How this calculator works
The calculator uses your tile size and joint width to estimate total grout joint volume, converts it to dry bag weight using an industry-calibrated density factor, and adds a 10% waste allowance for squeeze-out and cleanup.
(2×12)/12² × 0.1875 × 0.375 × 38 × 100 × 1.10 = ≈50 lbs → 2 bags.
Sanded vs. unsanded grout
Use sanded grout for joints 1/8" and wider — the sand prevents cracking as the joint cures. Use unsanded grout for joints narrower than 1/8", or for soft natural stone (marble, limestone) where sand would scratch the face.
Frequently asked questions
How much grout do I need for 100 square feet?
For standard 12"×12" tile with a 3/16" joint, expect about 2 bags (25 lb each) of sanded grout. Smaller tiles or wider joints require significantly more — 4"×4" mosaic with a 3/16" joint uses roughly 6 bags per 100 sq ft.
How many square feet does a bag of grout cover?
A 25 lb bag of sanded grout covers roughly 50–65 square feet for 12"×12" tile with a standard 3/16" joint. Coverage drops sharply with smaller tiles or wider joints.