Concrete Countertop Calculator

Total Material Cost tracks Length and Width almost proportionally -- doubling either one roughly doubles the slab's area and, with it, every material quantity -- but Mix Type is the input that actually reshapes the bill, not just its size. Mix Type 1 (standard wet-cast) and Mix Type 2 (GFRC) look like a simple heavier-vs-lighter toggle, and weight really does swing hard: a 96 in x 26 in x 1.5 in slab drops from about 283 lbs (wet-cast, with gravel and rebar) to about 119 lbs (GFRC, with AR glass fiber and acrylic polymer) -- less than half. Cost moves the OPPOSITE direction at that size: the same GFRC piece runs roughly $156 in material against about $117 for wet-cast, because glass fiber (about $8/lb) and acrylic polymer (about $6/qt) cost far more per pound than the gravel and rebar they replace, even though GFRC uses less total material and carries zero rebar. That ranking is not a universal rule, though -- it flips on small, thin pieces.

GFRC's fiber and polymer scale with the slab's VOLUME, while the rebar it eliminates is priced per linear foot of PERIMETER, so once a piece gets small enough the rebar saving outweighs the fiber premium: a 12 in x 6 in x 0.75 in sample slab costs about $3.50 in GFRC against about $7.00 in wet-cast, exactly reversing the default-size result. Check your own dimensions rather than assuming GFRC always costs more. Because Mix Type only takes the values 1 and 2, a small nudge up or down from either default rounds right back to the same setting -- you have to pick the other number outright to see wet-cast and GFRC compared. Number of Pieces scales the total material cost and every raw ingredient almost exactly linearly (10 pieces costs about 10x one piece), but it never moves Weight Per Piece or Cost Per Sq Ft -- both are already normalized to a single section, so dividing each aggregate quantity by the same piece count that produced it cancels the count out algebraically, leaving the per-unit numbers unchanged no matter how many sections you cast.