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SPECTRALOCK PRO Premium Grout Calculator: How Many Units Do I Need?
Enter your area, tile size and joint width to see how much SPECTRALOCK PRO Premium epoxy grout to buy and which mix of Mini (0.2 gal), Full (0.8 gal) and Commercial (3.2 gal) units covers it. The numbers come from LATICRETE's coverage chart T-10832-FD-1125, which is printed per Mini unit, and data sheet DS-681-1026. For 12 x 12 in tile with 1/8 in joints, the chart gives 40.7 sq ft per Mini unit; the calculator gives about 39.4, slightly on the safe side.
LATICRETE SPECTRALOCK PRO Premium Grout coverage
| Tile | 1/16 in | 1/8 in | 3/16 in | 1/4 in | 5/16 in | 3/8 in | 7/16 in | 1/2 in |
|---|---|---|---|---|---|---|---|---|
| 1 x 1 x 1/4 in | 10.4 | 5.4 | 3.7 | 2.9 | 2.4 | 2.1 | 1.8 | 1.7 |
| 2 x 2 x 1/4 in | 20.5 | 10.4 | 7.1 | 5.4 | 4.4 | 3.7 | 3.2 | 2.9 |
| 4.3 x 4.3 x 0.333 in | 34.6 | 17.4 | 11.7 | 8.8 | 7.1 | 6 | 5.2 | 4.6 |
| 4 x 8 x 1/2 in | 27.1 | 13.6 | 9.1 | 6.9 | 5.5 | 4.6 | 4 | 3.5 |
| 6 x 6 x 1/2 in | 30.5 | 15.3 | 10.2 | 7.7 | 6.2 | 5.2 | 4.5 | 4 |
| 3 x 12 x 3/8 in | 32.5 | 16.3 | 10.9 | 8.2 | 6.6 | 5.5 | 4.8 | 4.2 |
| 12 x 12 x 3/8 in | 81.1 | 40.7 | 27.1 | 20.4 | 16.4 | 13.7 | 11.8 | 10.3 |
| 18 x 18 x 3/8 in | 121.5 | 60.9 | 40.5 | 30.5 | 24.4 | 20.4 | 17.5 | 15.4 |
| 18 x 18 x 1/2 in | 91.2 | 45.7 | 30.4 | 22.9 | 18.3 | 15.3 | 13.1 | 11.5 |
| 24 x 6 x 3/8 in | 64.8 | 32.5 | 21.6 | 16.3 | 13.1 | 10.9 | 9.4 | 8.2 |
| 24 x 12 x 3/8 in | 108 | 54.1 | 36 | 27.2 | 21.7 | 18.2 | 15.6 | 13.7 |
Source: LATICRETE SPECTRALOCK PRO Premium Grout coverage chart T-10832-FD-1125 (approximate coverage per Mini unit), chart © 2025, with data sheet DS-681-1026, read 2026-10-17.
How the calculation works
grout per sq ft = 144 × ((L + W) × J + J²) × T ÷ ((L + J) × (W + J))
units = area × (1 + waste ÷ 100) × grout per sq ft ÷ joint volume one unit fills, rounded up
L and W are the tile length and width, T the tile thickness (the joint is assumed to be filled to full tile depth) and J the joint width, all in inches; the result is in cubic inches. The volume one unit fills is worked back from the manufacturer's coverage chart and set at the lowest value any cell of the chart implies, so for every tile size in the chart this calculator gives the same or less coverage than the data sheet, never more. Tiles not in the chart use the same formula.
Worked example
A 200 sq ft floor of 12 x 12 x 3/8 in tile with 1/8 in joints and 10% extra: 220 sq ft to grout. Each tile plus its share of joint is a 12.125 × 12.125 in square, and the joint part of it holds (12 + 12) × 1/8 + 1/8² = 3.016 sq in, 3/8 in deep. That works out to 1.11 cubic inches of grout per sq ft of floor. One 0.2 gal (0.7 L) Mini unit fills about 43.6 cubic inches of joint at this tile size, so it covers 43.6 ÷ 1.11 = 39.4 sq ft. 220 ÷ 39.4 = 5.59 units of 0.2 gal (0.7 L) Mini unit, or 5.59 × 0.2 gal = 1.12 gallons of mixed grout. In the sizes on sale, buy 1 × 0.8 gal Full unit + 2 × 0.2 gal Mini units (1.2 gal).
