How the grout calculator works
The coverage formula
Grout fills the joints between tiles: perimeter × width × depth per tile, summed over the count. Small tiles explode the math (a mosaic floor has 10× the joint length of a 12" floor at the same area) — which is why mosaics eat grout by the bag while large-format tiles sip it. The calculator runs the true formula rather than a rule of thumb, because tile size swings the answer enormously.
Sanded vs unsanded, settled
Sanded grout (joints ≥1/8") is stronger and cheaper — the standard for floors and most walls. Unsanded (under 1/8") squeezes into narrow joints without scratching — required for glass tile, polished marble, and vertical Tight-joint installs. Epoxy grout is the premium third option: stain-proof and nearly unbreakable, at triple the price and half the working time.
The seal-and-maintain step
Cement grout is porous; sealed grout repels the wine, coffee, and grease that unsealed grout drinks. Sealer goes on 72 hours after grouting, re-annually in wet areas. The alternative is epoxy grout, which skips sealing entirely — a legitimate choice for busy kitchens despite the cost and pace.