Grout Calculator
Calculate exactly how much grout your tile job needs — from tile size, joint width and depth — in pounds and bags, with sanded vs unsanded guidance.
From the tile calculator, or length × width
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You might also need:Tile Calculator·Flooring Calculator
The grout volume formula
bags = (area × lb per sq ft × 1.15 waste) ÷ bag size
The key insight: grout volume depends on total joint length, which grows as tiles get smaller. 120 sq ft of 12 × 12 inch tile with ⅛-inch joints needs about 13 lb of grout — one 25 lb bag with plenty spare. The same area in 2-inch mosaic needs nearly 70 lb, or three bags.
Grout use by tile size (per 100 sq ft, ⅛″ joints)
| Tile size | Approx. grout | 25 lb bags |
|---|---|---|
| 2 × 2″ mosaic | ~57 lb | 3 |
| 4 × 4″ | ~29 lb | 2 |
| 3 × 6″ subway | ~26 lb | 2 |
| 12 × 12″ | ~11 lb | 1 |
| 12 × 24″ | ~8 lb | 1 |
| 24 × 24″ | ~6 lb | 1 |
Grouting tips
- Buy all bags in one lot: cement grout color varies slightly between production batches, and a color shift halfway across a floor is permanent.
- Mix small batches: grout starts setting in about 30 minutes. Mix what you can spread and clean in that window.
- Clean in two passes: a damp sponge to shape the joints, then a second pass 20 minutes later for haze. Buffing dried haze off is far harder.
- Count your tiles first with the tile calculator; broader floor coverings are in the flooring calculator.
Frequently asked questions
How much grout do I need per square foot?+
It depends on tile size and joint width. Small tiles with wide joints use the most: 4 × 4 inch tile with ¼-inch joints needs about 0.5 lb per square foot, while 12 × 24 inch tile with ⅛-inch joints needs only about 0.1 lb. This calculator works it out from your exact tile and joint size.
Should I use sanded or unsanded grout?+
Sanded grout for joints ⅛ inch and wider — the sand prevents shrinkage cracking. Unsanded for joints under ⅛ inch, and for polished marble or glass tile that sand would scratch. Epoxy grout works at any width and is the choice for showers and heavy-stain areas.
How many square feet does a 25 lb bag of grout cover?+
Roughly 100–200 sq ft for typical 12 × 12 inch floor tile with ⅛–3/16 inch joints. Coverage drops sharply with smaller tiles: the same bag might only do 50 sq ft of mosaic. Manufacturers print coverage charts on the bag — worth checking against your numbers.
How long should I wait before grouting new tile?+
Wait 24–48 hours after setting the tile so the thinset cures — grouting too early traps moisture and can cause haze or weak joints. After grouting, wait another 48–72 hours before sealing, and up to a week before heavy water exposure in a shower.
Do I need to seal grout?+
Cement-based grout should be sealed after it cures, and resealed every 1–2 years in wet areas — unsealed grout absorbs water and stains. Epoxy grout never needs sealing, which is why it costs more and is harder to work with.