How many bags of concrete do I need for a 10x10 slab?
A bag count is the whole job on a small slab. Buy too few and the pour stops mid slab. Buy too many and you haul heavy bags back to the store. This guide gives the count for the most asked slab of all, the 10 by 10, and shows the math so any size takes seconds.
The short answer
For a 10 by 10 foot slab at 4 inches thick, buy 62 bags of 80 lb concrete mix, or 82 bags of 60 lb. At 6 inches thick, buy 92 bags of 80 lb, or 123 bags of 60 lb. Every count on this page includes 10 percent waste, the same line the calculator adds.
| 10 by 10 slab | Bags of 80 lb | Bags of 60 lb |
|---|---|---|
| 4 inches thick | 62 bags | 82 bags |
| 6 inches thick | 92 bags | 123 bags |
The count, step by step
Length times width gives the area in square feet. A 10 by 10 slab covers 100 square feet. Measure the inside of the forms, where the concrete will sit.
Length x Width = AreaMultiply the area by the thickness in feet. Four inches is one third of a foot, so this slab holds 33.33 cubic feet of concrete.
Area x Thickness = Cubic FeetAdd 10 percent for spill, uneven ground and the last thin corner of the pour. The order volume grows from 33.33 to 36.67 cubic feet.
Cubic Feet x 1.10An 80 lb bag yields 0.60 cubic feet. A 60 lb bag yields 0.45. Divide the order volume by the yield and round up. 36.67 divided by 0.60 gives 62 bags.
Order Volume / Yield = BagsBags add up fast. 62 bags of 80 lb weigh 4,960 pounds in total. Plan the truck trips and the help before you plan the pour.
Bags x Bag Weight = Carry WeightSet the bags around the forms before the first mix lands. A 62 bag pour moves fast, and hunting for bags mid pour leaves a weak seam where two batches met.
Bags by the FormsThe other two bag sizes
The chart runs the two big sizes. Stores stock two more, and the same math counts them.
40 lb bags
The small bag yields 0.30 cubic feet, so this slab takes 123 of them at 4 inches thick. Small bags suit solo work and small mixers. The count is honest, but the hauling is long.
50 lb bags
The middle bag yields 0.375 cubic feet, so the count for this slab lands at 98 bags. It splits the difference: fewer trips than the 40 lb size, a kinder lift than the 80 lb size.
Bag counts for common slab sizes
| Slab size | Thickness | Bags of 80 lb | Bags of 60 lb |
|---|---|---|---|
| 4 by 8 ft | 4 in | 20 bags | 27 bags |
| 8 by 8 ft | 4 in | 40 bags | 53 bags |
| 10 by 10 ft | 4 in | 62 bags | 82 bags |
| 10 by 12 ft | 4 in | 74 bags | 98 bags |
| 12 by 12 ft | 4 in | 88 bags | 118 bags |
| 8 by 8 ft | 6 in | 59 bags | 79 bags |
| 10 by 10 ft | 6 in | 92 bags | 123 bags |
| 12 by 12 ft | 6 in | 132 bags | 176 bags |
When a ready mix truck beats bags
Bags and trucks pour the same concrete. The right pick turns on job size, and the size line sits close to this slab.
The one yard line
Bagged mix suits jobs under about 1 cubic yard. The 10 by 10 at 4 inches sits at 1.36 yards with waste, just past that line. At 6 inches it reaches 2.04 yards, and ready mix starts to win on work and on time.
What the truck changes
A truck pours the whole slab in minutes, so the surface stays even and the finish window stays calm. Bags pour in batches, and on a big slab the first batch can start to set before the last one lands. Small jobs flip the story: a walkway pad or a shed base under a yard mixes fast, and no truck minimums apply.
The weight test
62 bags of 80 lb weigh 4,960 pounds. 92 bags weigh 7,360 pounds. If the carry weight scares you, the job is telling you its answer. Either split the pour into small sections you can mix, or book the truck.
Common mistakes
The same 10 by 10 slab needs 56 bags with no waste and 62 with it. The no waste count runs out near the last corner, where a thin spot hurts the slab most.
An 80 lb bag covers more per bag, but a 60 lb bag lifts easier. The lighter or cheaper route stays hidden until you count both sizes side by side.
The count is only half the plan. 62 bags of 80 lb weigh 4,960 pounds, and every bag rides in a truck bed and then gets carried to the forms by hand.
Bags suit small pours. A slab past 2 cubic yards mixed by hand means hours of work while the first batch sets. That is truck work.
Questions, answered
How many bags of concrete do I need for a 10x10 slab?
At 4 inches thick with 10 percent waste, buy 62 bags of 80 lb. The same slab takes 82 bags of 60 lb or 123 bags of 40 lb.
How many bags of concrete make a cubic yard?
One cubic yard holds 27 cubic feet, so 80 lb bags at 0.60 cubic feet each fill it with 45 bags and no waste counted. Add the 10 percent waste line and the buy count is 50 bags.
Can I mix two bag sizes on one slab?
Yes. The mix inside is the same family of concrete. Count the full job in one size first, then swap part of the count if the store runs short on your size. Keep the total yield the same: one 80 lb bag equals one and a third 60 lb bags by volume.
How much do 62 bags of 80 lb concrete weigh?
4,960 pounds in total. That is just under 2.5 tons of dry mix, and every pound moves by hand twice, once at the store and once at the slab.
When should I order ready mix instead of bags?
Bags suit pours under about 1 cubic yard. Past 1.5 to 2 cubic yards, a ready mix truck usually costs less and pours in minutes. The 10 by 10 slab at 6 inches thick holds 2.04 yards with waste, so it sits in truck land.
Run your own slab size
Your slab is not 10 by 10? The concrete bag calculator takes any length, width and thickness. It counts all four bag sizes at once, with carry weight and cost when you add a price.