LATICRETE SPECTRALOCK PRO Premium Grout key specs
| Product type | Tile grout |
|---|---|
| Package | 0.2 gal (0.7 L) Mini unit |
| Joint width range | 1/16–1/2 in |
| Coverage (chart, per Mini unit) | 12 x 12 x 3/8" tile 81.1 sq ft at 1/16", 40.7 at 1/8", 20.4 at 1/4", 10.3 at 1/2"; 1 x 1 x 1/4" mosaic 10.4 at 1/16", 5.4 at 1/8" (full chart above) |
| Unit sizes | Mini 0.2 US gal (0.7 L): Part A 4.6 fl oz, Part B 4.6 fl oz, Part C powder 2 lb (0.9 kg); Full 0.8 US gal (3.0 L): A 18.1 fl oz, B 18.6 fl oz, C 9.0 lb (4.0 kg); Commercial 3.2 US gal (12.0 L): 4 x the Full unit parts |
| Waste allowance | LATICRETE says add 10% for waste, spillage and clean-up, and another 10–15% for unglazed quarry tile |
| Joint width | 1/16" to 1/2" (1.5–13 mm); it is a sanded grout, so joints under 1/8" (3 mm) get a coarser surface |
| Mixing | do not add water or any other material, and do not re-temper with water |
| Working time | 120 min at 40°F (4°C), 80 min at 70°F (21°C), 30 min at 95°F (35°C) |
| Foot traffic | light: 24 h at 40°F, 12 h at 70°F, 6 h at 95°F; heavy: 48 h, 24 h, 12 h |
| Stain resistance and cure | resists dirt, food spills and household cleaners after 14 / 7 / 3 days (40 / 70 / 95°F); full cure 28 / 14 / 7 days |
| Pools and steam rooms | cure 10 days at 70°F (21°C) before use or filling with water |
| Sealing | never needs sealing (data sheet) |
| Standards | meets ANSI A118.3; UL GREENGUARD certified for low chemical emissions; VOC 0.00026 lb/gal (0.031 g/L) |
| Density | about 15 lb per US gallon (1.8 g/mL) mixed |
| Not for | areas with harsh chemicals or steam cleaning, commercial kitchen floors and bases, veterinary clinic and kennel floors (LATICRETE points to SPECTRALOCK 2000 IG, ANSI A118.5, for those); not a waterproofing membrane |
What SPECTRALOCK PRO Premium is
SPECTRALOCK PRO Premium Grout is LATICRETE's mainstream epoxy grout. Instead of a cement powder mixed with water, it comes as three parts: two liquids (Part A and Part B) and a colored sand powder (Part C). Mixed together they cure by chemical reaction into a hard, dense joint that the data sheet calls stainproof to common household cleaners and liquids in residential work, and that never needs sealing. It meets ANSI A118.3, the standard for chemical-resistant epoxy grouts, and it is rated for joints from 1/16 to 1/2 inch on floors and walls, inside and outside, including showers, swimming pools and fountains.
Because it is a sanded grout, LATICRETE warns that joints narrower than 1/8 inch will have a coarser surface than wider joints. Some soft polished marble and delicate glazed or glass tile can be scratched during installation, and epoxy resins can change the color of white or porous stone such as White Carrara or Thassos, so test a small area first on those materials.
Mini, Full and Commercial units
Epoxy grout is not sold by weight like cement grout. LATICRETE sells three unit sizes, and data sheet DS-681-1026 gives each as a yield of mixed grout: the Mini unit makes 0.2 US gallon (0.7 L), the Full unit 0.8 gallon (3.0 L) and the Commercial unit 3.2 gallons (12.0 L). A Full unit is four Minis and a Commercial unit is four Full units packed together. The coverage chart is printed per Mini unit, so for a Full unit multiply the chart by four and for a Commercial unit by sixteen.
The calculator works out the total gallons first and then chooses a mix of units. It uses the fewest units that cover the job without leaving more than one Mini unit's worth of grout unused. Do not try to mix part of a unit: the three parts are proportioned to be mixed whole, and the data sheet says not to add water or anything else to the mix.
How the calculator works
Grout only fills the gaps between tiles, so the amount depends on how much joint there is in each square foot. The calculator treats one tile plus half a joint on each side as a rectangle (L + J) by (W + J). The joint part of that rectangle is (L + W) × J + J² square inches, filled to the full tile thickness T. Dividing by the rectangle's area and multiplying by 144 gives cubic inches of grout per square foot of floor.
LATICRETE does not say how many cubic inches of joint a Mini unit fills, so that number was worked back from all 88 cells of the coverage chart. Here the chart has a pattern that a single number cannot follow. On 12 inch and larger tile, the cells imply about 43.6 to 45.4 cubic inches per Mini unit, close to the 46.2 cubic inches in 0.2 gallon. On 1 x 1 inch mosaic they imply as little as 33.4, on 2 x 2 inch about 37.6, and on 3 x 12 inch about 40.2. That matches what installers see: small tiles and narrow strips waste more grout on the tile face, in the float and in cleanup.
