Concrete guide
How Many Bags of Concrete for a 10 x 10 Slab?
Work through concrete bag counts for a 10 x 10 slab at common thicknesses using cubic feet, yield, and waste.
Short answer
A 10 x 10 slab at 4 inches thick is 33.3 cubic feet before waste. Add a buffer, divide by the bag yield printed on the concrete mix, and round up. With 0.6 cubic feet per 80 lb bag and 10% waste, the estimate is 62 bags.
Use the Concrete CalculatorThe formula
- Cubic feet = slab length x slab width x (thickness in inches / 12)
- Buffered cubic feet = cubic feet x (1 + waste percentage)
- Concrete bags = buffered cubic feet / bag yield, rounded up
- Cubic yards = buffered cubic feet / 27
Worked example
A 10 ft by 10 ft slab at 4 inches thick
- Convert thickness: 4 inches / 12 = 0.333 ft.
- Volume before waste: 10 x 10 x 0.333 = 33.3 cubic ft.
- Add 10% for variation and waste: 33.3 x 1.10 = 36.7 cubic ft.
- Using 0.6 cubic ft per 80 lb bag: 36.7 / 0.6 = 61.2 bags.
Plan around 62 bags of 80 lb concrete mix for a 10 x 10 x 4 in slab, then confirm the selected bag yield and site conditions.
Thickness changes the answer quickly
A 10 x 10 slab is always 100 square feet, but concrete volume depends on thickness. At 3 inches it is 25 cubic feet before waste; at 4 inches it is 33.3 cubic feet; at 6 inches it is 50 cubic feet.
That thickness decision should follow the intended use, base preparation, reinforcement plan, local requirements, and product or professional guidance.
Use bag yield, not bag weight
Concrete mix bags are purchased by weight, but the calculation needs yield in cubic feet. QUIKRETE's calculator uses bag yield and rounds bag quantities up, while noting that calculations are approximate and do not account for uneven subgrade or waste.
A bag size change can alter the count even when the slab dimensions stay the same. Check the package before ordering or loading material.
- Use the cubic-foot yield from the bag you will buy.
- Round up to full bags after adding a buffer.
- Plan delivery, lifting, mixing time, water access, and help before buying many bags.
Ready-mix may be more practical
A 10 x 10 x 4 in slab with 10% buffer is about 1.36 cubic yards. For larger slabs or thick pours, compare bagged mix against ready-mix availability, minimum orders, placement timing, and equipment needs.
References and verification
Use these references together with the instructions and coverage or yield information on the product you select.