Per 1m³ of finished concrete, 25kg cement bags, no waste added (add 5–10% for your job).
Mix
Used for
Cement
All-in ballast
1:4
Driveways, heavy use
17 bags (410kg)
1.64 t
1:5
Slabs, paths, shed bases
14 bags (342kg)
1.71 t
1:6
Foundations, footings
12 bags (293kg)
1.76 t
The sum
Dry materials ≈ 2,050kg per m³ of concrete
Cement = 2,050 ÷ (mix parts + 1) e.g. 1:5 → 2,050 ÷ 6 = 342kg = 14 bags
Ballast = 2,050 − cement
Not sure of your volume? The concrete calculator works it out from the length, width and depth, and compares the cost with ready-mix.
Frequently asked questions
Which concrete mix should I use?
1:4 for driveways and anything taking vehicles, 1:5 for general slabs, paths and shed bases, and 1:6 for foundations and footings.
How much water for a cubic metre of concrete?
Roughly half the weight of the cement in water: about 170 litres for a 1:5 m³. Add it gradually; too much water makes weak concrete.
Is it cheaper to mix concrete or buy ready-mix?
For about 1m³ or more, ready-mix is often similar in price and saves a day of mixing. Below that, many suppliers charge extra for a part load, so mixing yourself usually wins.
