Grout Calculator
Grout Coverage Reference Chart
Approximate pounds of grout per 100 sq ft with 1/8" grout lines.
| Tile Size | Tile Thickness | Lbs per 100 sq ft | 25-lb Bags per 100 sq ft |
|---|---|---|---|
| 4" × 4" | 1/4" | 18.8 | 1 |
| 6" × 6" | 1/4" | 12.5 | 1 |
| 12" × 12" | 3/8" | 9.4 | 1 |
| 12" × 24" | 3/8" | 7.0 | 1 |
| 18" × 18" | 3/8" | 6.3 | 1 |
| 24" × 24" | 3/8" | 4.7 | 1 |
How We Calculate This
This grout calculator uses established formulas and industry-standard data to provide accurate estimates.
- Enter your specific values into the calculator fields above
- Our algorithm applies the relevant formulas using your inputs
- Results are calculated instantly in your browser — nothing is sent to a server
- Review the detailed breakdown to understand how each factor affects your result
These calculations are estimates based on standard formulas. For critical decisions, always consult a qualified professional.
How to Convert Oven Recipes to Air Fryer
Grout fills the joints between tiles. The amount needed depends on tile size (which determines joint length per square foot), joint width, and tile thickness (joint depth).
The basic rule:
- Measure your tile dimensions and choose your grout line width — 1/8" is standard for most floor and wall tiles
- The grout joint depth equals the tile thickness — thicker tiles need more grout
- Order 10-20% extra grout to account for waste, cleanup, and variations in joint depth
This calculator uses the industry-standard formula based on tile perimeter, joint cross-section, and a grout density of approximately 100 lbs per cubic foot. Sanded grout is used for joints 1/8" and wider; unsanded grout for joints under 1/8".
When Would You Use This Calculator?
This grout calculator is designed for anyone who needs quick, reliable estimates without complex spreadsheets or professional consultations.
- When you need a quick estimate before committing to a purchase or project
- When comparing different options or scenarios side by side
- When planning a budget and need to understand potential costs
- When you want to verify a quote or estimate you've received from a professional
- When teaching or learning about the concepts behind these calculations
Frequently Asked Questions
How much grout do I need for 100 square feet of tile?
It depends on tile size and joint width. For 12×12 tiles with 1/8" grout lines, you'll need roughly 7-10 lbs of grout for 100 sq ft. For 6×6 tiles with the same joints, about 15-18 lbs. Smaller tiles and wider grout lines require significantly more grout.
What's the difference between sanded and unsanded grout?
Sanded grout contains fine sand particles and is used for grout joints 1/8" and wider. The sand adds strength and prevents cracking in wider joints. Unsanded grout is smooth, used for joints under 1/8", and is preferred for polished marble and soft stone tiles that could be scratched by sand.
How many square feet does a 25-lb bag of grout cover?
A 25-lb bag of sanded grout typically covers 100-250 sq ft for 12×12 tiles with 1/8" joints, or 50-100 sq ft for 6×6 tiles. Coverage decreases with smaller tiles, wider joints, and thicker tiles. Always check the manufacturer's coverage chart on the bag.
Can I mix different bags of grout?
Yes, but always mix bags from the same lot/batch number for color consistency. Mix all the grout you need for a visible area at once if possible. Different production batches can have slight color variations that become noticeable once dried.
How long does grout take to dry?
Grout typically needs 24-72 hours to fully cure before exposing it to moisture. Initial set happens in 15-30 minutes. You can usually walk on grouted floors after 24 hours. Wait at least 72 hours before sealing. Full strength is reached in about 28 days.
Should I seal my grout?
Yes, sealing grout is highly recommended for all cement-based grout, especially in kitchens, bathrooms, and entryways. Sealer prevents staining, moisture penetration, and mold growth. Apply sealer after grout has cured (7-28 days) and reapply every 1-2 years. Epoxy grout does not need sealing.