Grout Volume Calculator
Enter tile size, joint width and depth, and area to get the exact grout volume — plus an estimate of dry grout weight and bags.
Grout fills the joints between tiles, so the volume depends on four things: the tile size, the joint width, the joint depth, and the tiled area. The published grout-coverage formula — the one behind the manufacturer coverage tables — assigns each tile a joint of length equal to its length plus its width, at the chosen width and depth, spread over the tile's face area:
grout per area = joint width × joint depth × (tile length + tile width) ÷ (tile length × tile width)
Multiply that by your tiled area and you have the grout volume. This is exact geometry, so the volume number is solid. Small tile with wide joints uses far more grout than big tile with thin joints — a `12"` tile at a `1/8"` joint uses a fraction of what a `2"` mosaic with a `1/4"` joint does.
Dry-grout weight and bag counts are estimates on top of the volume, using a typical hardened grout density. They round up and are meant for shopping; always cross-check against the coverage chart printed on the bag, which is tuned to that specific product.
grout/area = 0.125 × 0.25 × (12 + 12) ÷ (12 × 12) = 0.00521 cu in per sq in
volume ≈ 75 cu in ≈ 1.2 L → about 1 × 25 lb bag of sanded grout