Material EngineeringStandard Coverage Formula • Exact Pounds & Bags
Grout & Mortar Calculator
Never get stuck with half-empty bags or run short mid-project. Input your tile dimensions, joint width, and square footage to calculate exact pounds of grout, 50 lb bags of thin-set mortar, and recommended trowel notch depth.
Sanded vs Unsanded SelectorTrowel Notch Coverage GuideStandard Coverage Formula
Enter Project Specifications
Includes net area plus 10–15% waste buffer
Total Grout NeededSanded Grout (Joint ≥ 1/8")
6.7 lbs
Buy 1× 10 lb bag
Formula: ((12 + 24) × 0.125" × 0.375" × 120 × 9.5) ÷ 288 = 6.7 lbs
Based on joint width ≥ 1/8″. Sand provides compressive strength and prevents shrinkage cracks.
Polymer Thin-Set Mortar50 lb Bags
4 Bags (50 lb)
~200 lbs of dry mortar mix
Provides minimum 85% bed coverage with back-buttering for large format tiles.
Mortar & Grout Mixing Rules of Thumb
01.
Add powder to water, never water to powder: Pour measured clean water into a 5-gallon bucket first, then slowly add thin-set or grout powder while mixing at low speed (under 300 RPM) to prevent entraining air bubbles.
02.
Always "Slake" for 5 to 10 minutes: After initial mixing to peanut butter consistency, let the mortar or grout sit undisturbed for 5 to 10 minutes. This allows chemical polymers to fully hydrate. Then remix briefly without adding more water.
03.
Clean sponge technique: Wash excess grout off tile faces diagonally at a 45-degree angle. Rinse your sponge frequently in clean water and wring out thoroughly; too much water washes pigment out of the grout joints.
Grout & Mortar FAQs
What is the exact formula for calculating tile grout coverage?
A standard industry coverage formula is: Grout (lbs) = [(Tile Length + Tile Width) × Joint Width × Tile Thickness × Area in Sq Ft × 9.5] ÷ (Tile Length × Tile Width). Smaller mosaic tiles with many grout joints require significantly more grout per square foot than large-format 12"×24" tiles.
How do I choose between Sanded, Unsanded, and Epoxy Grout?
Use Sanded Grout for joints 1/8" (3mm) or wider; sand aggregates prevent shrinking and cracking. Use Unsanded Grout for narrow joints under 1/8" (like 1/16" rectified tiles) and soft stone or glass tile. Choose Epoxy Grout for maximum stain resistance, mold proofing, and zero chemical degradation in steam showers and kitchen prep zones.
How do I choose the right notched trowel size for mortar?
Trowel size depends on tile size: For mosaic tiles up to 4"×4", use a 3/16" V-notch trowel (covers ~60 sq ft/bag). For tiles 4"×4" to 8"×8", use a 1/4" × 1/4" square-notch trowel (covers ~50 sq ft/bag). For tiles 8"×8" to 12"×12", use a 1/4" × 3/8" square-notch trowel (covers ~45 sq ft/bag). For large format tiles (12"×24" or larger), use a 1/2" × 1/2" square-notch or Euro-notch trowel (covers ~35 sq ft/bag) and always back-butter the tile.
Does grout need to be sealed after installation?
Yes! Standard cement-based grouts (both sanded and unsanded) are porous and absorb water, red wine, coffee, and oil. Apply a penetrating fluoropolymer grout sealer 48 to 72 hours after grouting, once the mortar and grout have fully dried. Re-apply annually for high-traffic shower floors.