What is a Tile Grout Calculator?
A tile grout calculator determines the volume of grout needed to fill the joints between tiles. By considering tile dimensions, joint width, tile thickness, and total coverage area, this calculator ensures you purchase the correct amount of grout—avoiding waste from over-buying or delays from under-estimating.
Accurate grout estimation saves money and time. Grout comes in pre-mixed bags or powder that must be measured precisely. Running out mid-project can be problematic because color batches vary slightly, potentially creating visible differences in grout lines. This calculator prevents those issues while helping you budget your tile project accurately.
Understanding Grout Joint Width
Grout joint width affects both aesthetics and structural performance. Wider joints are more forgiving of tile size variations but use more grout and collect more dirt. Narrower joints create a seamless modern look but require perfectly sized tiles.
Standard Joint Width Guidelines
- 1/16": Rectified tiles only, modern minimal look
- 1/8": Most common, standard for floor and wall tiles
- 3/16": Handmade or slightly irregular tiles
- 1/4": Rustic tiles, highly textured surfaces
- 3/8" to 1/2": Large format tiles, brick-style layouts
Sanded vs. Unsanded Grout
Sanded Grout
Contains fine sand particles that provide strength and prevent shrinkage in wider joints. Use for joints 1/8" and wider.
- Best for floor tiles and wider joints
- More durable and crack-resistant
- Less expensive than unsanded
- Can scratch polished marble, glass, or metal tiles
- Available in more colors
Unsanded Grout
Smooth grout without sand, ideal for narrow joints and delicate tiles. Use for joints narrower than 1/8".
- Best for wall tiles and narrow joints
- Won't scratch polished or delicate surfaces
- Easier to work into narrow joints
- Can shrink in wider joints, causing cracks
- More expensive per pound
Epoxy Grout
Premium grout made from epoxy resins instead of cement. Waterproof, stain-resistant, and extremely durable.
- Ideal for wet areas (showers, pools)
- Stain and chemical resistant
- Never needs sealing
- 3-4 times more expensive
- Difficult to work with, short working time
Grout Coverage Rates
Grout coverage varies based on tile size and joint width. Manufacturers provide coverage charts, but our calculator accounts for all variables to give you an accurate estimate.
| Tile Size | Joint Width | Coverage per lb |
|---|---|---|
| 4" × 4" | 1/8" | 50-60 sq ft |
| 12" × 12" | 1/8" | 100-120 sq ft |
| 12" × 24" | 1/16" | 150-180 sq ft |
| 24" × 24" | 1/8" | 120-140 sq ft |
Grout Application Tips
Preparation
- Wait 24-72 hours after setting tiles before grouting
- Remove all tile spacers
- Clean joints thoroughly—no thinset residue
- Ensure tiles are dry (moisture causes discoloration)
- Seal natural stone before grouting to prevent staining
Mixing
- Add powder to water, not water to powder
- Mix to peanut butter consistency
- Let slake (rest) for 10 minutes, then remix
- Don't add water after slaking
- Mix only what you can use in 30 minutes
Application
- Hold float at 45° angle
- Force grout diagonally across joints
- Work in 10-20 sq ft sections
- Scrape off excess with float at 90° angle
- Wait until grout begins to firm (hazy appearance)
- Sponge clean with circular motions
- Change water frequently—dirty water leaves haze
Common Grouting Mistakes
Adding Too Much Water
Thin grout is weaker and more prone to cracking. It may also cause color variations. Mix to manufacturer's specifications and never add water after the slaking period.
Grouting Too Soon
Grouting before thinset fully cures can cause tiles to shift. Wait at least 24 hours (72 hours for large format tiles or in humid conditions) before grouting.
Not Compacting Grout
Voids in grout joints weaken the installation and allow water penetration. Force grout firmly into joints, ensuring complete filling.
Cleaning Too Soon
Wiping while grout is still soft pulls it from joints. Wait until grout is firm but not hard—it should feel rubbery when touched.
Skipping Sealer
Unsealed cement-based grout absorbs stains and moisture. Seal grout 2-3 weeks after installation, once fully cured. Reapply annually in high-traffic areas.
Grout Color Selection
Grout color dramatically affects the overall appearance of your tile installation:
- Matching grout: Makes tiles appear as one continuous surface, emphasizes tile rather than pattern
- Contrasting grout: Highlights tile pattern and geometry, more dramatic look
- Light grout: Shows dirt easily, requires more maintenance
- Dark grout: Hides dirt, more forgiving, modern aesthetic
- Gray grout: Most versatile, works with most tile colors
Frequently Asked Questions
How much grout waste should I plan for?
Add 10-15% extra for waste, spills, and mixing errors. If you're new to tiling, add 20-25% since you'll likely remix batches that dry out.
Can I use wall grout on floors?
No. Floor grout must be sanded and more durable to withstand foot traffic and cleaning. Wall grout is often unsanded and less resistant to wear.
How long does grout take to dry?
Grout is usually dry to touch in 24 hours but takes 72 hours to cure enough for light traffic. Full cure time is 28 days. Avoid heavy traffic and cleaning during this period.
Should grout lines be filled to the top?
No. Grout should be slightly recessed (about 1/32" to 1/16" below tile surface). This prevents wear on high points and creates shadow lines that hide slight variations.
Can I change grout color later?
You can apply grout stain or colorant to change color, but it requires thorough cleaning and multiple coats. It's a band-aid solution—replacing grout gives better, longer-lasting results.
What's the difference between grout and caulk?
Grout is rigid and used in field tiles. Caulk is flexible and used where tiles meet different materials (bathtubs, sinks, corners) because these areas expand and contract. Never grout corners—always caulk them.