Caulk Amount Estimator
Enter the total seam length and the bead width you plan to lay to see how many cartridges to buy.
Caulk needed
Why bead width matters so much
Doubling a bead's width doesn't double the caulk it uses — it roughly quadruples it, because the cross-section area scales with the square of the width. A slightly too-wide bead is one of the most common reasons a tube runs out halfway through a job, so it's worth tooling beads as narrow as the gap allows rather than laying it on thick out of caution.
The estimate assumes a clean, evenly tooled bead. A shaky hand, an over-squeezed gun, or a gap that varies in width along its length will all use more caulk than the math predicts — buy the rounded-up number, not the bare minimum.
Frequently Asked Questions
How do I measure my total bead length?
Add up the length of every seam or joint you're sealing — around a tub, along a countertop backsplash, around a window frame, and so on. Measure each run with a tape measure and sum them; there's no need to account for corners separately since the tape follows the same path the caulk bead will.
How is the coverage per tube calculated?
A wet caulk bead is roughly triangular in cross-section once it's tooled, so the estimator treats its area as width² / 2. Dividing a standard 10.1 fl oz cartridge's volume (about 18.2 cubic inches) by that cross-section area gives the linear length one tube can lay down — a wider bead uses far more caulk per foot than a narrow one, since the area grows with the square of the width.
What bead width should I use?
Match the gap you're filling: a tight seam (tile-to-tile, trim edges) often takes a 1/8 inch bead, a typical tub or sink joint runs about 1/4 inch, and a wider gap around a window or door frame might need 3/8 inch or more. When unsure, a slightly wider bead is easier to tool cleanly than a starved one.
Should I buy exactly the number of tubes calculated?
Round up and keep the spare — caulk cartridges keep reasonably well once opened if you cap the tip, and running short mid-bead leaves a visible seam where you stopped and restarted. It's also worth having one extra tube on hand for a job that runs longer than expected.
Planning estimate only, based on a standard 10.1 fl oz cartridge and a tooled triangular bead. Actual usage varies with technique and the material you're sealing.