Joint Filler Calculator: Gallons of Polyurea or Epoxy for Concrete Control Joints

1. Pick the filler. Its kit size fills in. Choose whether you know the joint length, or want it estimated from the floor area and joint spacing.
2. Enter the joint width and depth in inches. Use the saw cut size you measured, or the size on your specification.
3. Type your own overfill allowance. Read the kits to buy, and compare the coverage line with the data sheet chart.

A joint filler calculator estimates how much filler a concrete floor needs in its saw-cut control joints. It multiplies the joint length by the width and depth, converts cubic inches to gallons, and rounds up to whole kits.

Joint filler is not the same as joint sealant. The Metzger/McGuire sheets describe MM-80 and Spal-Pro RS 88 as semi-rigid fillers. They support wheel traffic and protect joint edges. The sheets state that neither is an elastomeric sealant, and that MM-80 is not designed for true expansion or isolation joints.

This page is an independent tool. It is not affiliated with or endorsed by Metzger/McGuire. For coatings by thickness, use the polyurea calculator. For slab volume, see the concrete calculator.

The calculator finds the volume of the joint and converts it to US gallons, then adds your overfill allowance.

1. Length. Enter it directly, or estimate it as 2 x area / spacing for a floor cut in both directions. The estimate ignores edge joints.
2. Volume. Width times depth gives cubic inches per inch of joint. Times 12 gives cubic inches per foot.
3. Gallons. One US gallon is exactly 231 cubic inches, according to NIST Handbook 44. Divide the volume by 231.
4. Overfill. The data sheets say to overfill, let the filler cure, then shave it flush. The allowance is yours.
5. Kits. Divide by the kit size and round up.

I read the coverage charts on 2026-10-03. The calculator uses the exact volume math, because the charts are rounded. The two agree within 3.7 percent on every MM-80 chart row.

Take a 10,000 sq ft warehouse floor saw cut both ways at 15 ft. The joints are 1/4 in wide and 1-3/4 in deep. The 10 percent overfill is only an example.

1. Length: 2 x 10,000 / 15 = 1,333 ft.
2. Volume per foot: 0.25 x 1.75 x 12 = 5.25 cu in.
3. Total volume: 1,333 x 5.25 = 7,000 cu in = 30.30 gal.
4. With overfill: 30.30 x 1.10 = 33.33 gal.
5. MM-80 in 1 gal kits: 34 kits, with 0.67 gal left.
6. RS 88 in 10 gal kits: 4 kits (40 gal). In 600 ml cartridges the same filler is 211 cartridges.

The MM-80 chart gives 45 ft per gallon for this joint, so the chart alone suggests 29.63 gal before overfill. The exact volume math gives 30.30 gal, about 2.3 percent more.

This table compares every row of the MM-80 chart with the volume formula. The Spal-Pro RS 88 chart rows I read match these figures.

The chart is rounded, usually up to a round number. The formula is exact for the joint size you enter, so the calculator uses it and shows the chart value beside it when the size is listed.

Five things move the answer. The calculator handles the first four.

Joint Depth

The data sheets call for full joint depth in saw-cut joints, or 2 in minimum where the cut is deeper. Depth changes the volume in direct proportion.

Joint Width

A 1/2 in joint takes twice the filler of a 1/4 in joint at the same depth.

Joint Length

Count every cut. Perimeter and construction joints add to a grid estimate.

Overfill

The sheets say not to fill flush and leave, because the filler can settle. Overfill, cure, then shave flush. Shaved filler is waste.

Backer Rod and Shrinkage Cracks

The sheets allow a 1/4 in layer of dry silica sand to choke off the base crack, and compressible rod only 2 in down in some joints. Those steps change the filler depth, so enter the true depth to fill.

Both sheets print the same coverage chart rows I read, but the products differ in chemistry, speed and kits.

Compare kit counts only after you convert to gallons. A 10 gal kit and ten 1 gal kits hold the same volume.

Quoting a Warehouse or Shop Floor

Enter the floor area and spacing for a quick length, then refine it with a joint count.

Ordering for a Garage

Use the known length and pick the 600 ml cartridge option for small jobs.

Comparing Kit Sizes

Change the kit size to see how many kits and how much leftover each pack gives.

Planning a Coating Job

Pair it with the resin and epoxy volume calculator for casting or coating volume.

1. Mixing Up Gallons and Kits

Kits come in set sizes. Round up after you convert.

2. Using the Wrong Depth

The filler depth is not always the saw cut depth. Enter what you fill.

3. Skipping Overfill

Filling flush and leaving it can leave low spots. Add an allowance.

4. Missing Perimeter and Construction Joints

The grid estimate covers interior cuts only.

5. Using Filler Where a Sealant Belongs

The sheets say MM-80 is not for true expansion or isolation joints. See the material waste guide for allowances.

6. Mixing Inches and Millimetres

This tool takes inches and feet. The sheet charts also list metric sizes, such as 6 x 25 mm at 24 m per gallon.

The volume math is exact for the dimensions you enter. The real uncertainty is in the joint itself, because saw cuts are rarely perfectly uniform.

Both sheets give metric rows too, in millimetres and metres per gallon. This calculator uses inches and feet, and shows metres and litres in the results.

It depends on the joint size. The data sheet lists 45 ft per gallon for a 1/4 x 1-3/4 in joint, 80 ft for 1/4 x 1 in and 100 ft for 3/16 x 1 in. The exact math gives 44.0, 77.0 and 102.7.

Multiply the joint length in feet by 12, then by the width and depth in inches, and divide by 231. Add your overfill allowance. The calculator does these steps for you.

About 1.95 gal, or 2.14 gal with 10 percent overfill. That is 3 kits of 1 gal or 14 cartridges of 600 ml.

For a floor sawn both ways at one spacing, length is about 2 x area / spacing. A 10,000 sq ft floor at 15 ft spacing has about 1,333 ft. Add perimeter and construction joints separately.

The data sheets say not to fill flush and leave, because low filler profiles are likely. You overfill, let it cure for 6 to 8 hours at minimum for MM-80, then shave or grind it flush.

No. The sheets describe MM-80 and RS 88 as semi-rigid fillers that support traffic and protect edges. They state RS 88 is not an elastomeric sealant and MM-80 is not for true expansion joints.

The sheets say full joint depth in saw-cut control joints, or 2 in minimum where the cut is deeper. Construction joints that are not saw cut get a 2 in depth. Check the sheet for backer rod rules.

MM-80 is sold in a 1 US gallon kit. RS 88 is sold in 10 gallon kits made of two 5 gallon pails, and in 600 ml dual cartridge kits.

Yes. Pick Other filler, then enter the kit size. The volume math works for any filler, but confirm the product coverage on its own data sheet.

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

• MM-80 technical data sheet: joint design, packaging and approximate coverage rates (Metzger/McGuire, revised 02/22, read 2026-10-03).
• Spal-Pro RS 88 technical data sheet: joint design, packaging and coverage chart (Metzger/McGuire, revised 7/20, read 2026-10-03).
• NIST Handbook 44, 2026 edition, Appendix C: the US gallon is 231 cubic inches exactly (NIST, read 2026-10-03).