Caulk and sealant calculator
The joint section is what matters: width times depth times length.
Your inputs
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Example loaded. You can change any value.
There is no figure yet: nothing is calculated until you ask for it.
- Enter your measurements.
- Check the units and the assumptions.
- Press Calculate, or load the example.
Rather see a worked case? Press “Load example” and change any value afterwards.
Next step
Sealant closes the junctions; the joints between tiles are grout.
Where each number comes from Conversion constants are exact; densities and coverage rates come from cited sources; everything else is an assumption you can change. Methodology · Sources and updates
How to use it
- Measure the total length of joint you are sealing.
- Enter the joint width and depth in millimetres.
- Set the cartridge volume: 300 ml (about 10 fl oz) is standard.
- The result gives whole cartridges and metres per cartridge.
How it is calculated
A joint is a prism: length times width times depth. The only awkward part is the units, because length is in metres and the section in millimetres.
A 300 ml cartridge yields about 8.3 metres of 6 x 6 mm joint. Make the joint 10 x 10 mm and the same cartridge gives only 3 metres: the section grows with the square, not the side.
Which is why the golden rule of sealing is that a joint should be roughly twice as wide as it is deep. Too deep a joint does not just use more sealant: it flexes worse and cracks sooner.
Worked example
33 ft of 6 x 6 mm joint with a 300 ml cartridge and 10 % waste:
- Volume: 10 m x 0.006 x 0.006 = 360 ml
- With waste: 396 ml
- Cartridges: 396 / 300 = 1.32 → 2 cartridges
- Yield: 8.3 m (27 ft) per cartridge
This is a clean example of the difference between the mathematical result (1.32 cartridges) and what you buy (2), because sealant is not sold by the millilitre.
Good to know
- Twice as wide as deep. That ratio lets the sealant stretch without pulling off the edges. Backer rod makes it easy to achieve.
- An opened cartridge does not wait. Once started it skins over within days even capped. Plan to do all the joints in one session.
- Silicone, acrylic or polyurethane. Same calculation, different product. Silicone cannot be painted; acrylic can.
- Buy a spare. Running out mid-joint leaves a visible mark where you restart.
Frequently asked questions
How many feet does a tube of caulk cover?
A 300 ml (10 fl oz) cartridge gives about 27 ft of 6 x 6 mm joint, roughly 39 ft at 5 x 5 mm, and only 10 ft at 10 x 10 mm.
How many tubes of caulk do I need?
For 33 ft of 6 x 6 mm joint with 10 % waste you need 2 cartridges. The exact figure is 1.32, but fractions are not sold.
What shape should the joint be?
Roughly twice as wide as it is deep. That geometry lets the sealant follow movement without peeling away from the edges.
How much does a standard cartridge hold?
Between 280 and 310 ml (9.5-10.5 fl oz), with 300 ml the most common. Sausage packs for professional guns are usually 600 ml.