Mapei Grout Calculator: Ultracolor Plus FA, Keracolor and Kerapoxy Bags

1. Pick the MAPEI grout you plan to buy. A cement grout fills in its factor and a standard bag size. Flexcolor CQ and Kerapoxy CQ switch the tool to MAPEI's per-gallon coverage and give pails or kits.
2. Enter the tile length, width and thickness and the grout joint width. Use the real tile size from the box, and choose inches or millimetres first.
3. Enter the area to grout and your own waste allowance. Read the bags, pails or kits to buy, or switch the question to see the area one unit covers.

A MAPEI grout calculator estimates how much MAPEI brand grout a tiling job needs. It works out the volume of the grout joints, then turns that volume into the real purchase unit for the product you chose.

MAPEI sells grout two ways. The cement grouts, Ultracolor Plus FA, Keracolor S and Keracolor U, come as dry powder in bags, so the answer is pounds and bags. Flexcolor CQ is ready to use and Kerapoxy CQ is a two-part epoxy, so both are sold by the US gallon, as pails and kits.

This page is an independent tool. It is not affiliated with or endorsed by MAPEI. For a general calculator that is not tied to one brand, use the grout calculator, or compare the TEC grout calculator.

For a cement grout the calculator finds the cubic inches of grout in one square foot of tile, then multiplies by MAPEI's factor for the product.

Here L and W are the tile length and width in inches, T is the tile thickness, J is the joint width, and k is the grout factor in pounds per cubic inch. The 144 converts square inches to square feet.

1. Joint length. Each tile has a joint along its length and its width. Per square inch of tile, the joint length is (L + W) / (L x W).
2. Joint volume. Multiply by the joint width and the tile thickness, then by 144 to get cubic inches per square foot.
3. Pounds. Multiply by the grout factor k, then by the area and your waste allowance, and divide by the bag size.

I derived each cement factor from MAPEI's own coverage charts, read on 2026-10-04. For every chart row I computed the joint volume and divided the bag weight by the published square footage; the factor is the average of those rows.

Flexcolor CQ and Kerapoxy CQ are not weighed out this way. They are sold by volume, so the calculator reads MAPEI's published per-gallon coverage tables directly and reproduces the printed figures for the listed tile sizes. In between those sizes it scales by the same joint geometry.

The factor is not a measured bulk density. It is the grout weight that MAPEI's figures imply per cubic inch of finished joint. It folds in packing and mixing, so use it only with this formula.

Take a 400 sq ft floor of 12 x 24 in porcelain tile, 3/8 in thick, with 3/16 in joints, grouted with Ultracolor Plus FA in 25 lb bags. The 10 percent waste allowance is only an example.

1. Joint volume: 144 x 0.375 x 0.1875 x (12 + 24) / (12 x 24) = 1.2656 in3 per sq ft.
2. Grout per sq ft: 1.2656 x 0.0567 = 0.0718 lb. That is one pound for every 13.9 sq ft.
3. Whole floor: 400 x 0.0718 = 28.70 lb. Adding 10 percent gives 31.57 lb (14.3 kg).
4. Bags: 31.57 / 25 = 1.26, so buy 2 bags. About 18.4 lb is left over.

One 25 lb bag covers 25 / 0.0718 = 348.4 sq ft before waste. For the ready-to-use Flexcolor CQ on 12 x 12 in tile at 1/8 in joints, MAPEI lists 208 sq ft per US gallon, so a 150 sq ft floor with 10 percent waste needs 0.79 gal, rounded up to 1 one-gallon pail.

Coverage falls fast as the joint gets wider. Doubling the joint width halves the area a bag covers, because the joint volume doubles.

This table shows square feet per 25 lb bag of Ultracolor Plus FA, computed with the formula above. It matches MAPEI's own chart within about one percent for the listed sizes.

Bigger tiles cover far more per bag, because they have less joint per square foot. A 24 x 24 in tile has about one sixth of the joint length of 3 x 6 in tile over the same area.

Flexcolor CQ and Kerapoxy CQ are sold by the US gallon, not by weight, so MAPEI publishes coverage per gallon instead of a factor. The tables below are copied from MAPEI's data sheets, read on 2026-10-04. The calculator reads these numbers directly and scales between the listed tile sizes by joint geometry.

Flexcolor CQ: Square Feet per 1 US Gallon Pail

Ready-to-use grout for joints 1/16 to 1/2 in. The 2 gallon pail covers about twice these figures.

Kerapoxy CQ: Square Feet per 1 US Gallon Kit

Two-part epoxy grout for joints 1/16 to 3/8 in. The data sheet has no 3/16 in column, so the calculator interpolates between the 1/8 in and 1/4 in figures. The 2 gallon kit covers about twice these figures.

Coverage for an epoxy grout drops sharply on abrasive or slip-resistant tile faces, which hold more grout. Treat these as smooth-tile figures and buy a spare kit for rough tile.

Five inputs move the answer. Four of them are in the calculator, and the fifth is how well you spread the grout.

Joint Width

Grout quantity is directly proportional to the joint width. A 1/4 in joint takes twice the grout of a 1/8 in joint on the same tile.

Tile Thickness

Thicker tile means deeper joints. The calculator assumes the joint is filled to the full tile thickness, which is a safe figure for ordering.

