There is no honest single figure for grout coverage — it swings by a factor of five between a large floor tile with a thin joint and a small mosaic with a wide one. So we do not publish an average. We ask for the four things that decide it and compute the volume.
Enter the area, then your tile size, thickness and joint width. The formula is shown in the workings so you can check it.
Works in metric and US imperial — you choose at the start and can switch at any time. Every figure this calculator uses is published with its source, and the result comes with a printable order sheet. No account, no email, and nothing you type leaves your browser.
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Because coverage swings by a factor of five between a large floor tile with a thin joint and a small mosaic with a wide one. Publishing an average would be publishing a number that is wrong for nearly everyone. So this page derives it from your tile size, thickness and joint width instead — and shows the formula in the workings so you can check it.
(L + W) ÷ (L × W) gives the metres of joint per square metre; multiply by joint width and tile thickness for the volume, then by density for the weight. For 300 × 300 mm tiles, 8 mm thick, with a 3 mm joint, that is 6.7 m of joint per square metre and about 0.26 kg of grout per m² — so a 20 m² floor needs roughly a 5 kg bag. Swap in 50 mm mosaic at the same joint and the figure is more than four times higher.
Most wall grouts are rated to about 3 mm; floor and wide-joint grouts go to 20 mm and contain sand. Using a narrow-joint grout in a wide joint cracks it. Two other things worth getting right before you open a bag: let the adhesive cure first, usually 24 hours and longer in cold or on a non-porous substrate, because grouting early traps moisture and causes patchy colour; and seal porous tiles, since natural stone and unglazed porcelain take up pigment and stain permanently.
It depends entirely on tile size and joint width — the range spans a factor of five, which is why no honest single figure exists. For 300 by 300 mm tiles 8 mm thick with a 3 mm joint it is about 0.26 kg per m2; for 50 mm mosaic it is more than four times that.
(L + W) divided by (L times W) gives metres of joint per square metre. Multiply by joint width and tile thickness for the volume, then by grout density for the weight. We default to 1,600 kg/m3, typical for a cement-based grout; epoxy is heavier.
No. Most wall grouts are rated to about 3 mm; floor and wide-joint grouts go up to 20 mm and contain sand. A narrow-joint grout used in a wide joint will crack.
Never. Perimeters, changes of plane, and any run over about 8 m need a flexible sealant. Grouting them solid is why tiles tent and crack later.