength.
Frequently asked questions
How many 36 kg bags of Sakrete in a cubic metre?
About 59 bags. Above a cubic metre, ordering ready-mix usually makes more sense.
How much water for a 36 kg bag of Sakrete?
About 3 litres. Always check the bag.
How long does Sakrete take to cure?
Walkable in 24 to 48 hours, full strength at 28 days.
Can I add water to extend the working time?
No. Extra water weakens the concrete a lot. Mix only what you can place.
What's the difference between concrete mix and cement?
Concrete is cement plus sand and gravel. Cement alone is just the binder.
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