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Flexcolor CQ Grout Calculator: How Many Gallon Pails?

Enter your area, tile size and joint width to see how many gallons of Flexcolor CQ to buy and which mix of 1 gallon and 2 gallon pails covers it. The numbers come from the per-gallon coverage chart in MAPEI's US technical data sheet MK 3000066 (edition date December 10, 2025). For 12 x 12 in tile with 1/8 in joints, MAPEI gives 208 sq ft per gallon; the calculator gives 200, slightly on the safe side.

MAPEI Flexcolor CQ coverage

Source: MAPEI Technical Data Sheet: MAPEI Flexcolor CQ Ready-to-Use Grout with Color-Coated Quartz (US, English), MK 3000066 (25-2622), edition date December 10, 2025, 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 gallon. 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 12 x 3/8 in tile with 1/8 in joints and 10% extra: 440 sq ft to grout. Each 12 × 12 in tile (144 sq in) carries (12 + 12) × 1/8 = 3 sq in of joint, 3/8 in deep. That works out to 1.13 cubic inches of grout per sq ft of floor. One 1 gal (3.79 L) pail fills about 225 cubic inches of joint at this tile size, so it covers 225 ÷ 1.13 = 200 sq ft. 440 ÷ 200 = 2.2 units of 1 gal (3.79 L) pail, or 2.2 × 1 gal = 2.2 gallons of mixed grout. In the sizes on sale, buy 1 × 2 gal pail + 1 × 1 gal pail (3 gal).

MAPEI Flexcolor CQ key specs

What Flexcolor CQ is

MAPEI Flexcolor CQ is a ready-to-use grout: it comes mixed in a pail, you spread it with a rubber float, and it cures as the small amount of water in the formula evaporates. "CQ" stands for color-coated quartz, the aggregate MAPEI uses to keep the color even from pail to pail. MAPEI positions it for porcelain, ceramic and natural-stone tile in homes and commercial jobs, inside and outside, on floors, walls, countertops and backsplashes. The data sheet also lists glass tile and mosaics, quarry tile, cement-based terrazzo and groutable luxury vinyl tile and plank.

The US technical data sheet (MK 3000066, edition date December 10, 2025) says it meets or exceeds ANSI A118.19, the standard for organic pre-mixed grouts. MAPEI markets it as stain and chemical resistant without a sealer, with BioBlock mold and mildew protection, and says it does not contribute to efflorescence. Because there is no water to measure and no mixing, the main question before buying is simply how many gallons the job needs.

How much one pail covers

The data sheet prints three coverage charts, one per pail size: 0.5 gallon (sold in Canada only), 1 gallon and 2 gallons (sold in the US only). Each chart lists seven tile sizes, from a 2 x 2 inch mosaic to 24 x 12 inch plank, against six joint widths from 1/16 to 1/2 inch. For the most common case, 12 x 12 x 3/8 inch tile with 1/8 inch joints, one gallon covers about 208 sq ft. Halve the joint to 1/16 inch and it doubles to 417 sq ft; widen it to 1/4 inch and it drops to 103 sq ft.

Tile size matters just as much. At 1/8 inch, a gallon covers 278 sq ft of 24 x 12 inch tile, 166 sq ft of 24 x 6 inch plank, 155 sq ft of 6 x 6 inch tile and only 50 sq ft of 2 x 2 inch mosaic. Small tiles have far more joint length per square foot, so a mosaic backsplash can need as much grout as a floor four times its size.

The 2 gallon chart is close to double the 1 gallon chart, usually within 2 percent, but for mosaics with wide joints it runs up to 14 percent higher. The 0.5 gallon chart is less regular. This calculator uses the 1 gallon chart throughout and counts a 2 gallon pail as exactly two gallons, which keeps the estimate on the cautious side.

How the calculator works

Grout fills the space between tiles, so the amount per square foot depends on joint length, joint width and joint depth. MAPEI's charts follow the textbook formula: cubic inches of grout per square foot = 144 x (L + W) x J x T / (L x W), where L and W are the tile length and width, J the joint width and T the tile thickness, all in inches. Dividing the volume a gallon fills by that figure gives square feet per gallon.

Working backwards from all 42 cells of the 1 gallon chart shows how much joint volume MAPEI assumes a gallon fills. For 12 inch and larger tile the answer is 225 to 235 cubic inches, close to the 231 cubic inches in a US gallon. For mosaics it falls to about 198, because more grout is lost on the tile face and in the many corners. One constant would either overstate mosaics or understate large tile, so the calculator uses five steps keyed to the tile's shorter side: 198 cubic inches below 4 1/4 inches, then 220.2, 222.0, 222.7 and 225.0 from 4 1/4, 6, 8 and 12 inches. Each step is the lowest value the chart implies for that size and anything larger, so the calculator never shows more coverage than MAPEI prints. For 12 x 12 inch tile at 1/8 inch it gives 200 sq ft per gallon against MAPEI's 208.

The calculator then adds your waste allowance, rounds up to whole gallons and picks the mix of 1 and 2 gallon pails with the fewest pails that leaves no more than one spare gallon.

Entering your tile and joint

Use the actual tile thickness, not the nominal one. Porcelain plank is often 3/8 inch, wall tile 1/4 inch and some large panels thinner still; grout depth scales with it, so an error here changes the result in direct proportion. MAPEI asks you to rake adhesive out of the joints so that at least two thirds of the tile depth is open for grout. If mortar has squeezed up and the joints are shallow you will use a little less, but plan on the full depth.

