How many bags of concrete for a countertop?
A 10 foot run of countertop, 25½ inches deep and 1½ inches thick, covers 21.25 square feet and needs 2.66 cubic feet of mix. With 15% extra that is 6 bags of 80 lb countertop mix, and the finished top weighs about 372 pounds.
How to work it out
- 120 in × 25.5 in = 21.3 sq ft
- 21.3 sq ft × 1.5 in = 2.66 cu ft + 15% = 3.05 cu ft
- ÷ 0.6 cu ft per 80 lb bag = 6 bags
Ten feet of base cabinets with a standard depth is a typical kitchen wall run, and it shows how few bags a countertop really takes — the hard part is the forms and the finishing, not the quantity.
Adjust for your project
More options: Extra
- Countertop area
- 21.3 sq ft
- Mix needed (incl. extra)
- 3.05 cu ft (0.11 cu yd)
- Finished weight (about 140 lb per cu ft)
- 372 lb (0 tons)
- Weight per square foot
- 17.5 lb
- Most countertop cabinets carry a concrete top, but check long overhangs, islands and old or frameless cabinets — and plan how you will lift a precast piece into place.
10 ft countertop run by thickness (15% extra)
| Thickness | Countertop mix bags | Finished weight (about 140 lb per cu ft) |
|---|---|---|
| 1.5 in | 6 bags | 372 lb |
| 2 in | 7 bags | 496 lb |
| 2.5 in | 9 bags | 620 lb |
| 3 in | 11 bags | 744 lb |
Why only six bags
At 1½ in, each 80 lb bag of countertop mix covers about 4.8 sq ft, so 21.25 sq ft takes 4.4 bags. The 15% allowance (thin pours lose a lot to the mixing bucket, the drill paddle and overfilled edges) brings it to 5.1, so buy 6. A drop-in sink cutout of around 3.5 sq ft saves less than a bag; leave it in the count and use the spare for a test piece.
The finished run weighs about 372 lb, or 17.5 lb per square foot. Cast in one piece, that is a job for four people and a plan for getting it through the door. Many people cast it in two 5 ft pieces instead, each under 190 lb, and join them with a tight seam over a cabinet partition.
Thicker tops and islands
At 2 in the same run takes 7 bags and weighs about 496 lb. An island adds fast: a 6 × 3 ft island at 1½ in is 18 sq ft, another 5 bags and 315 lb, and its overhang needs support underneath. Use the rows above to add every piece. Once it has cured, seal it — the concrete sealer calculator shows how coverage per gallon works — and check the weight against your cabinets with the concrete weight calculator.
Different size? Use the full Concrete Countertop Calculator.
What you’ll need
- Concrete countertop mixMid-range price
A fine, high-strength mix made for thin, flat pieces with crisp edges. Check its yield on the bag.
See options on Amazon (opens in a new tab) - Drill mixing paddleBudget price
Mixes mortar, self-leveler, stucco and grout in a bucket. Use a low-speed, high-torque drill so the mix doesn’t fly.
See options on Amazon (opens in a new tab) - Concrete countertop sealerMid-range price
Protects a countertop from stains and acids. Read the label for food-contact use and recoat timing.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
How many bags of concrete for a countertop 2 inches thick?
7 bags of 80 lb for the same 10 foot run, weighing about 496 pounds.
How much does a 6×3 ft concrete island top weigh?
About 315 pounds at 1½ inches thick (5 bags of 80 lb mix).
How many bags for a 5 foot bathroom vanity top?
3 bags of 80 lb at 1½ inches, about 160 pounds finished.
Sources
- Quikrete Countertop Mix (No. 1106) data sheet (opens in a new tab) — Each 80 lb bag yields about 0.6 cu ft; 2,000 psi at 24 hours, 4,000 at 7 days, 6,000 at 28 days.
- Quikrete Concrete Mix (No. 1101) data sheet (opens in a new tab) — Yields: 40 lb ≈ 0.30, 50 lb ≈ 0.375, 60 lb ≈ 0.45, 80 lb ≈ 0.60, 90 lb ≈ 0.675 cu ft; unit weight ≈ 140 lb/cu ft; for pours 2 in thick or more; 6–9 pints of water per 80 lb bag; control joints every 6–8 ft; cure 5 days at 70 °F or above, 7 days at 50–70 °F; protect from freezing for 48 hours.