Most tiles are 1/4" to 3/8" thick
Include walls and floors separately if different tiles
10% is standard, 15% for irregular tile
Grout Needed (25-lb bags)
2 bags
25.1 lbs of sanded grout
Material Quantities
Bag Options
25-lb bags are the most cost-effective. 10-lb bags work for small repairs or when you need an exact color match without leftovers.
Cost Estimate (25-lb bags)
12,800+ estimates calculated this month
Last updated: 2026-03-13
How to Calculate Grout for Any Tile Job
Grout quantity depends on four things: tile size, joint width, tile thickness, and total area. Smaller tiles with wider joints eat through grout fast. A 1x1 mosaic with 1/16" joints uses nearly 8x more grout per square foot than a 24x24 tile with the same joint width. The formula is straightforward once you know your numbers, and the calculator above handles all of it.
I've seen guys show up to a tile job with one bag of grout for 200 square feet of subway tile and think they're set. Sometimes they are. But if you're working with 4x4 tile or mosaics, one bag might not even cover 50 square feet. Run the numbers first and save yourself the extra trip to the supply house mid-job.
Inputs you'll need
- Tile dimensions - Length and width in inches (e.g. 12x12, 3x6, 1x1)
- Tile thickness - Usually 1/4" for wall tile, 3/8" for floor tile
- Grout joint width - The gap between tiles (1/16" to 1/2")
- Total area - Square footage of the tiled surface
- Grout type - Sanded, unsanded, or epoxy
Grout Coverage by Tile Size (25-lb bag, 1/8" joints)
| Tile Size | Lbs per Sq Ft | 25-lb Bag Covers | Best Grout Type |
|---|---|---|---|
| 1" x 1" mosaic | 1.82 lbs | ~14 sq ft | Unsanded |
| 2" x 2" mosaic | 0.91 lbs | ~27 sq ft | Unsanded |
| 4" x 4" | 0.46 lbs | ~55 sq ft | Sanded |
| 6" x 6" | 0.30 lbs | ~83 sq ft | Sanded |
| 12" x 12" | 0.23 lbs | ~110 sq ft | Sanded |
| 12" x 24" | 0.17 lbs | ~147 sq ft | Sanded |
| 24" x 24" | 0.11 lbs | ~220 sq ft | Sanded |
Table assumes 3/8" tile thickness and 1/8" grout joints. Adjust in the calculator above for your exact specs. Our tile calculator can help figure your tile quantity before you move on to grout.
Worked examples
Example A: 100 sq ft bathroom floor, 12x12 tile, 1/8" sanded joints
- Grout per sq ft: 0.23 lbs (12x12 at 3/8" thick, 1/8" joints)
- Base: 100 x 0.23 = 23 lbs
- With 10% waste: 25.3 lbs
- You need: 2 bags of 25-lb sanded grout ($24-$50)
Example B: 30 sq ft kitchen backsplash, 3x6 subway tile, 1/16" unsanded joints
- Grout per sq ft: 0.23 lbs (3x6 at 1/4" thick, 1/16" joints)
- Base: 30 x 0.23 = 6.9 lbs
- With 10% waste: 7.6 lbs
- You need: 1 bag of 10-lb unsanded grout ($14-$30)
Example C: 500 sq ft commercial floor, 12x24 tile, 1/8" sanded joints
- Grout per sq ft: 0.17 lbs (12x24 at 3/8" thick, 1/8" joints)
- Base: 500 x 0.17 = 85 lbs
- With 10% waste: 93.5 lbs
- You need: 4 bags of 25-lb sanded grout ($48-$100)
Sanded vs. Unsanded vs. Epoxy: Which Grout to Use
| Feature | Sanded | Unsanded | Epoxy |
|---|---|---|---|
| Joint Width | 1/8" and wider | Under 1/8" | Any width |
| Cost (25-lb) | $12-$25 | $14-$30 | $35-$80 |
| Needs Sealing | Yes (1-5 yrs) | Yes (1-5 yrs) | No |
| Stain Resistance | Low-Medium | Low-Medium | Excellent |
| Best For | Floors, wide joints | Walls, polished tile | Showers, counters |
| Working Time | 30-45 min | 30-45 min | 15-20 min |
Mistakes I see on grout day
- Mixing the whole bag at once. Grout has a working time of 20-45 minutes depending on type. Mix in small batches - about 2-3 lbs at a time for wall tile, 5-8 lbs for floors. Once it starts to stiffen in the bucket, it's done. You can't save it by adding water.
- Using sanded grout on polished marble. Sand particles will scratch polished stone and glass tile permanently. This is a mistake you can't undo. Always use unsanded or epoxy on polished surfaces, regardless of joint width.
- Skipping the sealer. Unsealed cement grout absorbs everything - coffee, red wine, cooking grease. Within six months the grout lines are stained and dingy. Seal it 48-72 hours after installation and put a reminder on your calendar to reseal annually in wet areas.
- Grouting before the thinset cures. Wait at least 24 hours after setting tile before grouting. If the thinset is not fully cured, moisture gets trapped between the tile and substrate, which can cause mold and adhesion failure down the road.
- Not buying enough. Running out mid-wall is worse than having an extra bag sitting on the shelf. Grout colors can vary between production batches, so buying from the same lot matters. Buy an extra bag and return it if you don't need it.
Field tips for cleaner grout lines
- Work in small sections. Grout a 3x3 foot area, clean it, then move on. Letting grout haze dry on the tile face means twice the cleanup work.
- Use a grout float at 45 degrees. Push grout diagonally across the joints, not parallel to them. Parallel strokes pull grout out of the joints instead of packing it in.
- Wring out your sponge. When cleaning grout haze, the sponge should be barely damp - not dripping. Too much water washes pigment out of the joints and leaves light, chalky grout lines.
