How to use the concrete bag calculator
- Choose what you are filling. Pick a slab or pad, a round post hole or tube, or a known volume in cubic feet, cubic yards or cubic metres.
- Enter the size and the bag size. Type the dimensions. Then choose the bag you plan to buy: 40 lb, 50 lb, 60 lb or 80 lb. For several holes of the same size, enter how many.
- Read the number of bags. The result shows the bags to buy in your size, the count in the other three sizes, and how much the bags weigh.
What is a concrete bag calculator?
A concrete bag calculator is a tool that turns a volume of concrete into a number of bags of pre-mixed concrete. It divides the volume by the yield of one bag, which is the volume of mixed concrete the bag makes, and rounds up to a full bag.
Bagged concrete mix is also called sack concrete, bagged cement or premix. The bag holds cement, sand and stone. You add only water.
Features
- Bag counts for 40 lb, 50 lb, 60 lb and 80 lb bags, with one size as the main answer
- Three inputs: a slab or pad, a round post hole or tube, or a volume you already know
- A count field for several holes or pads of the same size
- The dry weight of the bags you have to carry
- Full pallets and loose bags for 40 lb, 60 lb and 80 lb bags
- A cost from your own price per bag
- An adjustable waste allowance
- A live 3D preview, a PDF of the estimate and a WhatsApp share button
What you can use it for
- Setting fence posts, mailbox posts and deck posts
- A small pad for an air conditioner, a grill or a step
- Filling a round form tube for a pier
- Any job too small for a ready-mix truck
- Comparing how many 40, 50, 60 or 80 lb bags a job takes
How the number of bags is calculated
Bags = volume to order in cubic feet ÷ yield of one bag in cubic feet, rounded up to a full bag.
| Bag size | Yield per bag | Bags per cubic foot | Bags per cubic yard | Area one bag covers at 4 inches |
|---|---|---|---|---|
| 40 lb | 0.30 cubic feet | 3.33 | 90 | 0.9 sq ft |
| 50 lb | 0.375 cubic feet | 2.67 | 72 | 1.13 sq ft |
| 60 lb | 0.45 cubic feet | 2.22 | 60 | 1.35 sq ft |
| 80 lb | 0.60 cubic feet | 1.67 | 45 | 1.8 sq ft |
The yields are the approximate values in the Quikrete Concrete Mix data sheet (product 1101, revised October 2022). The other columns are worked out from the yield. Quikrete's Fast-Setting Concrete Mix (product 1004) data sheet gives the same 0.375 cubic feet for a 50 lb bag and 0.45 for a 60 lb bag. Another mix can yield a different amount, so check the yield printed on the bag you buy.
For a full table by bag size, see the guide to bags per cubic yard.
Worked example: a 4 ft by 4 ft pad, 4 inches thick
- Volume: 4 ft × 4 ft × 0.333 ft = 5.33 cubic feet.
- With 10% waste: 5.33 × 1.10 = 5.87 cubic feet.
- In 80 lb bags: 5.87 ÷ 0.60 = 9.8, so 10 bags.
- In 60 lb bags: 5.87 ÷ 0.45 = 13.04, so 14 bags.
- Ten 80 lb bags weigh 800 lb before water is added.
These are the numbers the calculator shows when the page opens.
How many bags are on a pallet
Quikrete's own product page for Concrete Mix (product 1101) lists these pallet sizes. It gives no pallet count for the 50 lb bag and no weight for the empty pallet.
| Bag size | Bags per pallet | Weight of the bags on one pallet | Concrete from one pallet |
|---|---|---|---|
| 40 lb | 80 | 3,200 lb | 24 cubic feet (0.89 cubic yards) |
| 60 lb | 56 | 3,360 lb | 25.2 cubic feet (0.93 cubic yards) |
| 80 lb | 42 | 3,360 lb | 25.2 cubic feet (0.93 cubic yards) |
The last two columns are worked out: bags × bag weight, and bags × the yield of one bag. The weight is the bags only; the wooden pallet adds to it. One cubic yard needs 45 bags of 80 lb, so it is slightly more than one full pallet of 42 bags.
The calculator shows the full pallets and the loose bags for your job under the bag counts. More on pallet sizes and weights is in the guide to bags on a pallet.
