A standard caulk cartridge holds 10.1 fluid ounces, which is about 18.2 cubic inches of sealant. How far that goes depends entirely on the joint: a 1/4 × 1/4 inch joint uses 0.0625 in² of sealant per inch of length, so one tube runs about 24 linear feet. A thin 1/8 inch bead goes four times as far, and a 1/2 inch joint uses four times as much. This caulk calculator converts your total joint length and bead size into tubes, for windows, doors, trim, siding, tubs and tile edges.
Tiling? The perimeter and change-of-plane joints get sealant, while the field joints get grout from the grout calculator.
How to use the caulk calculator
- Add up the total length of joints. For windows and doors, add the perimeter of each (for a 3 × 4 ft window, 14 ft), inside and out if you are sealing both sides.
- Enter the joint width and depth. For deep joints, push in backer rod first so the sealant depth stays shallow; then enter the sealant depth, not the gap depth.
- Choose "corner fillet" for a triangular bead in an inside corner, such as along a tub or countertop.
- Pick the tube size and add about 10% for tooling, nozzle loss and the end of the tube.
Formula
One US fluid ounce is 231 ÷ 128 = 1.805 cubic inches, so a 10.1 oz cartridge holds 18.23 in³ and a 28 oz cartridge 50.5 in³.
Worked example
Recaulking 10 windows that are each 3 × 4 ft (14 ft of perimeter), with a 1/4 × 1/4 inch joint, using 10.1 oz tubes and 10% extra.
- Length: 10 × 14 = 140 ft = 1,680 in.
- Volume: 1,680 × 0.25 × 0.25 = 105 in³; with 10% = 115.5 in³.
- Per tube: 18.23 in³ ÷ 0.0625 in² = 291.7 in = 24.3 ft.
- Tubes: 115.5 ÷ 18.23 = 6.3, so 7 tubes.
Linear feet per 10.1 oz tube
How far one standard cartridge runs for filled joints, no waste. Joints deeper than they are wide are not recommended, so those cells are left blank.
| Joint width | 1/8 in deep | 1/4 in deep | 3/8 in deep | 1/2 in deep |
|---|---|---|---|---|
| 1/8 in | 97.2 ft | — | — | — |
| 1/4 in | 48.6 ft | 24.3 ft | — | — |
| 3/8 in | 32.4 ft | 16.2 ft | 10.8 ft | — |
| 1/2 in | 24.3 ft | 12.2 ft | 8.1 ft | 6.1 ft |
Corner (fillet) beads use half the volume of a filled square joint of the same size:
| Fillet (triangle) bead | 10.1 oz tube | 28 oz tube |
|---|---|---|
| 1/4 × 1/4 in | 48.6 ft | 134.8 ft |
| 3/8 × 3/8 in | 21.6 ft | 59.9 ft |
| 1/2 × 1/2 in | 12.2 ft | 33.7 ft |
Joint design and backer rod
Sealant works best when it bonds to two sides of a joint, not three, and when it is not too deep. ASTM C1193, the standard guide for using joint sealants, recommends controlling sealant depth with a backer rod or bond-breaker tape, with depth generally less than the width for wider joints. For a typical 1/2 inch exterior joint, that means about 1/4 inch of sealant over a backer rod rather than filling the whole gap, which also halves the sealant you need.
Which sealant where
Use the sealant the job calls for: siliconized acrylic latex for interior trim you'll paint, 100% silicone for tubs, showers and glass, and polyurethane or hybrid sealants for exterior siding, concrete and masonry joints. Painting after? The paint calculator sizes the paint. Replacing siding? The siding calculator includes trim and accessories, and a newly stained deck may need sealant at the ledger and posts (see the deck stain calculator).
Caveats and assumptions
- Bead sizes in real life are rarely perfectly uniform; the waste allowance covers some variation.
- Very wide joints (over about 1 inch) may need special sealants or a different detail. Follow the product data sheet.
- Check sealant compatibility with the surfaces, and with paint if you plan to paint over it.
- Squeeze tubes and specialty cartridges vary in size; read the volume on the label.
Frequently asked questions
How many linear feet does a tube of caulk cover?
A 10.1 oz tube runs about 24 ft at a 1/4 × 1/4 inch joint, about 97 ft for a 1/8 × 1/8 inch bead and about 6 ft for a 1/2 × 1/2 inch joint.
How many tubes of caulk for a window?
A 3 × 4 ft window has 14 ft of perimeter. At a 1/4 inch joint that is about 0.6 of a 10.1 oz tube per side, so one tube per window if you seal inside and out.
How many tubes of caulk do I need for a bathtub?
A standard 5 ft tub against three walls has about 12 ft of joint. A 1/4 inch fillet bead uses about a quarter of a 10.1 oz tube, so one tube is plenty, with some left for the surround.
How much caulk is in a tube?
A standard cartridge holds 10.1 fluid ounces, about 18.2 cubic inches or 299 mL. Larger 28 oz cartridges hold about 50.5 in³.
How deep should caulk be?
For narrow joints, about as deep as wide up to 1/4 inch. For wider joints, ASTM C1193 guidance is generally a depth about half the width, controlled with backer rod.
Sources
- ASTM C1193 — Standard Guide for Use of Joint Sealants — joint width-to-depth guidance and backer rod
- NIST — Handbook 44 (specifications and tolerances, including unit equivalents) — 1 gallon = 231 in³ = 128 fluid ounces
- DAP — Caulks and sealants — cartridge sizes and product selection
This calculator gives estimates for planning and education. Check measurements, local codes, supplier specs and your school's official policy before relying on a result. See our disclaimer and how we build and check calculators.