Estimate grout, thinset mortar, and tile quantities for floors, walls, and backsplashes.
Complete Guide to Tile & Grout Estimation
Tiling is one of the most popular home improvement projects, and accurate material estimation is key to a smooth installation. Whether you’re tiling a kitchen backsplash, bathroom floor, or entire living area, knowing exactly how many tiles, bags of grout, and thinset mortar you need saves time and money.
Our tile and grout calculator provides instant estimates based on your area dimensions, tile size, and grout joint width. It includes a waste factor to account for cuts, breakage, and future replacement tiles.
Tile Coverage by Size
| Tile Size | Tiles per Sq Ft | Tiles per Box (typical) | Box Coverage (sq ft) |
|---|---|---|---|
| 4×4 inches | 9.0 | 80-100 | 9-11 |
| 6×6 inches | 4.0 | 44-50 | 11-12.5 |
| 12×12 inches | 1.0 | 10-15 | 10-15 |
| 12×24 inches | 0.5 | 6-8 | 12-16 |
| 24×24 inches | 0.25 | 4-5 | 16-20 |
| 3×6 (Subway) | 8.0 | 80-100 | 10-12.5 |
| 6×24 inches | 1.0 | 12-14 | 12-14 |
| 2×2 mosaic (sheet) | 36 | 10 sheets | 10 |
Grout Coverage Reference
| Tile Size | Joint Width | Grout/100 sq ft (lbs) | 25-lb Bags/100 sq ft |
|---|---|---|---|
| 4×4 in | 1/8 in | 12-15 | 1 |
| 6×6 in | 1/8 in | 8-10 | 1 |
| 12×12 in | 1/8 in | 4-6 | 1 |
| 12×12 in | 1/4 in | 8-10 | 1 |
| 12×24 in | 1/8 in | 3-4 | 1 |
| 3×6 in (Subway) | 1/16 in | 5-7 | 1 |
| 3×6 in (Subway) | 1/8 in | 10-13 | 1 |
| 24×24 in | 1/8 in | 2-3 | 1 |
Frequently Asked Questions
How much grout do I need per square foot?
Grout coverage varies by tile size and joint width. For 12×12 inch tiles with 1/8-inch joints, you need about 1 lb of grout per 20 sq ft. For 4×4 tiles with 1/8-inch joints, about 1 lb per 8 sq ft. Our calculator gives you exact amounts.
What is the difference between sanded and unsanded grout?
Sanded grout is used for joints wider than 1/8 inch — the sand provides strength and prevents cracking. Unsanded grout is for narrow joints 1/8 inch or less, and is smoother. Unsanded is also required for polished marble and soft stone tiles.
How much thinset mortar do I need?
Thinset coverage depends on trowel notch size. A 1/4×1/4 inch notch covers about 75-85 sq ft per 50-lb bag. A 1/2×1/2 inch notch covers about 40-50 sq ft. Large format tiles (over 15 inches) require back-buttering, using 25-50% more.
What size trowel should I use?
For tiles up to 8×8 inches: 1/4×1/4 inch. For 12×12 tiles: 1/4×3/8 inch. For 13-16 inch tiles: 1/2×1/2 inch. For tiles larger than 16 inches: 1/2×1/2 inch with back-buttering. Always check manufacturer recommendations.
How do I calculate tile grout for a backsplash?
Measure the backsplash area (length × height minus outlets and windows). For subway tile (3×6 inches) with 1/16-inch joints on 30 sq ft, you’ll need about 5-6 lbs of unsanded grout. Our calculator provides exact estimates based on your tile and joint sizes.
What grout color should I choose?
For a uniform look, match the grout to the tile color. For contrast and to highlight tile patterns, choose a contrasting color. White grout shows dirt more but brightens spaces. Gray is the most popular — it’s neutral and hides stains well.
How long does grout take to dry?
Grout is ready for light foot traffic in 24-48 hours. Full curing takes 28 days. Avoid heavy traffic for 72 hours. Don’t get grout wet for at least 24 hours after application. Apply sealer after full curing (72 hours minimum).
Do I need to seal grout?
Sanded and unsanded cement-based grout should be sealed to prevent staining and moisture absorption. Seal after full cure (72 hours-28 days). Reapply sealer annually. Epoxy grout does NOT need sealing as it’s naturally waterproof.
What is epoxy grout?
Epoxy grout is a two-part (resin + hardener) grout that’s waterproof, stain-proof, and extremely durable. It doesn’t need sealing. Ideal for kitchens, bathrooms, showers, and pools. It costs 2-3x more and is harder to work with than cement grout.
How wide should grout lines be?
Standard grout joint widths: 1/16 inch for rectified tiles, 1/8 inch for most floor and wall tiles, 3/16 inch for rustic or handmade tiles, 1/4 inch for natural stone. Wider joints accommodate tile size variation and provide visual interest.
How much grout do I need for subway tile?