If the calculator used the mosaic figure for everything, it would tell you to buy about a quarter more grout than you need for large-format floors. If it used the large-tile figure, it would leave you short on mosaics. So it picks the volume by the shorter side of your tile, in six steps: 1 inch and up 33.4 cubic inches, 2 inch 37.5, 3 inch 40.1, 4 inch 41.1, 6 inch 42.4, 12 inch 43.6 and 18 inch 44.1. Each step is the lowest value any chart row at or above that size implies, rounded down, and a tile between steps uses the lower step. At the build stage every chart cell is checked, and the site will not publish if the calculator ever gives more than the chart.
Entering your tile and joint
Measure the tile itself, not the nominal size on the box, and use the real thickness, since a 1/2 inch thick tile needs a third more grout than a 3/8 inch one with the same joint. Joint width matters even more: going from 1/8 to 1/4 inch roughly halves the coverage. For a mix of tile sizes, run each area separately. LATICRETE's own advice is to add 10 percent for waste, spillage and clean-up, which is the calculator's default, and another 10 to 15 percent for unglazed quarry tile, where the rough face holds more grout.
Working time and cure
Temperature changes everything with epoxy. The data sheet gives 120 minutes of working time at 40°F (4°C), 80 minutes at 70°F (21°C) and only 30 minutes at 95°F (35°C). Light foot traffic is allowed after 24, 12 or 6 hours at those temperatures, and heavy traffic after 48, 24 or 12 hours. Full stain resistance against food spills and household cleaners takes 14, 7 or 3 days, and full cure 28, 14 or 7 days. Pools and steam rooms need 10 days at 70°F before use. On a warm day, mixing one Mini or Full unit at a time is safer than opening a Commercial unit you cannot finish.
Check before you buy
The chart and this calculator are estimates; LATICRETE notes that actual coverage depends on site conditions, real tile size and installed joint width. Read the current data sheet and the instructions in the unit before mixing, and keep the grout away from propane heaters, which can make epoxy yellow. For areas with harsh chemicals, steam cleaning or commercial kitchen floors, LATICRETE recommends its SPECTRALOCK 2000 IG industrial grout instead.
FAQ
How much does a SPECTRALOCK PRO Premium Mini unit cover?
It depends on tile size and joint width. LATICRETE's chart gives 40.7 sq ft per Mini unit (0.2 gallon) for 12 x 12 x 3/8 inch tile with 1/8 inch joints, 81.1 sq ft at 1/16 inch and 20.4 sq ft at 1/4 inch. Mosaics use far more: 1 x 1 inch mosaic with 1/8 inch joints covers only 5.4 sq ft per Mini unit. A Full unit is four times a Mini and a Commercial unit is sixteen times a Mini, so multiply the chart by 4 or 16.
Should I buy Mini, Full or Commercial units?
The calculator converts the job to gallons and picks the fewest units that cover it without leaving more than one Mini unit's worth unused, so a job needing 0.75 gallon gets one Full unit rather than four Minis. Working time also matters: the data sheet gives 80 minutes at 70°F but only 30 minutes at 95°F, so on a hot job several smaller units mixed one at a time can be easier to finish than one large batch.
Why does the calculator use a different grout volume for mosaics?
LATICRETE's chart is not simply proportional to joint volume. Worked back from the chart, a Mini unit fills about 43.6 to 45 cubic inches of joint on 12 inch and larger tile, but only about 33.4 cubic inches on 1 x 1 inch mosaic. The calculator uses the lowest value the chart implies for your tile's shorter side, so it never shows more coverage than the chart for any tile size and joint in it.
Do I need to seal SPECTRALOCK PRO Premium grout?
No. Data sheet DS-681-1026 says it never needs sealing and is stainproof to common household cleaners and liquids in residential installations, provided spills are cleaned up promptly. Full stain protection takes about seven days at 70°F (21°C); during that time keep acids such as mustard or salad dressing, strong cleaners and construction dirt off the grout.
How soon can I use a shower or pool grouted with it?
At 70°F (21°C) the data sheet allows light foot traffic after 12 hours and heavy traffic after 24 hours, with full cure in 14 days. For steam rooms and submerged installations such as pools and fountains, LATICRETE asks for 10 days of cure at 70°F before using the area or filling it with water. Colder conditions slow every step: at 40°F (4°C) full cure takes 28 days.
LATICRETE and LATICRETE SPECTRALOCK PRO Premium Grout are trademarks of their owner. This page is an independent estimate based on the published data sheet; check the bag label before mixing.