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SPECTRALOCK 1 Grout Calculator: How Many Gallon Pails?

Enter your area, tile size and joint width to see how many 1 gallon (3.8 L) pails of SPECTRALOCK 1 to buy. The calculator follows the coverage table in LATICRETE's North American data sheet DS-36589-1026, which covers joints from 1/16 to 3/8 inch, and is set so it never claims more coverage than that table. For 12 x 24 in tile with 1/8 in joints, LATICRETE gives 275 sq ft per gallon; the calculator gives about 274.

LATICRETE SPECTRALOCK 1 Pre-Mixed Grout coverage

Source: LATICRETE Data Sheet: SPECTRALOCK 1 Pre-Mixed Grout (North America, English), DS-36589-1026, read 2026-10-17.

How the calculation works

grout per sq ft = 144 × (L + W) × J × T ÷ (L × W)
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. This is the textbook grout formula, and it is the one this manufacturer's chart follows: worked back from every cell, the chart implies almost the same joint volume per pail. The calculator uses the lowest value any cell implies, so for every tile size in the chart it gives the same or less coverage than the data sheet, never more. Tiles not in the chart use the same formula.

Worked example

A 400 sq ft floor of 12 x 24 x 3/8 in tile with 1/8 in joints and 10% extra: 440 sq ft to grout. Each 12 × 24 in tile (288 sq in) carries (12 + 24) × 1/8 = 4.5 sq in of joint, 3/8 in deep. That works out to 0.84 cubic inches of grout per sq ft of floor. One 1 gal (3.8 L) pail fills about 231 cubic inches of joint, so it covers 231 ÷ 0.84 = 274 sq ft. 440 ÷ 274 = 1.61, so buy 2 pails.

LATICRETE SPECTRALOCK 1 Pre-Mixed Grout key specs

What SPECTRALOCK 1 is

SPECTRALOCK 1 Pre-Mixed Grout from LATICRETE is a ready-to-use grout sold in 1 gallon (3.8 L) pails weighing 14.2 lb (6.4 kg). There is nothing to mix and no water to add: you open the pail, spread it with a rubber float and wash it off. LATICRETE describes it as a patented pre-mixed grout with epoxy performance but without epoxy resins. It exceeds ANSI A118.19, the American standard for ready-to-use grouts, and meets the ANSI A118.3 epoxy grout criterion for compressive strength, with 3,250 to 3,600 psi at 14 days. LATICRETE says the finished grout is equivalent to its SPECTRALOCK PRO Premium two-part epoxy.

The data sheet lists ceramic, glass tile and stone, interior and exterior, floors and walls, residential and commercial work, re-grouting, and swimming pools and fountains. It is marketed as stain proof in residential use, uniform in color, non-sag on walls, never needing sealing, and equipped with antimicrobial protection. The rated joint range is narrower than many grouts: 1/16 to 3/8 inch (2 to 9 mm).

How much one pail covers

The data sheet DS-36589-1026 prints an approximate coverage table per gallon for nine tile sizes and four joint widths. A few examples show how wide the spread is. With 24 x 24 x 3/8 inch porcelain and 1/16 inch joints, one pail covers 822 sq ft. With 12 x 24 inch tile and 1/8 inch joints it covers 275 sq ft. A 2 x 2 inch mosaic at 1/8 inch needs a pail for every 53 sq ft, and a 1 x 1 inch mosaic at 3/8 inch joints covers only 11 sq ft per pail. The same floor area can therefore need anything from one pail to a dozen depending on the tile you picked.

LATICRETE also publishes the table as a separate chart image (T-10831-FD-1025). The two match for 1 x 1, 2 x 2, 4 1/4 x 4 1/4 and 24 x 24 inch tile, but the image is 2 to 3 sq ft higher per cell for the 3 x 6, 4 x 24, 6 x 24, 12 x 24 and 12 x 36 inch rows. This page uses the data sheet figures, which are the lower of the two, so the estimate errs toward buying enough.

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 of floor. The calculator works out the joint volume per square foot from the tile length and width, the joint width and the tile thickness, which sets the joint depth. It then divides the volume one pail fills by that number to get square feet per pail, adds your waste allowance, and rounds the pail count up.

For this product the joint volume uses the standard formula 144 x (L + W) x J x T divided by L x W, in cubic inches per square foot. Worked backward from every cell in LATICRETE's table, that formula implies about 231 to 233 cubic inches per pail for all tiles 3 x 6 inch and larger. A US gallon is 231 cubic inches, so the table is clearly a straight geometric calculation of one full gallon of grout. The calculator uses 231.2 cubic inches, the lowest value any cell implies, so it never shows more coverage than the data sheet. For 12 x 24 inch tile at 1/8 inch it gives about 274 sq ft against the table's 275.

Small mosaics are where the table is more generous than the formula. For 1 x 1 inch mosaic at 3/8 inch joints the table's 11 sq ft implies about 297 cubic inches, more than the pail holds; the formula gives about 8.6 sq ft. That is because the simple formula counts the corners where joints cross twice. On mosaics the calculator will therefore suggest a little more grout than the table, which is the safer direction.

