Caulk calculator
Show the working — with your numbers
Length × bead section, padded by your waste and divided by the tube you type. Real beads are never perfectly even and gaps are rarely one width their whole length, and some sealant stays in the tube and the nozzle — a spare tube is cheap next to a second trip.
Type the total joint length, the bead width and depth, and the size printed on your tube. The tool works out the volume of sealant, adds the waste, rounds up to whole tubes and tells you how far one tube goes at that bead.
Worked example
Imperial: 60 ft of 1/4 × 1/4 in joint. Section 0.25 × 0.25 = 0.0625 in², × 12 in a foot = 0.75 in³ per foot, × 60 = 45 in³. With 10% waste 49.5 in³. A 10.1 fl oz tube is 10.1 × 1.805 = 18.23 in³, so 49.5 ÷ 18.23 = 2.72 — 3 tubes. One tube runs 18.23 ÷ 0.75 = about 24 ft of that bead.
Metric: 18 m of 6 × 6 mm joint. Section 36 mm², × 18,000 mm = 648,000 mm³ = 648 mL. With 10% waste 712.8 mL; ÷ 300 mL = 2.38 — 3 cartridges. One cartridge runs 300,000 ÷ 36 = 8,333 mm, about 8.3 m.
Corner fillet: 100 ft of 1/4 in bead around a tub and backsplash is a triangle, half of 0.0625 = 0.03125 in². × 1,200 in = 37.5 in³, + 10% = 41.25 in³, ÷ 18.23 = 2.26 — 3 tubes, each running about 48.6 ft. (In metric, 30 m of 6 mm fillet: 18 mm² × 30,000 mm = 540 mL, + 10% = 594 mL, ÷ 300 = 1.98 — 2 cartridges.)
On the job
Deep gaps eat tubes. A 1/2 in gap filled 1/2 in deep takes four times what a 1/4 × 1/4 in bead does. Push backer rod in first so the sealant sits at the depth the maker asks for — commonly about half the width — and the count drops, and the joint moves better too.
Cut the nozzle to the bead. The hole sets the bead. Cut it at the width you want, at an angle, and the length per tube is close to what the tool says. Cut it big "to go faster" and you tool half of it off into a rag.
Colour and cure are per lot. Buy the whole job at once, one colour, one product, and check the date on the tube — old silicone that will not cure is worse than none.
Quick referencefor caulk
- US fl oz
- 1.805 in³ · 29.57 mL
- 10.1 fl oz tube
- 18.2 in³ · 299 mL
- 1/4 × 1/4 in bead
- 0.75 in³ a foot — about 24 ft a 10.1 oz tube
- 6 × 6 mm bead
- 36 mL a metre — about 8.3 m a 300 mL cartridge
- mm² × m
- = mL · 1 mm² for 1 m is 1 mL
- Corner fillet
- half the width × depth section — twice the run
The formula
tubes = length × width × depth (× ½ for a fillet) × (1 + waste) ÷ tube volume
In imperial, feet × 12 × inches × inches is cubic inches, and a fluid ounce is 1.805 cubic inches. In metric, square millimetres × metres is millilitres. One tube's run is the tube volume divided by the bead section.
Questions
- How many feet does a tube of caulk go?
- It depends entirely on the bead. A standard 10.1 fl oz tube holds about 18.2 cubic inches, and a 1/4 × 1/4 in square bead uses 0.75 cubic inches a foot, so one tube runs about 24 ft. Halve the bead to 1/8 × 1/8 in and the same tube goes about 97 ft; double it to 1/2 × 1/4 in and it goes about 12 ft.
- How many tubes of caulk do I need?
- Joint length × bead width × bead depth gives the volume; add a little waste and divide by the tube. 60 ft of 1/4 × 1/4 in joint is 45 cubic inches; with 10% waste that is 49.5, and at 18.2 cubic inches a tube it rounds up to 3 tubes.
- How is a corner bead different from a joint?
- A bead run into an inside corner — a tub edge, a countertop backsplash, trim to wall — is a triangle in section, not a rectangle. Its volume is half the width times the depth, so pick the triangular fillet option and the same tube runs twice as far.
- How many mL is a tube of caulk?
- The common tube is 10.1 US fl oz, which is about 299 mL; the metric cartridge is 300 mL, and some are 280 or 310 mL. Sausage packs for a bulk gun are often 20 oz (about 590 mL) or 600 mL. Type the figure printed on yours.
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