- Final wipe with cheesecloth. After the initial sponge cleanup, wait 15-20 minutes and buff the tile surface with dry cheesecloth or a microfiber towel. This removes the last of the haze without disturbing the joints.
Building a full tile estimate? Our tile calculator handles quantity and layout, the thinset calculator figures your mortar needs, and EstimationPro puts the whole project together into a professional estimate your client can sign off on. EstimationPro doesn't just build the estimate - it sends the proposal and follows up with the homeowner so you win more of the bids you already send. Try EstimationPro free.
How to Use This Calculator
Select your tile size
Pick from common presets like 12x12, 3x6 subway, or 12x24 large format. Or enter custom dimensions for any tile size including mosaics.
Set the grout joint width
Choose the gap between tiles - 1/16" for tight rectified joints, 1/8" for standard spacing, up to 1/2" for flagstone or saltillo tile.
Choose your grout type
Select sanded grout for joints 1/8" and wider, unsanded for narrower joints, or epoxy for wet areas and high-traffic commercial floors.
Enter total tile area
Input the square footage of your tile installation. The calculator gives you total pounds, bag counts (10-lb and 25-lb), and cost estimates with a waste factor built in.
Grout Calculation Formula
Grout (lbs/sq ft) = (Joint Width x Tile Thickness x (Tile Length + Tile Width)) / (Tile Length x Tile Width) x 144 / 1728 x Density
Total Grout (lbs) = Grout per Sq Ft x Area x (1 + Waste%)
Bags (25-lb) = ceil(Total Grout / 25)Where:
- Joint Width
- = Grout joint width in inches (e.g. 0.125 for 1/8")
- Tile Thickness
- = Tile depth in inches (typically 0.25" to 0.375")
- Tile Length, Width
- = Tile face dimensions in inches
- 144
- = Square inches per square foot (12 x 12)
- 1728
- = Cubic inches per cubic foot (12 x 12 x 12)
- Density
- = ~100 lbs/cu ft for cement grout, ~115 for epoxy
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Frequently Asked Questions
How much grout do I need per square foot of tile?
It depends on tile size and joint width. For 12x12 tiles with 1/8" joints, you need about 0.23 lbs per square foot. For 6x6 tile with 1/8" joints, that jumps to about 0.30 lbs per sq ft. Smaller tiles and wider joints mean more grout. A 25-lb bag of sanded grout covers roughly 55-220 sq ft depending on tile size and joint width.
Should I use sanded or unsanded grout?
The rule is simple: sanded grout for joints 1/8" and wider, unsanded for joints under 1/8". Sand particles give sanded grout the aggregate it needs to fill wider joints without shrinking and cracking. In narrow joints, those same sand particles can scratch polished marble, glass tile, or metal tile. For shower floors and wet areas, consider epoxy grout regardless of joint size - it never needs sealing.
How much does grout cost in 2026?
Sanded grout runs $12-$25 per 25-lb bag. Unsanded grout costs $14-$30 per 25-lb bag. Epoxy grout is the premium option at $35-$80 per unit, but it is waterproof, stain-proof, and never needs resealing. For a typical 100 sq ft bathroom floor with 12x12 tile, grout material costs run $12-$50 total. Grout is one of the cheapest materials in a tile job.
How many square feet does a 25-lb bag of grout cover?
Coverage varies widely by tile size and joint width. A 25-lb bag of sanded grout covers approximately:
- 80-85 sq ft of 6x6 tile with 1/8" joints
- 105-115 sq ft of 12x12 tile with 1/8" joints
- 140-150 sq ft of 12x24 tile with 1/8" joints
Wall tiles (1/4" thick) use less grout per square foot than floor tiles (3/8" thick).
How much grout do I need for subway tile?
Standard 3x6 subway tile with 1/16" joints uses about 0.23 lbs of grout per square foot. A typical subway tile backsplash of 30 sq ft needs roughly 7-8 lbs of grout (one 10-lb bag with some left over). For a full shower surround at 80-100 sq ft, plan on 20-25 lbs (one 25-lb bag). Use unsanded grout for subway tile since the joints are typically 1/16".
What waste factor should I use for grout?
Use 10% waste for standard rectangular tile on flat surfaces. Bump to 15% for irregular or handmade tile (like zellige or terracotta), curved surfaces, or if you are a first-time tiler. For mosaics with lots of small joints, 10% is fine because the mixing and application process is more controlled. Always mix grout in small batches - once it starts to set, you cannot add water to thin it back out.
When should I use epoxy grout instead of cement grout?
Use epoxy grout in these situations: shower floors and steam showers (constant water exposure), kitchen countertops (stain resistance), commercial kitchens and restaurants (health code requirements), and pool tile (chemical resistance). Epoxy costs 2-3x more than cement grout but never needs sealing, does not absorb stains, and will not crack or crumble over time. The tradeoff is that it is harder to work with and sets faster.
Do I need to seal grout?
Cement-based grout (sanded and unsanded) should always be sealed after it fully cures (usually 48-72 hours). Grout sealer costs $8-$15 per bottle and covers 50-200 sq ft. Reseal every 1-2 years in wet areas, every 3-5 years on floors. Epoxy grout does not need sealing at all, which is one of its biggest advantages despite the higher upfront cost.
How do I calculate grout for mosaic tile?
Mosaic tiles use more grout per square foot because of the many small joints. For 1x1 mosaic with 1/16" joints, figure about 0.91 lbs per sq ft. For 2x2 mosaic, roughly 0.46 lbs per sq ft. A 25-lb bag covers about 27 sq ft of 1x1 mosaic versus 110 sq ft of 12x12 tile. Enter your mosaic dimensions in the calculator above for exact quantities.
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