For standard 3×6 inch subway tiles with 1/16-inch joints: about 1 lb of grout per 10 sq ft. With 1/8-inch joints: about 2 lbs per 10 sq ft. A typical kitchen backsplash (30 sq ft) needs 3-6 lbs depending on joint width.
Can I grout over old grout?
You can apply new grout over old if the existing grout is clean, sound, and the joints are at least 2/3 of the original depth. For best results, remove old grout with a grout removal tool or oscillating tool, then apply fresh grout.
What causes grout to crack?
Common causes: too much water in the mix, not enough grout in the joints, movement in the substrate (no expansion joints), mixing different batches inconsistently, and premature exposure to water or traffic before curing.
How do I remove grout haze?
Light haze: wipe with a damp sponge within 15-30 minutes of grouting. Dried haze: use a commercial grout haze remover or a solution of vinegar and water (1:1). For stubborn haze, use a nylon scrub pad. Never use haze remover on natural stone.
How much does grout cost?
Cement-based sanded grout: $8-$15 per 25-lb bag. Unsanded grout: $10-$18 per 10-lb bag. Epoxy grout: $30-$60 per gallon kit. Premixed grout: $15-$25 per quart. A typical bathroom needs $15-$40 in grout.
What is the best grout for showers?
Epoxy grout is the best choice for showers because it’s waterproof and mold-resistant without needing sealer. If using cement grout, choose sanded grout for joints over 1/8 inch, apply a penetrating sealer, and use a grout with built-in mildew resistance.
How do I fix cracked grout?
Remove damaged grout with a grout saw or oscillating tool to at least 2/3 depth. Clean joints with a brush and water. Apply new grout, matching the original color. Let cure 72 hours before sealing. For persistent cracking, check for substrate movement.
How many tiles do I need per square foot?
4×4 inch tiles: 9 per sq ft. 6×6 inch: 4 per sq ft. 12×12 inch: 1 per sq ft. 12×24 inch: 0.5 per sq ft. 24×24 inch: 0.25 per sq ft. Add 10-15% for cuts and waste.
What is a grout float?
A grout float is a flat, rubber-faced tool used to push grout into tile joints. Hold it at a 45-degree angle to the tiles and sweep diagonally across joints. The rubber face prevents scratching tiles while forcing grout into every gap.
Should I use large or small tiles in a small bathroom?
Large tiles (12×24 or larger) make small bathrooms appear bigger because there are fewer grout lines. However, small mosaic tiles work well on shower floors where you need slope for drainage. Balance aesthetics with practical needs.
How do I calculate tiles for a pattern layout?
For herringbone or chevron patterns, add 15-20% extra for waste. For diagonal layouts, add 15%. For brick-offset patterns, add 10%. Standard straight layouts need only 10% extra. Always do a dry layout first to plan cuts.
What is grout sealer and how do I apply it?
Grout sealer is a liquid that penetrates cement grout to repel water and stains. Apply with a small brush or applicator bottle along grout lines. Wipe excess from tile surfaces. Let dry 2-4 hours. Apply 2 coats for best protection.
Can I change my grout color?
Yes, use a grout colorant or grout stain to change the color of existing grout. Clean grout thoroughly first. Apply colorant with a small brush, wipe excess immediately. Two coats are usually needed. Results last 5-15 years depending on the product.
What is the best grout for kitchen floors?
Sanded cement grout with sealer is the standard choice for kitchen floors. Epoxy grout is the premium option — stain-proof and easy to clean. Choose a medium color (gray or beige) that hides dirt and food stains better than white.
How do I prevent mold in grout?
Seal grout properly and reseal annually. Ensure good bathroom ventilation (run fan 20+ minutes after showers). Wipe wet tile surfaces after use. Use mold-resistant grout. Clean weekly with a mild cleaner. Fix any leaks immediately.
What is the difference between grout and caulk?
Grout fills joints between tiles on flat surfaces. Caulk fills joints where surfaces meet at angles (wall-to-floor, wall-to-wall, around tubs). Use color-matched caulk at transitions and change-of-plane joints. Caulk is flexible; grout is rigid.
How thick should thinset be under tile?
After setting the tile, the thinset layer should be about 3/32 to 1/8 inch thick. This is achieved by using the correct trowel notch size and pressing tiles firmly into the mortar. Too thick risks cracking; too thin risks poor adhesion.
Do I need a membrane under tile?
Waterproof membranes are required in wet areas (showers, tub surrounds). Uncoupling membranes (like Schluter DITRA) are recommended over concrete and plywood substrates to prevent cracking. They add cost but significantly improve durability.
How do I grout mosaic tile?
For mosaic tiles, use unsanded grout for narrow joints. Apply liberally, working in small sections. Use a grout float at various angles to fill all joints. Clean with a damp sponge, rinsing frequently. Mosaic tiles use more grout per square foot than large tiles.
What is premixed grout?
Premixed grout comes ready to use from the container — no mixing required. It’s convenient for small projects and ensures consistent color. It costs more than powdered grout and has a shorter shelf life once opened. Not recommended for large floor areas.