Should I use sanded or unsanded grout?

Use unsanded grout for narrow joints up to 1/8 inch and for polished or easily scratched tile like glass and polished stone. Use sanded grout for joints 1/8 inch and wider — the sand resists shrinking and cracking in bigger joints, and it is standard for floors. Epoxy grout is a third option for stain-proof, waterproof joints in wet or heavy-use areas.

How much does a bag of grout cover?

It depends entirely on tile and joint size. A 25 lb bag might cover 200 or more square feet of large tile with thin joints, around 100 sq ft with 1/4-inch joints, or as little as 50 to 60 sq ft of small mosaic. The calculator works out the pounds you need and the coverage for your exact setup.

Do I need to seal grout?

Cement-based grout, both sanded and unsanded, is porous and should be sealed once it cures — usually 48 to 72 hours — to resist stains and moisture, then resealed periodically. Epoxy grout does not need sealing because it is already stain- and water-resistant.

Grout Calculator — How Much Grout Do I Need?

Q: How much grout do I need?

Grout fills the joints between tiles, so the amount depends on your tile size, tile thickness, and joint width — not just the floor area. Smaller tiles and wider, deeper joints need much more. As a guide, a 25 lb bag of sanded grout covers roughly 200 sq ft of 12-inch floor tile with 1/8-inch joints, but only about 55 sq ft of 2-inch mosaic. Enter your tile and joint sizes for an exact figure.

How much grout do I need?

Grout doesn't cover an area the way paint or thinset does — it fills the joints between tiles. So the amount you need depends on how much joint there is, which comes down to four things: tile length, tile width, tile thickness, and joint width. The standard estimate is:

Pounds per sq ft = ((tile L + tile W) ÷ (tile L × tile W)) × joint width × tile thickness × 14.5

(All tile dimensions in inches.) Multiply by your tiled area, then divide by the bag size and round up. The takeaways: smaller tiles have more joint per square foot — a mosaic uses several times the grout of a big tile — and wider or deeper joints use proportionally more. That's why this calculator asks for tile and joint sizes instead of just area.

What drives grout coverage

Here's how far a single 25 lb bag of sanded grout stretches for some common setups. Notice how much tile size and joint width change the answer.

Tile & joint	Grout per 100 sq ft	25 lb bag covers
2×2″ mosaic, 1/8″ joint	~45 lbs	~55 sq ft
3×6″ subway, 1/16″ joint	~14 lbs	~175 sq ft
12×12″ floor, 1/8″ joint	~11 lbs	~220 sq ft
12×12″ floor, 1/4″ joint	~23 lbs	~110 sq ft
18×18″ floor, 3/16″ joint	~11 lbs	~220 sq ft

Assumes 3/8″ tile thickness (5/16″ for subway, 1/4″ for mosaic). Your bag may differ — match the price and bag size to what you buy.

Sanded vs. unsanded vs. epoxy

Unsanded grout — for narrow joints up to 1/8″ and for polished or scratch-prone tile like glass, metal, and polished stone.
Sanded grout — for joints 1/8″ and wider. The sand resists shrinking and cracking, and it's the standard for floors.
Epoxy grout — stain-proof and waterproof, ideal for kitchens, showers, and heavy use. It's pricier, sets fast, and is estimated by its own kit coverage.

Tips for grouting tile

Let the thinset cure first. Wait at least 24 hours after setting tile before you grout, so the mortar isn't still wet under the tile.
Mix small batches. Grout starts setting in the bucket — mix what you can spread and clean in about 30 minutes, and don't add water to revive it.
Pack joints full. Work the float diagonally across the tile to force grout in with no gaps or low spots, then tool the joints consistently.
Seal cement grout. After it cures (48–72 hours), seal sanded and unsanded grout to fight stains, and reseal every year or two in wet areas.

Choosing a grout color

Grout color changes the whole look of a tiled surface. Matching the grout to the tile makes the surface read as one seamless field and hides the grid; a contrasting color frames each tile and shows off a pattern like subway or herringbone. Practical notes: a mid-tone hides dirt better than bright white (which grays over time) or very dark (which can show efflorescence), so it's the easy-care choice for floors. Always check the color on a dry sample — wet grout looks darker than it dries — and mix consistently from the same lot so the color doesn't shift across the room.

Frequently asked questions

How much grout for 100 sq ft?

For 12-inch floor tile with 1/8-inch joints, about 11 lbs — roughly half a 25 lb bag, so one bag. Smaller tile or wider joints can easily push that to two or more.

Sanded or unsanded?

Unsanded for joints up to 1/8 inch and scratch-prone tile; sanded for 1/8 inch and wider, including most floors. The calculator's math is the same either way.

How much does a bag cover?

Anywhere from ~50 sq ft (small mosaic) to 200+ sq ft (big tile, thin joints). Coverage is set by tile and joint size, which is why this calculator asks for them.

Should I seal grout?

Yes — seal cement grout after it cures (48–72 hours) and reseal periodically. Epoxy grout doesn't need sealing.

What color grout should I choose?

Match the tile for a seamless look, or contrast it to frame each tile. A mid-tone hides dirt best — easier care than bright white or very dark. Check a dry sample, since grout dries lighter than it looks wet.

Can I change grout color later?

Yes — a grout colorant/stain can recolor cured cement grout (and reseals it), or you can rake out the top layer and re-grout. Epoxy grout can't be stained over.

How long before I can walk on grouted tile?

Usually about 24 hours for light foot traffic, and 48–72 hours before sealing or heavy use. Cool, humid conditions slow it down — follow the bag.

Grout Calculator