Caulk Calculator
Tubes of caulk or sealant for a joint length, width and depth.
About this tool
Enter the total joint length, its width and depth, choose your tube or cartridge size and a waste allowance. The tool shows the number of tubes, the sealant volume, how far one tube covers and whether you need backer rod.
Estimating sealant
The sealant a joint needs is its volume: length Γ width Γ depth. A standard 300 ml cartridge fills about 8.3 m (27 ft) of a 6 Γ 6 mm joint, so 30 m of that joint takes 1.08 litres, four cartridges with 10% spare. A US 10.1 oz (299 ml) tube fills about 24 ft of a ΒΌ Γ ΒΌ in joint. Because volume depends on width Γ depth, doubling the joint width doubles the sealant, and a 12 Γ 12 mm joint takes four times as much as a 6 Γ 6 mm one. For joints wider than about 6 mm (ΒΌ in), press in closed-cell backer rod about 25% wider than the gap first. It controls the depth, saves sealant and lets the joint stretch without tearing, which happens when sealant sticks to three sides. A good rule is a joint about half as deep as it is wide, and at least 6 mm deep. Honest limits: real use varies with gap consistency, tooling and nozzle waste, so keep the allowance. Check the product's recommended joint size and movement capability. The tile calculator and the paint calculator are related.
Frequently asked questions
How much does a tube of caulk cover?
A 300 ml cartridge fills about 8 m of a 6 Γ 6 mm joint; a 10.1 oz tube about 24 ft of a ΒΌ Γ ΒΌ in joint.
How do I calculate how much caulk I need?
Multiply joint length Γ width Γ depth for the volume, then divide by the tube volume and add 10%.
When should I use backer rod?
For joints wider than about 6 mm (ΒΌ in), to set the depth and let the sealant flex.
How deep should a caulk joint be?
About half its width, but at least 6 mm (ΒΌ in).
Is my data sent anywhere?
No. Everything is calculated in your browser, and nothing is stored or sent.