What's the difference between caulk and sealant?

Caulk is a rigid, often paintable filler suited to static interior gaps like skirting boards or trim, and it can crack if the joint moves. Sealant (silicone, polyurethane, or hybrid) stays flexible after curing, which makes it the right choice for joints that expand and contract or get wet, such as bathrooms, kitchens, and exterior gaps.

How much sealant does one tube cover?

It depends entirely on the joint's width and depth, not just its length — a wide, deep joint uses several times more sealant per meter than a narrow one. A standard 310mL cartridge covers roughly 8-9 linear meters of a small 3mm x 3mm bead, but only about 2-3 meters of a 6mm x 6mm bead; enter your own joint size above for an exact figure.

What sealant suits Malta's humid, salty climate?

A mould-resistant sanitary silicone is the standard choice for bathroom joints given Malta's humidity, and a UV- and salt-resistant sealant lasts longer on exterior joints exposed to strong sun and sea air.

Sealant Calculator — How Many Tubes Do I Need?

Sealant Calculator: How Many Tubes Do I Need?

Sealant is bought by the tube, but a joint is measured in meters — so it's easy to buy either too few tubes and get stuck mid-bead, or too many and waste an opened cartridge that skins over before the next job. This calculator takes your joint's length, width and depth, works out the total bead volume, and converts it straight into a tube or cartridge count for whichever pack size you're buying.

How to use the sealant calculator

Enter the joint length — the total run of the gap you need to seal.
Enter the joint width and depth, the bead's cross-section (for a typical fillet bead, depth is close to the width).
Add a waste percentage to cover cut ends, tooling-off excess, and part-used cartridges.
Choose a cartridge or sausage size, and a price per tube, for a tube count and a materials cost estimate.

The sealant calculation, explained

Sealant volume is simply length x width x depth, since a bead is a long thin rectangular prism. Unlike most materials in this calculator, waste here is applied by dividing rather than multiplying: adjusted volume = raw volume / (1 - waste%), so a 10% waste allowance increases the volume by about 11%. Tubes needed = adjusted volume / cartridge volume, rounded up to the next whole tube.

Worked example: a 10m joint with a 6mm width and 6mm depth, 10% waste, using 310mL cartridges.

Raw volume = 10m x 0.006m x 0.006m = 0.00036 m³ = 360 mL.
With 10% waste: 360 / (1 - 0.10) = 400 mL.
400 mL / 310 mL per cartridge = 1.29, which rounds up to 2 cartridges.

Pro tips and common mistakes

For joints wider than about 10mm or deeper than the sealant manufacturer recommends, pack a foam backer rod into the gap first. It stops the sealant bonding to the back of the joint, keeps the bead to the right hourglass profile, and uses noticeably less sealant than filling the full depth solid.

Worked example at Maltese prices: a 10m joint with a 6mm width and depth (10% waste, 310mL cartridges) needs 2 cartridges. At a typical price of around €5 per cartridge, that's about €10 in sealant for the job.

"Caulk" and "sealant" are often used interchangeably, but caulk is typically a rigid, paintable filler for static interior joints (skirting, trim), while silicone/polyurethane sealant stays flexible and is the right choice for joints that move or get wet — showers, expansion joints, and exterior gaps.