Joint width should be the real spacer size. A 1/16 inch joint uses half the grout of a 1/8 inch joint, so guessing one size wider can double the order. The calculator offers 1/16, 1/8, 3/16, 1/4 and 3/8 inch. The charts include a 1/2 inch column, but the data sheet's limitations say not to use Flexcolor CQ when the joint width or depth equals or exceeds 1/2 inch, so the calculator stops at 3/8 inch.

A waste allowance of 10 percent covers grout left on the float, in the bucket and in the wash water. Add more for textured, tumbled or heavily cushioned tile edges, which hold extra grout on the face.

Cure times and conditions

At 73°F (23°C) and 50 percent relative humidity, the data sheet allows light foot traffic after 24 hours, normal foot traffic after 2 days and heavy commercial traffic after 6 to 7 days. Full cure, and the stain resistance MAPEI advertises, takes 3 days, and the same 3 days are needed before showers or other intermittent water exposure. Because the grout cures by drying, it sets faster in dry air; MAPEI calls humidity below 50 percent ideal. Install only between 50°F and 95°F (10°C and 35°C) and keep pails from freezing.

Work in small areas. MAPEI says to spread and wash 10 to 15 sq ft at a time, starting the first wash before the grout skins over, and to finish by dragging a damp sponge diagonally across the joints. A milky film can appear afterwards and should clear in 20 to 30 minutes. Haze that remains can be removed with MAPEI's UltraCare Heavy-Duty Stone, Tile and Grout Cleaner.

Where not to use it

MAPEI rules out pools, hot tubs and other submerged installations, steam rooms and saunas, surfaces that stay at or above 140°F (60°C) such as hearths near wood stoves, and areas hotter than 125°F (52°C) in general. It is not for commercial kitchen floors or where no-rinse enzymatic cleaners are used; MAPEI points to its Kerapoxy IEG CQ epoxy for heavy industrial and kitchen work. Repeated steam cleaning or power washing is not recommended. It should not be used with pebble-stone or river-rock mosaics, irregular stone, or tumbled travertine whose pits you want to stay open. Glass mosaic and polished marble can be scratched or stained, so MAPEI says to test the color on a spare tile first.

Check before you buy

The coverage figures are MAPEI's approximations, and the data sheet says jobsite results vary with exact tile size and thickness, joint width and technique. Buy at least one spare pail of the same color and lot for touch-ups, and keep it sealed: shelf life is 18 months at 73°F if the lid stays closed. This page is based on the US English data sheet listed below; MAPEI updates its data sheets, so check the current edition on MAPEI's website before a large order.

FAQ

How much does a gallon of Flexcolor CQ cover?

It depends on tile size and joint width. MAPEI's US data sheet gives 208 sq ft per 1 gallon pail for 12 x 12 x 3/8 inch tile with 1/8 inch joints, 417 sq ft at 1/16 inch and 68 sq ft at 3/8 inch. Bigger tile goes further: 24 x 12 inch tile covers 278 sq ft at 1/8 inch. Mosaics use much more: a 2 x 2 inch mosaic at 1/8 inch covers 50 sq ft per gallon. MAPEI calls these figures approximate.

Is the 2 gallon pail exactly twice the 1 gallon pail?

Almost. The data sheet prints a chart for each pail size, and for most tiles the 2 gallon figures are 0 to 2 percent more than double the 1 gallon figures (838 against 417 sq ft for 12 x 12 tile at 1/16 inch). For mosaics with wide joints the gap grows to about 14 percent. The calculator uses the 1 gallon chart for both sizes, so a 2 gallon pail is counted as exactly two gallons, which is the cautious reading.

Can I use Flexcolor CQ for 1/2 inch joints?

The data sheet is contradictory. Its Where to Use section says joints from 1/16 to 1/2 inch, and the coverage charts have a 1/2 inch column, but the Limitations section says not to use it any time the joint width or depth equals or exceeds 1/2 inch. This calculator therefore stops at 3/8 inch. If your joints are 1/2 inch, ask MAPEI Technical Services (1-800-992-6273) before buying, or choose a grout rated for wide joints such as Ultracolor Plus FA.

Can Flexcolor CQ go in a shower or a pool?

Showers, tub surrounds and shower floors, yes: MAPEI lists areas with intermittent wet conditions and asks for a 3 day cure before water exposure. Pools, hot tubs and other submerged installations, no. MAPEI also does not recommend it for steam rooms or saunas, near fireplaces or wood stoves, or on commercial kitchen floors.

Why does the calculator use different numbers for mosaics and large tile?

MAPEI's chart implies that a gallon fills about 225 cubic inches of joint for 12 inch and larger tile but only about 198 for a 2 x 2 inch mosaic, where more grout is lost on the face and in the corners. The calculator uses the lower figure for tiles with a short side under 4 1/4 inches and steps up for 4 1/4, 6, 8 and 12 inch tile. Each step uses the lowest value in the chart for that size and up, so it never gives more coverage than MAPEI prints.

MAPEI and MAPEI Flexcolor CQ are trademarks of their owner. This page is an independent estimate based on the published data sheet; check the bag label before mixing.