Concrete FAQ
By Vinod Kondeti · Updated
Quick answers for planning a pour. For a calculation, use the concrete calculator.
How many cubic feet are in a cubic yard?
27. A cubic yard is 3 ft × 3 ft × 3 ft.
How many 80 lb bags make a cubic yard?
45, at the 0.60 ft³ per bag yield printed on standard concrete mix.
How many 60 lb bags make a cubic yard?
60, at 0.45 ft³ per bag.
How many 40 lb bags make a cubic yard?
90, at 0.30 ft³ per bag.
How much area does one cubic yard cover?
At 4 in thick, 81 ft². At 6 in thick, 54 ft². Divide 27 by the thickness in feet.
Are 40, 60 and 80 lb bags the same concrete?
For a given product, yes. The yield is proportional to weight (about 0.0075 ft³ per lb for standard mix), so three 40 lb bags make the same volume as two 60 lb bags or one and a half 80 lb bags.
Why does my bag yield differ from the calculator?
Specialty mixes such as fast-setting, crack-resistant or 5000 psi mixes can print a different yield. Divide your cubic feet by the yield on your bag.
How much extra concrete should I buy?
The calculator defaults to 10%. Change it to suit your job: use less for precise formed work and more for uneven ground.
How many cubic meters is a cubic yard?
0.7646 m³. This follows from the exact definition 1 yd = 0.9144 m.
Should I use bags or ready-mix?
It depends on access, labour and local prices. One yard is 45 bags of 80 lb, about 3,600 lb of dry mix, so the bag count tells you how much mixing you are signing up for.