Sealant volume calculator
Sealant needed for a joint of a given section, and how many cartridges that is.
Fill in the fields and the result will appear here automatically.
The real question in the shop is not "how many millilitres" but "will one cartridge do it". So next to the volume sits a row for how many metres of joint one cartridge fills: at a six-by-six section a 310 mL cartridge runs about eight and a half metres, at ten-by-eight less than four. The arithmetic is convenient: a millimetre by a millimetre by a metre gives exactly one millilitre.
How it works
Formula and logic
Rectangular section: v = b·t·L mL with b and t in mm and L in m, since mm²·m = mL. With reserve vₛ = v·(1 + w/100); cartridges = ceil(vₛ/C), coverage per cartridge = C/(b·t) m. Dimensions and C are positive, w ≥ 0 and values are finite. Whole cartridges are rounded before displaying volume, without deleting a genuine positive remainder. Concave bead shape and product-specific losses are not computed separately.
Example
A 6×6 mm joint 12 m long needs 475 ml with allowance — two 310 ml cartridges.
Fields and units
- Joint width — mm
- Joint depth — mm
- Joint length — m
- Cartridge volume — mL
- Allowance — %
How to use
- — Enter rectangular joint width and design depth in mm, selected for the actual product.
- — Enter total length in m and actual pack volume in mL.
- — Choose your reserve; it is not a guarantee against every loss.
- — Compare whole cartridges with geometric coverage per pack.
Method and limitations
- Calculation method
- Formula and logic
- Data or methodology source
- Sikaflex NP 2: product-specific joint depth and backer rod; not a universal consumption rule
- Limitation
- Concave bead shape and product-specific losses are not computed separately. Choose your reserve; it is not a guarantee against every loss.
FAQ
Why not make the joint deeper than it is wide?
There is no universal depth-to-width rule for every sealant. Dimensions depend on the product, movement and joint design. Sikaflex NP 2 instructions, for example, specify their own depths and limits; this calculator does not select them and only computes the entered rectangular volume.
What is a backer rod for?
In a suitable joint system a backer rod controls depth and separates sealant from the third surface. Sikaflex NP 2 specifies a rod or bond-breaker tape to prevent three-point bonding. Select compatibility and dimensions for the actual product; service life is not calculated here.
How accurate is the figure?
It is the geometry of a constant rectangular section. Joint variation, bead shape and packaging residue can change consumption. You select the reserve; it does not guarantee that every loss is covered.
Can I tell how many doorways one cartridge does?
The "metres per cartridge" row does it directly: divide it by the perimeter of your opening.