How to use it
- Enter the slab length in feet in the Length field.
- Enter the slab width in feet in the Width field.
- Enter the slab thickness in inches in the Thickness field.
- Click Calculate to see cubic yards, cubic feet, and the number of 80-lb bags needed.
Concrete work stalls when you're short on mix. This calculator tells you exactly how much Sakrete concrete to order before you start. Enter the length, width, and thickness of your slab, and it instantly returns cubic feet, cubic yards, and the number of 80-lb bags you'll need — using the standard yield of 0.6 cubic feet per bag.
The result matters because concrete is sold by the cubic yard and in 80-lb bags. One bag gives only 0.6 cubic feet, so a small patio can easily need 50+ bags. Your cubic yards figure is what you'd compare against a ready-mix order; your bag count is what you'd bring home from the store. The cubic feet number helps you double-check both.
Read the bag count as a minimum. Round up to the next full bag, then add a small waste allowance so one bad pour doesn't stop the job.
Pro tips
- Add 5–10% extra for spillage, uneven subgrade, or slight depth variations.
- Always round bag count up to the next whole bag — never order a fraction of a bag.
- Break irregular areas into rectangles, calculate each one, then add the totals together.
- Double-check the thickness is in inches, not feet, before you calculate.
Real-life examples
- Pouring a 10x10 patio slab at 4 inches thick.
- Ordering bags for a concrete walkway or sidewalk.
- Estimating material for a shed foundation or small footer.
Case study
Mario needed a 10×10×4-in slab. He entered the numbers and saw about 1.23 cubic yards and 56 bags. He ordered 58 bags, added a little waste, and finished without a second trip to the store.