Last updated: October 2026
How much grout do I need? Calculate it exactly
Short answer: enter your tile size, grout joint width, joint depth and total area above — the calculator tells you the grout needed in pounds, kilograms and bag count, with a waste allowance built in. No signup, nothing leaves your browser.
How the math works
Grout fills the joints around every tile. The calculator figures out how many tiles cover your area, computes the joint volume per tile from joint width × depth × tile perimeter, and converts volume to weight using standard mixed-grout density — then adds your waste percentage and rounds up to whole bags. Small tiles need much more grout per square foot than big ones, because there are more joints — the math handles that automatically.
Sanded vs unsanded grout
Use unsanded grout for joints under 1/8 inch (it won't scratch tile), and sanded grout for 1/8 inch and wider (the sand stops shrinkage and cracking). Epoxy grout is the premium option — stain-proof and toughest, but harder to work with. The weight math is the same either way.
Frequently asked questions
How much grout do I need for my tile project?
Enter your tile length and width, grout joint width, joint depth and total area above. The calculator returns the grout needed in pounds and kilograms plus how many 25 lb or 10 lb bags to buy, with a waste allowance included.
How wide should grout joints be?
1/16 inch for rectified (precisely cut) tile, 1/8 inch is the most common for wall and floor tile, 3/16 to 1/4 inch for larger or rustic tile. Use sanded grout for joints 1/8 inch and wider; unsanded for narrower.
How deep should grout joints be?
Grout should fill the joint to roughly the full tile thickness — the calculator defaults joint depth to your tile thickness. For 3/8 inch thick tile, that's a 3/8 inch deep joint.
How many square feet does a 25 lb bag of grout cover?
It depends on tile size and joint width. For 12x12 inch tile with 1/4 inch joints, a 25 lb bag covers roughly 150-170 sq ft. Small tiles with the same joint width need much more grout per square foot because there are more joints.
Should I add extra grout for waste?
Yes — 10% is the standard allowance and it's the calculator's default. Bump it to 15% for diagonal layouts, mosaics or first-time DIY tiling.