Free calculator
Concrete calculator
Punch in your pour. Get what to order, how many bags it'd take, and whether to call the truck.
Results are estimates. Confirm your dimensions, mix and structural requirements against your plans, local code and supplier before you order.
How is it worked out?
Multiply length, width and thickness in feet, then divide by 27 to get cubic yards. A 24 × 20 ft slab at 4 in is 24 × 20 × 0.333 ÷ 27 = 5.93 yd³. Add your extra, then round up to the next quarter yard. In metric, multiply in metres and you've already got m³.
How much extra should you add?
10% covers most jobs. Go with 5% on tight forms over a flat, compacted base. Go higher when the grade's rough or the depth changes across the pour. Coming up short mid-pour costs a lot more than a little left over.
How many bags make a yard?
It takes 45 of the 80 lb bags, 60 of the 60 lb bags, or 90 of the 40 lb bags to make one cubic yard. Those counts use typical yields of 0.60, 0.45 and 0.30 ft³ per bag. Yield varies by mix, so check the bag.
Bags or a truck?
Up to a yard, bags usually make sense. Over that, get a ready-mix quote. Small loads can carry a short-load fee, so ask your supplier about minimums and delivery before you choose.
You've got the concrete figured out. What about the labour?
See where the hours went before payroll is due.
You will clock out automatically when you leave this site.