Free concrete calculator
Concrete Bag Calculator
Estimate how many 40 lb, 60 lb, or 80 lb bags of concrete you need, including waste, bag cost, and equivalent cubic yards.
- Bag cost
- $403
- Concrete volume
- 36.7 cu ft
- Equivalent cubic yards
- 1.36 cu yd
- Bag yield used
- 0.6 cu ft per 80 lb bag
Concrete Bag Estimating Notes
- Bagged concrete is convenient below about one cubic yard; above that, ready-mix usually wins on labor and price.
- One 80 lb bag yields roughly 0.60 cubic feet, so a full cubic yard takes about 45 bags before waste.
- For pours over 50 bags, price a ready-mix short load before committing to DIY bags.
- A 60 lb bag yields about 0.45 cubic feet and a 40 lb bag about 0.30, so changing bag size moves the count substantially.
- Hand mixing realistically tops out around 20 to 30 bags per person per day. Budget the labour, not just the material.
- Buy one or two bags more than the math says. Running short mid-pour leaves a cold joint you cannot undo.
Concrete Bag Calculator FAQs
How many 80 lb bags make one cubic yard?
An 80 lb bag yields about 0.60 cubic feet. Since one cubic yard is 27 cubic feet, it takes about 45 bags before waste and about 50 bags with a 10% allowance.
Are 60 lb or 80 lb concrete bags better?
80 lb bags reduce the number of bags you need, but 60 lb bags are easier to lift and mix. The best choice is usually the largest bag you can safely handle repeatedly.
How many 60 lb bags make one cubic yard?
A 60 lb bag yields about 0.45 cubic feet, so one cubic yard takes roughly 60 bags, or about 66 once you add a 10% waste allowance.
How many bags of concrete for a 10x10 slab?
A 10 by 10 ft slab at 4 inches thick is about 33 cubic feet, or 1.23 cubic yards. That works out to roughly 60 bags of 80 lb mix with waste included, which is right at the point where ready-mix usually becomes the cheaper option.
When is ready-mix cheaper than bags?
Once you pass about one cubic yard. Bags cost more per yard of finished concrete but let you skip the ready-mix short-load fee, so small jobs favour bags and anything larger favours delivery.
How much water does bagged concrete need?
Follow the bag, usually around 3 quarts per 80 lb bag. Extra water makes the mix easier to work but sharply reduces final strength, which is the most common mistake on DIY pours.