A caulk calculator prevents you from making too many hardware store runs. Enter the length of the joint, the gap width, and gap depth and get back the volume of caulk you need, the number of tubes to buy, and a recommendation for the right caulk type — silicone, latex, or polyurethane — based on the application.
Joint Details
Recommended Caulk Type
Calculation Breakdown
How to Use the Caulk Calculator
Caulk is cheap per tube but easy to over- or under-estimate. A narrow 1/8" bead uses far less material than a 1/2" gap — the volume scales with the square of the gap dimensions, not linearly. This caulk calculator turns your joint length, width, and depth into an exact tube count with a recommended caulk type for your application.
Step 1: Select the Application Type
Choose the application from the dropdown. This determines the caulk type recommendation. Bathtubs and showers need 100% silicone or siliconized latex that resists continuous moisture. Exterior windows and siding call for a paintable polyurethane or premium latex. Interior baseboards and trim just need a basic paintable latex for a smooth, paintable seam.
Step 2: Enter Joint Length, Width, and Depth
Measure the total length of all joints to caulk. Select the gap width and depth from the dropdowns. For most interior trim work, a 1/4" × 1/4" joint is standard. Exterior gaps around windows or siding can range from 1/4" to 1/2". If your gap is wider than 1/2", use a foam backer rod first to reduce the effective caulk depth — this saves material and prevents the deep concave bead from cracking.
Step 3: Choose Tube Size
Standard 10.1 oz cartridges work with the most common caulk guns and are the most economical for medium-to-large jobs. Squeeze tubes (5.5 oz) are convenient for small repairs with no gun required. Sausage packs (20 oz) need a bulk-load gun but are more economical per ounce for large exterior projects. The calculator shows how many of each type you need based on your selected size.
Step 4: Read the Results
The results panel shows total volume in fluid ounces and milliliters, tubes to buy, feet of coverage per tube at your gap size, and total cost. The caulk type recommendation panel describes which product to look for and why it fits your application. Always buy one extra tube for touch-ups — leftover caulk stays usable for months in a properly sealed cartridge.
FAQ
Is this caulk calculator free?
Yes, the caulk calculator is completely free with no usage limits. All calculations run locally in your browser — no signup, no account, and no data ever leaves your device.
Is my project data private?
Yes, everything is calculated in your browser. Your dimensions are never sent to any server or stored remotely.
How do I calculate how much caulk I need?
Multiply your linear footage by the cross-sectional area of the gap (width × depth). A standard 10.1 oz cartridge covers approximately 30–50 linear feet for a 1/8" wide by 1/8" deep joint. The wider and deeper the gap, the fewer feet you get per tube.
What is the difference between silicone and latex caulk?
Silicone caulk is waterproof, flexible, and ideal for wet areas like tubs, showers, and exterior windows. It cannot be painted. Latex (acrylic latex) caulk can be painted, cleans up with water, and is best for interior joints like baseboards, crown molding, and trim. Polyurethane caulk is the strongest option for exterior gaps in siding, masonry, and foundations.
What size caulk tube should I buy?
Standard caulk guns use 10.1 oz cartridges, which are the most common and cost-effective for most jobs. Small squeeze tubes (5–5.5 oz) are available for tiny touch-up jobs. For large exterior projects, 20 oz sausage packs offer more material per dollar but require a bulk-load caulk gun.
How wide should a caulk joint be?
For most interior joints (baseboards, trim, countertops), aim for a joint no wider than 1/4 inch. Joints wider than 1/2 inch may crack as the caulk shrinks during curing. For wide gaps, use a backer rod (foam rope) to reduce gap depth before caulking, reducing the required caulk volume and improving long-term performance.
How long does caulk last?
High-quality silicone caulk can last 20+ years when properly applied. Standard latex caulk in dry interior areas lasts 5–10 years. Exterior and wet-area caulk typically needs inspection every 3–5 years. Signs of failure include cracking, shrinking away from the substrate, mold growth, or visible gaps.