Tell it the joint and the run, and it tells you how many sausages and how many cases to order. The arithmetic is the same one in our coverage article — a 20 fl oz sausage holds about 36 cubic inches of sealant, and the joint cross-section decides how far that goes.
Depth assumes you are holding it with backer rod. Without rod the sealant sinks to whatever depth the joint happens to be and the number roughly doubles.
Quick answers
How many linear feet does one 20 fl oz sausage cover?
About 48 feet of a 1/4" x 1/4" joint, 24 feet of a 1/2" x 1/4" joint, and 6 feet of a 1" x 1/2" joint. Multiply by 20 for a case.
How much extra should I order?
Ten percent on new work, closer to fifteen on a retrofit where the joint width varies along the run. Tooling loss is real and the drawing is not the building.
Does the backer rod change how much sealant I need?
Yes, and it is the biggest single factor. The rod sets the depth. A 1/2" x 1/2" joint with no rod takes twice the sealant of the same joint held at 1/2" x 1/4".
What diameter rod goes with my joint?
One size up from the gap, so it compresses in: 5/8" rod for a 3/8"–1/2" joint, 7/8" for 1/2"–3/4", 1-1/8" for 3/4"–7/8". The calculator names it for the width you pick.
What to do with the number
Under 20 cases, order it straight off the product page. From 20 cases the volume price applies itself in the cart — the tiers are published here. If the job needs more than a pallet, press Get Volume Pricing on the product and give us the quantity and the delivery ZIP.