How many tubes of caulk or silicone sealant do you need? Add your joint lengths and dimensions to estimate volume, whole cartridges and material cost. Combine several joint sizes in one purchase calculation, or use matching manufacturer coverage.
How to use the sealant calculator
- Choose units for the run length and the joint size. You can enter feet and inches or metric measurements.
- Add a joint group. Enter the length of one run and how many identical runs you have. Select a rectangular joint, a right-angle triangular fillet or manufacturer coverage.
- Enter the filled joint dimensions. For manufacturer coverage, enter the length covered by one pack at exactly your joint size and application.
- Read the net pack volume from the label. Set an additional allowance and any usable matching sealant you already have.
- Optionally enter the pack price, then select Calculate sealant. The result gives new whole packs, volume, coverage by group and purchase cost.
Enter decimals with a point or comma. Do not use fractions such as 1/4 or thousands separators. For a quarter-inch joint, enter 0.25 in. Changing units converts the existing related values. Changing the currency does not change your price. Recalculate after editing.
Which joint shape should I choose?
A rectangular joint is estimated from its width and the depth actually occupied by sealant. If backing material limits the depth, enter the sealant depth above it, not the whole empty cavity.
A triangular fillet is estimated as a right triangle between two surfaces that meet at 90 degrees. Enter the two legs measured along those surfaces. Do not enter the diagonal exposed face as a leg. The two legs may have different lengths.
A tooled concave bead is not a perfect triangle. A rounded backing rod also changes a filled profile. A hidden gap behind a corner bead adds material that a simple triangle does not include. Where shape or application differs substantially, use matching manufacturer coverage or a measured trial instead of assuming the geometry is exact.
How much sealant does a joint use?
For dimensions in millimetres and length in metres, the theoretical volume is especially simple:
- Rectangular joint: volume in mL = width in mm × filled depth in mm × total length in m.
- Right-angle triangular fillet: volume in mL = first leg in mm × second leg in mm × total length in m ÷ 2.
- Total length for a group = length of one run × number of identical runs.
- With manufacturer coverage: volume = total group length ÷ coverage length per pack × pack volume.
One square millimetre of cross-section over one metre of length has a volume of one millilitre. For example, a 6 × 6 mm rectangular joint uses 36 mL per metre before losses. A triangular fillet with two 6 mm legs uses 18 mL per metre in this simplified model.
After adding the volumes of every group, the calculator adds your allowance, subtracts usable stock and rounds the remaining need up to whole packs. It does not round each group's purchase separately.
New packs = round up [max(0, total base volume × (1 + allowance ÷ 100) − usable stock) ÷ net volume per pack].
Example: two joint sizes and 300 mL cartridges
Suppose you need 10 m of rectangular joint measuring 6 × 6 mm and 5 m of triangular fillet with two 6 mm legs. These are example dimensions, not an installation recommendation.
- Rectangular group: 10 × 6 × 6 = 360 mL.
- Triangular group: 5 × 6 × 6 ÷ 2 = 90 mL.
- Base total: 360 + 90 = 450 mL.
- With a chosen 10% allowance: 450 × 1.10 = 495 mL.
- With no existing stock: 495 ÷ 300 = 1.65, so buy 2 cartridges.
Two cartridges provide 600 mL, which is 105 mL above this estimate. At an illustrative price of EUR 8 each, the purchase costs EUR 16. With 200 mL of usable matching stock, the shortfall would be 295 mL and one new cartridge would cover the estimate. Load example fills these values without the stock deduction.
How far does one tube of silicone go?
Coverage depends on the actual cross-section and pack volume. For a 300 mL cartridge and a 6 × 6 mm rectangular joint, theoretical coverage is 300 ÷ 36 = 8.333 m. With a 10% allowance, the planning coverage becomes 300 ÷ (36 × 1.10) = 7.576 m.
For a triangular fillet with two 6 mm legs, the same model gives twice that theoretical length because its cross-section is half as large. This does not mean that every corner seal uses half the material in practice. Tooling, gaps and bead shape still matter.
The results show coverage for each group separately. Each figure assumes the entire pack is used for that group alone. Do not add the coverage lengths together. Read the new pack count for your combined purchase.
What allowance should I use?
The initial 10% is an editable estimate, not a universal rule. Starts and stops, material left in the nozzle, cleanup, uneven gaps and difficult access change losses. Short scattered joints may have a different loss rate from one steady run.
Choose an allowance suited to your work or follow the product supplier's estimating advice. If manufacturer coverage already includes waste, add only any further reserve you actually want. Avoid counting the same loss twice.
Are US fluid ounces the same as ounces on the label?
Not always. This calculator's US fl oz option measures volume. One US fluid ounce equals 29.5735295625 mL. A 10.1 US fl oz cartridge therefore contains about 298.693 mL. It is close to, but not exactly, 300 mL.
Weight ounces and grams measure mass. Imperial fluid ounces also have a different volume. If the label gives only mass or Imperial units, use the manufacturer's stated mL volume. Do not assume that a 300 g pack contains 300 mL. In mL mode, enter the actual volume printed on the pack, including larger foil packs where appropriate.
Can I combine different products or colours?
Use separate calculations for different sealant products or colours. The combined total assumes material can be shared between all listed groups. The purchase calculation also assumes one pack size and one price per pack.
Count old material only when it remains usable, matches the product and colour, and has been stored within the product's requirements. A blocked or cured partly used tube may contain less usable material than its original label suggests. Enter the usable remaining volume, not the original capacity.
Does this calculator choose the right joint depth?
No. Use the joint detail and the sealant manufacturer's application instructions. Width, depth, backing, movement and substrate compatibility are related. A volume estimate cannot determine whether a bead will bond, accommodate movement or provide the required seal.
Do not make a joint shallower or narrower just to use fewer cartridges. This tool does not specify backing rod diameter, primer, cure time, fire protection, structural glazing or a waterproofing system. For non-rectangular cavities and other complex profiles, use product-specific coverage or a measured trial.
Check product coverage before buying
Manufacturer resources can help you compare your assumptions. Bostik's joint sealant calculator distinguishes square and triangular profiles. Sika's joint sealing coverage chart gives length coverage by joint size and pack volume. Pereseal's quantity calculator explains rectangular volume and pack rounding. Use the current documentation for the product you will actually buy.
For the rest of a tiling project, use our tile calculator and grout calculator. The generated photo illustrates a sealing project and does not define a recommended product or joint dimension.