Bags for a post hole
A post hole is a cylinder. Its volume is π × (diameter ÷ 2)² × depth. A hole 10 inches across and 30 inches deep holds 1.36 cubic feet. With 10% waste that is 1.5 cubic feet, which is 3 bags of 80 lb or 4 bags of 60 lb.
The calculator fills the whole hole. It does not subtract the space the post takes, so the real amount is a little lower. For a row of posts, enter the number of holes.
What the calculator includes
- The calculator has four bag sizes. A 90 lb bag is in the same data sheet but is sold only in some regions, so it is not included.
- The post is not subtracted from a post hole.
- Each dimension can be up to 10,000 in its unit, and a volume up to 1,000,000. The count can be 1 to 1,000 and waste 0 to 50%.
- The weight shown is the dry weight of the bags. The mixed concrete is heavier because of the water.
Is it private?
Yes. The calculation and the PDF are made in your browser. The numbers you type are not sent to our server and are not saved.
Tips for an accurate estimate
- Compare the bag counts for each size. Fewer heavy bags mean less tearing and mixing, more light bags are easier to carry.
- Read the yield printed on your bag. If it differs from the figure on this page, the bag count changes in proportion.
- Buy full pallets when the count is close to one; the calculator shows the pallets and the loose bags.
- Keep one or two extra bags for spills and low spots, and return unopened ones if the store allows it.
- Mix one bag at a time with the water amount on the bag, so every batch has the same strength.
Related calculators
Frequently asked questions
- How many bags of concrete do I need?
- Divide the volume in cubic feet by the yield of one bag and round up. An 80 lb bag yields about 0.60 cubic feet and a 60 lb bag about 0.45 cubic feet. A 4 ft by 4 ft pad that is 4 inches thick needs 10 bags of 80 lb with 10% waste.
- How many 80 lb bags of concrete are in a yard?
- 45 bags. A cubic yard is 27 cubic feet, and an 80 lb bag yields about 0.60 cubic feet in the Quikrete Concrete Mix data sheet.
- How many 60 lb bags of concrete are in a yard?
- 60 bags. A 60 lb bag yields about 0.45 cubic feet, and 27 divided by 0.45 is 60.
- How many 80 lb bags of concrete are on a pallet?
- 42 bags, according to Quikrete's product page for Concrete Mix (product 1101). A pallet of 60 lb bags holds 56 and a pallet of 40 lb bags holds 80.
- How much does a pallet of concrete weigh?
- The bags on a pallet of 42 bags of 80 lb weigh 3,360 lb, and 56 bags of 60 lb also weigh 3,360 lb. Add the weight of the wooden pallet itself.
- How many cubic feet are in a bag of concrete?
- It depends on the bag size. The Quikrete Concrete Mix data sheet gives about 0.30 cubic feet for a 40 lb bag, 0.375 for 50 lb, 0.45 for 60 lb and 0.60 for 80 lb.
- How many square feet does a bag of concrete cover?
- At 4 inches thick, one 80 lb bag covers about 1.8 square feet and one 60 lb bag about 1.35 square feet. A thinner pour covers more and a thicker pour covers less.
- How many bags of cement do I need?
- If you mean bags of pre-mixed concrete, this calculator gives the number in 40, 50, 60 and 80 lb sizes. Bagged concrete mix such as Quikrete Concrete Mix already contains the cement, sand and gravel, so you only add water.
- How many bags of concrete do I need for a fence post?
- It depends on the hole. A hole 10 inches across and 30 inches deep needs 3 bags of 80 lb with 10% waste, before the post is subtracted. Enter your own diameter and depth to check.
Sources
Every figure this calculator uses comes from the published sources below. The formulas are on this page, so any result can be checked by hand.
- Quikrete, Concrete Mix No. 1101: data sheet and product page. Bag yields: 0.30 ft³ (40 lb), 0.375 ft³ (50 lb), 0.45 ft³ (60 lb) and 0.60 ft³ (80 lb); bags per pallet: 80, 56 and 42.
- Quikrete, Fast-Setting Concrete Mix No. 1004: data sheet. Yields of the 50 lb and 60 lb fast-setting bags.
- Federal Highway Administration (FHWA), Report FHWA-HRT-05-057. Normal-weight concrete: 145 lb per cubic foot (1.96 tons per cubic yard).