Veystrum › Tools › Concrete calculator
How to Calculate Yards of Concrete
Enter the dimensions to estimate cubic yards, 60 lb and 80 lb bags, a 10% waste allowance and optional material cost.
Turn this into a job estimate
Carry the result into a Veystrum Free workspace. No card for the 7-day trial.
Create my free workspaceConcrete yard formula
Convert every dimension to feet. Multiply length × width × depth to get cubic feet, then divide by 27 because one cubic yard contains 27 cubic feet. Multiply by 1.10 when using a 10% waste allowance.
Worked example
A 12 ft × 10 ft slab that is 4 in (0.333 ft) thick is about 39.96 ft³. Divide by 27 for 1.48 yd³, or about 1.63 yd³ with 10% waste.
Frequently asked questions
How many bags equal one cubic yard?
Using typical yields, allow about 60 × 60 lb bags or 45 × 80 lb bags before waste. Check the bag label because yield varies.
What should I measure for steps?
Break the steps into rectangular sections, calculate each volume and add them. The single form can use the combined average dimensions for a quick estimate.
Can I use this to order ready mix?
Use it to plan, then confirm the quantity, minimum load, access and delivery constraints with the supplier.
Related: gravel calculator · roof pitch calculator · construction guides.