Entering your tile and joint

Measure the actual tile, not the nominal size on the box. Many "12 x 24" porcelain tiles are 11 3/4 x 23 1/2 inches, and a smaller tile means slightly more joint per square foot. Use the tile thickness for the joint depth unless the joint will be shallower, for example where thinset squeezed up and was not raked out; a shallower joint needs less grout. Pick the joint width you will actually set with your spacers. The calculator only offers 1/16 to 3/8 inch because that is the range LATICRETE rates SPECTRALOCK 1 for.

A waste allowance of 10 percent covers what stays on the float, the sponge and the tile face. Uneven or hand-made tile with irregular joints, textured surfaces and first-time installers usually need more. Rustic tile with cushioned edges holds less grout per joint than its nominal size suggests, but the wavy joint lines often make up for it.

Working time and cure

Because it is pre-mixed, SPECTRALOCK 1 has no pot life in the usual sense, but the open pail skins over, so LATICRETE suggests resealing the pail between batches. Spread it diagonally across the joints with a firm rubber float, cut the excess off with the float edge held at 90 degrees, then start the first wash with a damp, well-wrung sponge about 5 to 10 minutes later, or within arm's length of what you have spread. Change the wash water every 50 sq ft. Do not add water to the grout and do not flood the joints during cleaning; LATICRETE says excess water can affect cure time and appearance.

The final clean is done once the joints are hard to the touch: about 45 minutes for 1/16 or 1/8 inch joints and about an hour for 3/8 inch joints, using a nearly dry white nylon pad followed by a clean cloth. Haze left the next day can be buffed off with a nylon pad. At 70°F the data sheet gives 6 hours to light foot traffic and 24 hours to heavy traffic, 14 days to full stain resistance and 28 days to full cure. At 50°F everything takes longer, with 48 hours before heavy traffic. Pools, fountains and steam rooms need 14 days at 70°F before use or filling.

Where not to use it

LATICRETE excludes areas exposed to harsh chemicals or aggressive cleaning such as steam cleaning, veterinary clinics and kennels, high-temperature areas, and floors and bases in the food preparation or cleaning areas of commercial kitchens. For those it recommends a grout that meets ANSI A118.5, such as SPECTRALOCK 2000 IG. Some soft polished marble, delicate glazed tile and glass tile can be scratched during installation, and white or porous stones such as Carrara or Thassos can change color, so test a small area first.

Check before you buy

The coverage figures are LATICRETE's approximations, and real use depends on how full you pack the joints, how much you wash out and how even the tile is. If the result lands close to a whole number of pails, buy one more; unopened pails keep for 18 months between 40°F and 75°F, and a matching color from the same batch is easier to find now than later. Always check the current data sheet on laticrete.com before a large order, as the figures can change between revisions.

FAQ

How much does a gallon of SPECTRALOCK 1 cover?

It depends on tile size and joint width. LATICRETE's data sheet gives 275 sq ft per 1 gallon pail for 12 x 24 x 3/8 inch tile with 1/8 inch joints, 549 sq ft at 1/16 inch and 92 sq ft at 3/8 inch. Larger tile goes further: 24 x 24 inch tile covers 412 sq ft at 1/8 inch. Mosaics use far more: a 2 x 2 inch mosaic at 1/8 inch covers 53 sq ft and a 1 x 1 inch mosaic 27 sq ft. LATICRETE calls these approximate figures.

Why are the numbers slightly different from LATICRETE's coverage chart image?

LATICRETE publishes the table twice: in the data sheet DS-36589-1026 and as a separate chart image, T-10831-FD-1025. Four rows match exactly, but for 3 x 6, 4 x 24, 6 x 24, 12 x 24 and 12 x 36 inch tile the image is 2 to 3 sq ft higher per cell (for example 277 against 275 sq ft for 12 x 24 at 1/8 inch). This page uses the data sheet, which carries the later revision code and gives the more cautious figures.

Can SPECTRALOCK 1 be used for 1/2 inch joints?

No. The data sheet rates it for joints from 1/16 to 3/8 inch (2 to 9 mm), and the coverage table stops at 3/8 inch, so the calculator does not offer wider joints. For wider joints choose a grout rated for them; LATICRETE's SPECTRALOCK PRO Premium epoxy, for example, is charted up to 1/2 inch.

Is SPECTRALOCK 1 an epoxy grout?

Not chemically. LATICRETE describes it as a patented pre-mixed grout with epoxy performance but without epoxy resins. It exceeds ANSI A118.19, the standard for ready-to-use grouts, and meets the ANSI A118.3 epoxy grout criterion for compressive strength (test 5.6). LATICRETE says the finished grout is equivalent to SPECTRALOCK PRO Premium, and it can be used in swimming pools and steam rooms after a 14 day cure at 70°F.

How long before I can walk on or wet SPECTRALOCK 1?

At 70°F (21°C) the data sheet gives 6 hours for light foot traffic and 24 hours for heavy foot traffic; at 50°F those stretch to 9 and 48 hours. Areas that will get intermittent water, such as a shower, need at least 24 hours at 70°F and 50% relative humidity. Submerged areas and steam rooms need 14 days, and acid cleaners should be kept off for 14 days.

LATICRETE and LATICRETE SPECTRALOCK 1 Pre-Mixed Grout are trademarks of their owner. This page is an independent estimate based on the published data sheet; check the bag label before mixing.