Mosaic, hexagon and penny tile: sheets, thinset and grout
By Michał Białas · Last updated
Buy mosaic by the sheet: a nominal 12 × 12 in sheet covers about 0.97 sq ft once laid, so 30 sq ft takes 35 sheets with 10% waste. Budget far more grout than for large tile — penny rounds take about 0.70 lb per sq ft, roughly ten times as much as 12 × 12 tile.
How many mosaic sheets
A mosaic sheet is smaller than its nominal size: a “12 × 12” sheet is usually 11 3/4 in, and the grout joint between sheets adds back a little. The area one sheet covers is (sheet + joint) × (sheet + joint). Divide the floor area plus waste by that, and round up.
| Sheet | Laid coverage | Sheets |
|---|---|---|
| 12 × 12 in nominal (11 3/4 in) | About 0.97 sq ft | About 1.03 per sq ft |
| 300 × 300 mm | About 0.091 m² | About 11 per m² |
| Hexagon sheet 325 × 282 mm | About 0.092 m² | About 10.9 per m² |
Waste with sheets is about 10%: sheets are cut along the joints, so off-cuts are clean and part sheets fill edges. The mosaic tile calculator takes the sheet size or the coverage printed on the box.
Measuring hexagon tile
Hexagons are sold by their size flat to flat (side to side) or point to point (corner to corner), and the two differ by about 15%. Point to point × 0.866 gives flat to flat. Loose hexagons need 15% waste, because every cut at a wall is angled and an off-cut rarely fits elsewhere. Measure one piece yourself before you buy: the name on the box is a nominal size, and the real piece is often a little smaller, with the joint making up the difference.
- Flat to flat: lay a tape across the tile from one straight side to the opposite straight side.
- Point to point: measure from one corner to the opposite corner — the longest distance across.
- Hexagon sheets are counted like square sheets, by the coverage of one sheet.
- Loose hexagons are counted by the piece, using the area of one hexagon plus its joint.
Grout for small tile
Grout fills the joints, so the more joint length per square foot, the more grout. A 1 in hexagon has twice the joint length of a 1 in square; penny rounds leave open triangles between the circles that take far more grout than any straight joint. The depth is the tile thickness. That is why a bag that grouts a whole kitchen of large porcelain may not finish a small bathroom floor of penny rounds, and why running out halfway through a mosaic is so common: the second bag is often from a different batch and dries to a slightly different shade.
| Tile | Grout |
|---|---|
| 12 × 12 × 3/8 in, 1/8 in joints | 0.065 lb per sq ft |
| 1 in hexagon, 1/16 in joint, 1/4 in deep | 0.26 lb per sq ft |
| 3/4 in penny round, 1/8 in spacing, 1/4 in deep | 0.70 lb per sq ft |
| Same pennies in a square grid | 0.88 lb per sq ft |
Example 1 (feet): 30 sq ft of 3/4 in penny round on 11 3/4 in sheets
- Sheets: 1/16 in joint → 0.969 sq ft laid; 30 × 1.10 ÷ 0.969 → 35 sheets, 4 boxes of 10.
- Penny grout, hex packing: open share f = 0.334; G = 0.70 lb per sq ft.
- Grout: 30 × 0.70 × 1.15 = 24.0 lb → one 25 lb bag.
- 1 in hexagons on the same floor: 0.26 lb per sq ft, 9.0 lb → one 10 lb bag.
Example 2 (meters): 3 m² of 19 mm penny round
- Spacing 3 mm, 6 mm deep, hex packing: f = 0.324, G = 3.1 kg/m².
- Grout: 3 × 3.1 × 1.15 = 10.7 kg.
- Sheets 300 × 300 mm with 2 mm joints → 37 sheets.
Thinset and trowel for mosaics
- Pieces under 4 in: a 3/16 in V-notch trowel, about 0.3 lb of thinset per sq ft.
- Use a white thinset under glass or light-colored mosaics, which show the bed through the tile.
- Flatten the ridges with the flat of the trowel if thinset squeezes up into the joints.
- Beat each sheet in with a grout float so every piece is bedded.
Clean thinset out of the joints before it sets — a toothpick or a margin trowel works. Thinset left in the joints shows through light grout.
Common mistakes
| Mistake | Result |
|---|---|
| Counting sheets as exactly 1 sq ft | About 3% short, plus no waste |
| Grout estimated as for large tile | Several bags short on a penny round floor |
| Mixing up flat-to-flat and point-to-point | Hexagon count about 15% off |
| A large-tile notch under mosaics | Thinset squeezing up through every joint |
Small joints often call for unsanded or epoxy grout — see sanded, unsanded or epoxy grout.
Frequently asked questions
How many mosaic sheets per square foot?
About 1.03 for a nominal 12 × 12 in sheet, which is 11 3/4 in and covers about 0.97 sq ft laid. In metric, a 300 × 300 mm sheet works out at about 11 per m².
How much grout for penny tile?
About 0.70 lb per sq ft for 3/4 in pennies with 1/8 in spacing, 1/4 in deep — about ten times as much as 12 × 12 tile.
How do you measure hexagon tile?
Usually flat to flat, from one straight side to the opposite one. Point to point is about 15% more; multiply by 0.866 to convert.
Does this work for large hexagon tile?
Yes. Loose hexagons of 8 or 10 in are counted by piece with 15% waste, and their grout is far less than for small mosaics.