Grout Calculator
Calculate grout needed for tile floors, walls, and backsplash projects
Enter Your Tile & Grout Details
Typical: 0.25"-0.5" (6-12mm)
Typical: 1/16"-1/4" (1.5-6mm)
For joints 1/8" to 1/2" - floors, countertops
Quick Answer
A 25 lb bag of grout covers approximately 50-100 sq ft depending on tile size and joint width. For 12"×12" tiles with 1/8" joints, expect about 100 sq ft per bag. Smaller tiles or wider joints need more grout.
Whether you're tiling a bathroom floor, kitchen backsplash, or shower walls, this calculator helps you determine exactly how much grout to purchase. Enter your tile dimensions and joint width to get accurate estimates in pounds and bags.
Dr. Snezana Lawrence
Mathematical Historian
15+ years experience
PhD from Yale University. Published mathematical historian ensuring precision in all calculations.
Education
PhD in Mathematical History - Yale University
Grout Types & Uses
| Type | Joint Size | Best For |
|---|---|---|
| Sanded Grout | 1/8"-1/2" | For joints 1/8" to 1/2" - floors, countertops |
| Unsanded Grout | <1/8" | For joints less than 1/8" - walls, polished tile |
| Epoxy Grout | Any | Waterproof, stain-resistant - kitchens, showers |
| Furan Grout | Any | Chemical-resistant - industrial, commercial |
Grout Coverage Chart (25 lb Bag)
| Tile Size | 1/16" Joint | 1/8" Joint | 1/4" Joint |
|---|---|---|---|
| 4" × 4" | 40 sq ft | 20 sq ft | 10 sq ft |
| 6" × 6" | 60 sq ft | 30 sq ft | 15 sq ft |
| 12" × 12" | 120 sq ft | 60 sq ft | 30 sq ft |
| 18" × 18" | 180 sq ft | 90 sq ft | 45 sq ft |
| 24" × 24" | 240 sq ft | 120 sq ft | 60 sq ft |
* Coverage based on 3/8" tile thickness. Thicker tiles require more grout.
Recommended Joint Widths
| Application | Joint Width | Notes |
|---|---|---|
| Rectified Tile (Walls) | 1/16" | Precision-cut edges, minimal joints |
| Standard Wall Tile | 1/16"-1/8" | Most common for bathrooms |
| Floor Tile | 1/8"-3/16" | Accommodates slight variations |
| Large Format (24"+) | 1/16"-1/8" | Lippage system recommended |
| Mosaic Tile | 1/8"-1/4" | Pre-mounted spacing varies |
| Outdoor/Pavers | 1/4"-1/2" | Allows for expansion |
Grouting Best Practices
- • Wait 24 hours after setting tile before grouting
- • Mix grout to peanut butter consistency
- • Work in small sections (10-20 sq ft at a time)
- • Apply grout at 45° angle to joints
- • Remove excess grout with diagonal wipes
- • Clean haze within 20-30 minutes of application
- • Avoid walking on floor grout for 24 hours
- • Seal grout after 28-day cure (cement-based only)
Frequently Asked Questions
How much grout do I need?
Calculate using: (Tile Length + Tile Width) × Joint Width × Tile Depth ÷ (Tile Length × Tile Width) × Area × 1.86 = Pounds of grout. A 25 lb bag covers approximately 50-100 sq ft depending on tile size and joint width.
How much does a bag of grout cover?
A 25 lb bag of grout typically covers 50-100 sq ft for standard floor tiles with 1/8" joints. Coverage decreases with wider joints and smaller tiles.
Should I use sanded or unsanded grout?
Use sanded grout for joints 1/8" or wider (floors, countertops). Use unsanded grout for joints under 1/8" (walls, polished marble, glass tile).
How wide should grout lines be?
Standard grout lines: 1/16"-1/8" for wall tiles, 1/8"-3/16" for floor tiles. Larger format tiles often use 1/16" joints. Mosaic tiles may have 1/8" or wider.
How long does grout take to dry?
Initial cure: 24-48 hours. Full cure: 28 days. Avoid foot traffic for 24 hours. Wait 3 days before sealing. Epoxy grout cures faster (24 hours).
Do I need to seal grout?
Yes, seal cement-based grout (sanded and unsanded) after curing to prevent stains and moisture absorption. Epoxy grout does not require sealing.
How much extra grout should I buy?
Buy 10-15% extra grout to account for waste, variations in joint width, and potential future repairs.
Can I mix different batches of grout?
Mix all bags together before starting for consistent color. Different batches may have slight color variations. Work in sections and mix small amounts at a time.
Dr. Snezana Lawrence
Mathematical Historian | PhD from Yale
Dr. Lawrence is a published mathematical historian with a PhD from Yale University. She ensures mathematical precision and accuracy in all our calculations, conversions, and academic score calculators. Her expertise spans computational mathematics and educational assessment.
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