Mix bags, formwork, reinforcement, sealer and cost for a poured concrete countertop.
Estimates are planning aids, not a professional quote. Double-check quantities and product coverage — and any local code or permit requirements — before you buy.
⚠ The corners around a sink or cooktop cutout are the weakest point in the pour — extra fiber or a strip of mesh folded into that corner keeps it from cracking when the slab is lifted.
⚠ Demold in 24–48 hours, but hold off setting or loading the top for a full 7 days and let it cure a further three weeks before sealing for daily kitchen use — concrete keeps gaining strength for about 28 days.
| Countertops | $281–$380 |
| Lumber & Decking | $82–$110 |
| Finishing & Sealant | $77–$105 |
| Membrane & Fabric | $53–$72 |
| Fasteners & Hardware | $15–$21 |
| Total | $508–$687 |
Excludes tools, delivery, tax and permit fees. Labor not included — this is a DIY materials estimate.
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About this calculator
Enter your counter run, depth and slab thickness, and the Concrete Countertop Calculator sizes the actual pour — mix bags by cubic foot, the melamine mold it takes to form it, the reinforcement grid, and the sealer and cure supplies to finish it. This is a poured product, not a slab you shop for by the square foot, so the whole takeoff runs off volume and mold geometry instead.
Drop the thickness below about 1.75 inches and the calculator switches the mix and the reinforcement together, from a standard bagged mix with steel wire mesh to a lighter GFRC-style mix with glass-fiber scrim, because a thin pour doesn't leave enough concrete cover to bury steel safely. Choose an edge profile, add sink cutouts, and pick cast-in-place or precast-and-flip to match how you'll actually build the mold.
Step by step
A step-by-step walkthrough to go with your plan above. Follow the product instructions and any local code or permit requirements as you work.
Measure the run and depth, decide your thickness and edge profile, and mark sink and cooktop cutouts from their actual templates. The calculator turns those into a bag count and a mold cut list.
Cut a deck sized to the counter plus a working margin, screw side forms on edge around the perimeter at the slab's thickness, and add the edge-profile liner if you're not going square. Caulk every inside seam.
Wax every mold surface the concrete will touch, cut reinforcement to fit a couple inches in from the edges, and set foam knockouts for any sink or cooktop cutout, sealed so mix can't creep underneath.
Mix in small batches to the mix maker's water ratio — too much water is the single most common failure — and place it working from one end, packing it into corners and around cutouts and reinforcement.
Run a sander or vibrator against the outside of the mold to walk trapped air bubbles to the surface, then strike the top flush with a straightedge dragged across the form tops.
Cover it and keep it damp (or apply a spray cure-and-seal) and leave it in the mold at least 24–48 hours before demolding, then let it keep curing, undisturbed, for a full week before it takes any load.
Unscrew and lift the forms away, then flip a precast slab onto its cabinets with help or a lifter — never before it's fully cured. Fill any pinholes and sand the edges smooth.
Hand-trowel a satin finish or wet-polish through a diamond pad sequence for a ground look, then apply a penetrating densifier followed by a food-safe topical sealer once the slab has cured a full month.
Equip the job
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Keep planning
Interior & Finishing
Answers
Multiply the run length by the depth to get square footage, then by the slab thickness in feet to get cubic feet — an 8-foot run at 25 inches deep and 1.5 inches thick is a little over 2 cubic feet of actual poured concrete. Add a spillage allowance for topping off the mold and pulling a test sample or two, then convert to bags off the mix's stated yield. This calculator does that math and rounds to whole bags of the mix your thickness calls for.
Only if the slab is thick enough to bury it safely. Standard concrete at 2 inches or more takes a wire mesh or light rebar grid centered in the pour. Thinner slabs, especially the popular 1.25–1.5 inch look, don't leave enough cover on both faces for steel, so they're cast in a GFRC-style mix reinforced with alkali-resistant glass fiber mesh instead, which won't rust or telegraph through the finished face.
Build a mold from 3/4-inch melamine-faced particleboard: a flat deck sized to the counter with a few inches of working margin, and side forms ripped to the slab's thickness screwed on edge around the perimeter. Caulk every inside seam with neutral-cure silicone so it doesn't leak, wax every surface the concrete will touch, and brace it dead flat and level before you pour — a mold that isn't flat casts a countertop that isn't either.
You can usually pull it from the mold in 24 to 48 hours, but hold off setting it on cabinets or loading it for a full week, and wait about a month before sealing it for daily use. Concrete keeps gaining strength for around 28 days, and sealing too early traps moisture under the finish instead of letting it fully cure out.
Precasting off the cabinets and flipping it once cured gives a smoother top face (the mold-side face becomes the finished surface) and lets you build the mold on sawhorses instead of over your cabinets, but a solid slab is heavy and the flip takes at least two people or a proper lifter. Casting in place skips the flip and the transport risk but means sealing the mold tight against the walls and living with a hand-finished top face.