Concrete Bag Calculator (40, 60, 80 lb)
Measure the pour; get the 80, 60 or 40 lb bags to buy.
Sources checked 8 November 2026
Concrete bag calculator
How many bags of concrete do I need
Work out the volume in cubic feet, add the extra, and divide by the yield of one bag: an 80 lb bag of Quikrete or Sakrete concrete mix makes about 0.6 cubic feet, a 60 lb bag 0.45 and a 40 lb bag 0.3. Round up to whole bags. A 10 × 10 ft slab, 4 in thick is 33.33 cubic feet; with 10% extra it takes 62 bags of 80 lb, 82 of 60 lb or 123 of 40 lb.
The calculator takes a slab, a footing, a wall, round columns or steps in feet, inches and fractions, and draws the pour to scale.
Read the tape into feet
10′ 0″ = 10 ft. 10′ 0″ = 10 ft. 4″ = 4 ÷ 12 = 0.333 ft.
Multiply for cubic feet
10.00 × 10.00 × 0.333 = 33.33 cu ft
Divide by 27 for cubic yards
33.33 ÷ 27 = 1.23 cu yd
Add the extra
1.23 × 1.10 = 1.36 cu yd. That is the number to order.
Bags: divide by the yield, round up
36.67 cu ft ÷ 0.60 = 61.1, so 62 bags of 80 lb.
Cubic yards = length × width × thickness ÷ 27 × (1 + extra)
10.00 × 10.00 × 0.333 = 33.33 cu ft; ÷ 27 = 1.23 cu yd; × 1.10 = 1.36 cu yd
All sizes in feet. Extra is 10% unless you change it.
Bag yields: 40, 60 and 80 lb bags in a yard
A cubic yard is 27 cubic feet, so it takes 45 bags of 80 lb, 60 of 60 lb or 90 of 40 lb, before any extra. Over about a yard, ready-mix from a truck is usually less work than mixing bags; the concrete calculator gives the yards to order.
| Bag | Yield per bag | Bags for 1 cu yd | Bags on a pallet |
|---|---|---|---|
| 80 lb | 0.60 cu ft | 45 | 42 |
| 60 lb | 0.45 cu ft | 60 | 56 |
| 40 lb | 0.30 cu ft | 90 | 80 |
Yield: Quikrete and Sakrete data sheets. Pallets: Quikrete. Bags for a yard: 27 ÷ yield, before any extra.
How much one yard of bags covers
A cubic yard covers 81 square feet at 4 inches thick and 54 square feet at 6 inches.
| Thickness | Sq ft per cu yd |
|---|---|
| 3.5 in | 92.6 |
| 4 in | 81 |
| 5 in | 64.8 |
| 6 in | 54 |
| 8 in | 40.5 |
Worked out: 27 cu ft ÷ (thickness in inches ÷ 12). No extra added.
| Job | Thickness | Source |
|---|---|---|
| Sidewalk | at least 4 in | Quikrete project sheet |
| Patio | 4 in | Quikrete project sheet |
| Driveway, cars | 4 in | Quikrete project sheet |
| Driveway, trucks or heavy vehicles | 5 to 6 in | Quikrete project sheet |
| Shed base | 4 to 6 in, by load | Quikrete project sheet |
| Garage floor | 4 in typical; 5 to 6 in for heavy vehicles | Quikrete project sheet |
| House floor slab, code | not less than 3 1/2 in | 2025 California Residential Code |
What is in a bag of concrete mix
Bagged concrete mix is a blend of portland cement, sand and gravel or stone; you add only water. Cement is one material in concrete, not the same thing: a bag of cement alone makes no concrete. Quikrete rates its Concrete Mix at 4,000 psi at 28 days, and 2,500 psi at 7 days.
To calculate the amount of concrete, work out the volume of the slab, footing or post holes in cubic feet, then divide by the bag yield: 0.6 cubic feet for an 80 lb bag, 0.45 cubic feet for a 60 lb bag and 0.3 cubic feet for a 40 lb bag. The number of bags you need is that result, rounded up.
How much extra to buy
Forms bow, the ground is never flat, and some mix stays in the barrow. The calculator adds 10%; the National Ready Mixed Concrete Association puts the usual allowance at 4 to 10%. A pallet holds 42 bags of 80 lb, 56 of 60 lb or 80 of 40 lb.
Concrete bag calculator FAQ
How many 80 lb bags of concrete make a yard?
45, at 0.6 cubic feet a bag; Sakrete's own estimating guide gives 45 as well.
How many 60 lb bags are in a yard?
60, at 0.45 cubic feet a bag.
How many bags for a 10 × 10 slab?
For a 10 × 10 ft slab, 4 in thick, 62 bags of 80 lb with 10% extra.
Related calculators
Sources
Bag yields, pallet counts, thickness and extra on this page come from these documents, checked 8 November 2026.
- Quikrete, Concrete Mix No. 1101 data sheet, revised October 2022
- Quikrete, Concrete Mix 1101 product page
- Sakrete, High-Strength Concrete Mix page and technical data sheet
- Sakrete, Estimating Bagged Concrete Jobs
- NRMCA, CIP 31 Ordering Ready Mixed Concrete
- NRMCA, CIP 8 Discrepancies in Yield
- Quikrete project sheet, Concrete Driveways and Curbs
- Quikrete project sheet, Concrete Sidewalks and Small Slabs
- Quikrete project sheet, Concrete Patios
- 2025 California Residential Code, section R506.1 (IRC based)
- Sonoco, Sonotube Round brochure
- Sonoco, Sonotube Concrete Forming Products brochure
- Jefferson County, Missouri, ready-mix bid tabulation, February 2020
- Grannas Bros., ready-mix calculator page
- Vertigraph, How to Calculate Concrete Yardage