Concrete · updated 2026
Concrete Countertop Calculator
Countertops are small-volume pours — a typical 8-ft run is barely 2 cubic feet — which puts them firmly in bag-mix territory, no truck needed. This concrete countertop calculator takes your counter's length, width, and thickness and returns exact concrete volume, 80-lb bag counts, and the penetrating sealer you'll need for a kitchen-safe finish, with 2026 costs. It assumes a standard 1.5-in thick cast, the DIY norm; go thicker and the weight climbs fast at ~150 lbs per cubic foot.
25 in covers a standard 24-in cabinet plus overhang
1.5–2 in is standard; thicker gets very heavy
Show the math
Volume = 8 × (25 ÷ 12) × (1.50 ÷ 12) = 2.08 cu ft
80-lb bags = 2.08 ÷ 0.6 cu ft/bag = 4 (rounded up)
Top surface = 8 × (25 ÷ 12) = 16.67 sq ft
Sealer = 16.67 ÷ 100 sq ft/quart = 1 qt (rounded up; covers 2 coats)
Cost = 4 × $6.50–$7.50/bag + 1 × $20–$35/qt
What the numbers mean
The calculator converts your measurements into a practical purchase quantity using a documented coverage or spacing assumption.
Any whole-unit quantity is rounded up so the result does not leave you short during the project.
Use the cost range as a planning baseline and confirm the final quantity, availability, and delivery charge with your local supplier.
2026 material prices
| Material | 2026 average price | Note |
|---|---|---|
| 80-lb concrete mix bag | $6.50 – $7.50 / 80-lb bag | Yields 0.6 cu ft |
| Countertop mix, 80-lb bag | $12.00 – $18.00 / 80-lb bag | Finer aggregate; fewer pinholes, less finishing |
| Penetrating sealer, quart | $20.00 – $35.00 / quart | Covers ~100 sq ft (2 coats) |
| Integral pigment, per lb | $8.00 – $15.00 / lb | About 1 lb per bag for consistent color |
Wave 1 Batch 3 content price guide, Sep 2026. 2026 U.S. national averages. Prices vary by region and retailer — confirm locally before buying.
Pro tips
- Use countertop mix, not standard mix — the finer aggregate means fewer pinholes and far less patching.
- Vibrate the forms hard: tap every side with a mallet or run a sander (no paper) along them — countertops show every trapped bubble.
- Seal twice with penetrating sealer — unsealed concrete stains within a week in a working kitchen.
- Keep thickness at 1.5–2 in; at ~150 lbs per cubic foot, a chunky 3-in counter needs serious cabinet support.
- Cure under plastic for 5–7 days before sealing — rushing the cure is how hairline cracks happen.
- An 8-ft × 25-in counter at 1.5 in needs 4 eighty-lb bags and 1 quart of sealer — one shopping trip, under $70 in materials.
Common questions
Frequently asked questions
How much concrete for an 8-ft countertop (25 in wide, 1.5 in thick)?
8 × 2.08 × 0.125 = 2.08 cu ft → 4 eighty-lb bags, plus 1 quart of sealer for the 16.7 sq ft top.
How about a 10-ft run at 2 in thick?
10 × 2.08 × 0.167 = 3.47 cu ft → 6 eighty-lb bags.
How much sealer do I need?
About 1 quart per 100 sq ft (two coats) — a single 8-ft countertop needs just 1 quart.
Countertop mix vs standard concrete mix?
Countertop mix has finer aggregate and finishes smoother; standard 80-lb bags work but need more finishing and patching.
How thick should a concrete countertop be?
1.5–2 in is standard — strong enough with reinforcement, light enough to install without a crew.
What does a DIY concrete countertop cost?
An 8-ft run: ~$26–$30 in bags plus $20–$35 in sealer — under $70 in materials before forms and reinforcement.
Related calculators
Planning estimates only. Prices are 2026 U.S. national averages and vary by region — confirm with your local supplier before buying.