Tile Size

Small tile has the most joint length per square foot. A mosaic can need many times the grout of a large-format tile.

Grout Product

The factor differs by product. Keracolor U unsanded uses 0.0421 against about 0.057 for the sanded cement grouts, so a pound of it goes further in the narrow joints it is made for.

Waste and Technique

Spillage, mixing loss and uneven tile edges use extra grout. Set your own allowance, since no standard figure fits every job.

MAPEI's grouts split into three families, and the calculator handles each in its own unit. The table lists what the data sheets say, read on 2026-10-04.

Pick the grout that suits your joint width first. If your product is not listed, choose Custom and enter a factor from its own data sheet. For a grout sold by the gallon, remember one US gallon is 231 cubic inches of finished joint when there is no loss.

Ordering Grout for a Floor or Shower

Enter the tile and joint details, pick the grout, and read the pack count. Then add the grout to the tile order from the tile calculator.

Checking a Store Estimate

If a store or installer quotes a count, run the same tile size here. A big gap usually means a different joint width or tile thickness.

Comparing Joint Widths

Change only the joint width to see the cost of a wider joint. The area per unit falls in direct proportion.

Planning a Whole Project

The flooring and tile quantities guide shows how to measure a room, and the how much grout guide explains the basics before you order.

1. Using Nominal Tile Size

Some tiles measure a little less than the label. Enter the real size from the box.

2. Forgetting Tile Thickness

A 1/2 in thick tile has joints twice as deep as a 1/4 in tile. Leaving thickness out of any grout estimate gives the wrong volume.

3. Using a Joint Width Outside the Product Range

Keracolor U is for joints up to 1/8 in. A wider joint needs a sanded grout, and the numbers for it do not apply.

4. Mixing the Units Up

Cement grouts are sold by the pound, while Flexcolor CQ and Kerapoxy CQ are sold by the gallon. The calculator shows the right unit for the grout you picked.

5. Skipping the Waste Allowance

The exact figure assumes no spillage. See the material waste guide for how allowances work.

6. Rounding Packs Down

Bags, pails and kits are sold whole. 1.4 units means 2. A full unit also mixes to a more even color than a part unit.

For the cement grouts the calculator reproduces MAPEI's printed coverage within about one to two percent. For Flexcolor CQ and Kerapoxy CQ it returns MAPEI's own chart numbers exactly at the listed tile sizes, and interpolates by joint geometry in between. Real jobs vary more than that.

The cement math uses the tile size, not the tile plus joint. Counting the joint corners exactly would lower the quantity by about 1.8 percent for the 12 x 24 in example and about 2.4 percent for 3 x 6 in tile with 1/16 in joints. MAPEI's per-gallon charts already fold in their own rounding, so for small mosaics at wide joints the chart can sit a little below plain geometry; the calculator follows the chart at those points.

It depends on tile size and joint width. For 12 x 12 in tile, 3/8 in thick, with 1/8 in joints, one 25 lb bag covers about 392 sq ft. Wider joints cut that number fast.

Pounds per square foot equal 144 x T x J x (L + W) / (L x W) x k. T is tile thickness, J is joint width, L and W are tile sides in inches, and k is the grout factor.

It uses 0.0567 lb per cubic inch of joint, derived from MAPEI's own coverage chart. Keracolor S uses 0.0583 and Keracolor U uses 0.0421.

Flexcolor CQ is ready to use and sold by the gallon, so the calculator reads MAPEI's per-gallon coverage table for your tile and joint, then divides your area by that figure and rounds up to whole pails.

Kerapoxy CQ is a two-part epoxy sold as a gallon kit. The calculator uses MAPEI's per-gallon grout chart for your tile and joint width, adds your waste allowance, and rounds up to whole kits.

MAPEI's chart gives Keracolor U more square feet per pound than the sanded grouts. That is the manufacturer's own data, not an error, and it only applies to the narrow 1/16 to 1/8 in joints it is made for.

Switch the units to millimetres and square metres. The calculator converts to inches with 1 in = 25.4 mm, then shows kilograms, litres and square metres beside the pounds, gallons and square feet.

Ultracolor Plus FA, Keracolor U, Flexcolor CQ and Kerapoxy CQ all list 1/16 in. Keracolor S starts at 1/8 in, so the verdict band warns you if you pick it for a narrower joint.

Yes. Pick Custom and enter the factor from that product's data sheet. You can also override the per-gallon coverage for Flexcolor CQ or Kerapoxy CQ by typing a value in the coverage box.

No. The calculation runs in your browser and nothing is sent to our servers. Anything you choose to Save stays in this browser only.

• Ultracolor Plus FA technical data sheet: coverage charts, joints, bag sizes (MAPEI, edition Aug 28, 2026, read 2026-10-04).
• Keracolor S Sanded Grout technical data sheet (MAPEI, edition Feb 26, 2026, read 2026-10-04).
• Keracolor U Unsanded Grout technical data sheet (MAPEI, edition Jun 29, 2024, read 2026-10-04).
• MAPEI Flexcolor CQ technical data sheet: per-gallon coverage table (MAPEI, edition Dec 10, 2025, read 2026-10-04).
• Kerapoxy CQ technical data sheet: per-gallon coverage table (MAPEI, edition Apr 29, 2026, read 2026-10-04).