How Much Silicone Do I Need? Cartridges and Cartons per Metre, Window and Job
A 280 ml cartridge of silicone runs roughly 7.8 metres of a 6 x 6 mm joint, a 300 ml cartridge about 8.3 metres, and a 590 or 600 ml pack about 10 metres of a wider 10 x 6 mm joint, before waste. Measure the total joint length, add 10 to 15%, and divide by the figure for your pack and joint. A 1.2 x 1.5 m aluminium window sealed inside and out takes about one cartridge and one 590 ml pack; a bathroom or a kitchen worktop usually takes one or two cartridges.
The quick sum
The coverage figures on our product pages all come from one sum: pack volume in ml divided by joint width times depth in mm gives metres per pack. A 280 ml cartridge in a 6 x 6 mm joint is 280 ÷ 36 = 7.8 metres. On site you lose some in the nozzle, at corners and when tooling, so add 10 to 15%. Joint size matters more than brand: double the width at the same depth and you halve the metres per pack.
Metres per pack by joint size
These are the figures published on the product pages, before waste. A dash means the page does not publish a figure for that size.
| Joint (width x depth) | 280 ml cartridge | 300 ml cartridge | 590 / 600 ml pack |
|---|---|---|---|
| 6 x 6 mm | 7.8 m | 8.3 m | - |
| 9 x 6 mm | 5.2 m | 5.5 m | - |
| 12 x 6 mm | 3.9 m | - | - |
| 10 x 6 mm | - | - | 9.8 m (590 ml) / 10 m (600 ml) |
| 15 x 8 mm | - | - | 4.9 m (590 ml) / 5 m (600 ml) |
| 20 x 10 mm | - | - | 3 m (600 ml) |
The 12 x 6 mm and 20 x 10 mm figures come from Akfix 100E and Akfix 915N. The KNICKER 995 page publishes no coverage figure, so it is left out.
Width and depth: the 2:1 rule
Akfix recommend a width-to-depth ratio of about 2:1 for 915N, on joints between 10 mm and 35 mm wide, so a 20 mm joint should be about 10 mm deep, not 20 mm. For 100E they recommend a depth of 6 mm on joints 6 to 12 mm wide. As general guidance, an over-deep joint wastes silicone and copes less well with movement.
When to backfill first
Where a gap is too wide or deep for sealant alone, the Akfix 915N page advises filling it first with Akfix 805 PU foam, trimming the cured foam back and finishing over it with silicone. See how to use PU foam spray. Where the gap is only a little too deep, general site practice is to press a foam backer rod into it to set the depth, so you fill only the front of the joint.
Cost per metre
Prices at the time of writing. Cartridges are costed at 6 x 6 mm; the 590 and 600 ml packs at 10 x 6 mm, which takes about two-thirds more silicone per metre, so compare those with each other.
| Product | Per metre (single) | Per metre (carton) |
|---|---|---|
| ABC GP Fast-Curing 280ml | KSh 22 | KSh 21 |
| KNICKER GP 280ml | KSh 23 | KSh 19 |
| Akfix 100E 280ml | KSh 58 | KSh 51 |
| KNICKER High-Tech 300ml | KSh 48 | KSh 42 |
| ABC GP Structural 590ml | KSh 46 | KSh 41 |
| IG STAR Structural 590ml | KSh 46 | KSh 41 |
| Akfix 915N 600ml | KSh 95 | KSh 90 |
These products are not interchangeable; see which silicone sealant to use and structural vs ordinary silicone.
When a carton beats single pieces
| Product | Carton | Carton price | Works out per piece | Carton is cheaper from |
|---|---|---|---|---|
| ABC GP Fast-Curing 280ml | 24 | KSh 3,840 | KSh 160 | 23 pieces |
| KNICKER GP 280ml | 24 | KSh 3,600 | KSh 150 | 21 pieces |
| KNICKER High-Tech 300ml | 24 | KSh 8,400 | KSh 350 | 22 pieces |
| Akfix 100E 280ml | 24 | KSh 9,600 | KSh 400 | 22 pieces |
| ABC GP Structural 590ml | 20 | KSh 8,000 | KSh 400 | 18 pieces |
| IG STAR Structural 590ml | 20 | KSh 8,000 | KSh 400 | 18 pieces |
| KNICKER 995 Structural | 20 | KSh 9,000 | KSh 450 | 19 pieces |
| Akfix 915N 600ml | 12 | KSh 10,800 | KSh 900 | 12 pieces |
If your count is within two or three pieces of a full carton, buy the carton.
Worked jobs
These sizes are examples. On glazing, take joint sizes from the fabricator's drawing.
Aluminium window, sealed both sides
A 1.2 x 1.5 m window has a perimeter of 5.4 m. Say the outside joint is 10 x 6 mm in a 590 ml structural pack and the inside 6 x 6 mm. With 10% waste, that is 5.9 m each side.
- One window: 0.6 of a 590 ml pack outside, 0.8 of a 280 ml cartridge inside. Buy one of each.
- Ten windows: 59 m a side, so 7 packs of 590 ml and 8 cartridges; in ABC GP Structural and KNICKER GP, KSh 4,590.
- Thirty windows: 178 m each side, so 19 packs and 23 cartridges. Both cartons now win: KSh 8,000 for a carton of 20 against KSh 8,550 for 19 single packs, and KSh 3,600 for a carton of 24 against KSh 4,140 for 23 single cartridges.
Bathroom
Shower tray on two walls (1.8 m), basin back (0.6 m), WC base (1.4 m) and vanity top (1.2 m): 5.0 m, or 5.8 m with 15% waste. At 6 x 6 mm one 280 ml cartridge covers it. Let the joints creep out to 9 x 6 mm and you need two. In KNICKER GP that is KSh 180 or KSh 360.
Kitchen worktop
L-shaped runs of 3.0 m and 2.0 m, a 0.8 x 0.5 m sink rim (2.6 m) and two end joints (0.6 m): 8.2 m, or 9.0 m with 10% waste. At 6 x 6 mm that is two 280 ml cartridges, for example KSh 340 in ABC GP Fast-Curing.
Curtain-wall bay
A 3.0 x 3.0 m bay in four 1.5 m panes has 18 m of joints, or 20.7 m with 15% waste.
- At 15 x 8 mm: 20.7 ÷ 4.9 = 4.2, so 5 packs of 590 ml per bay. At 10 x 6 mm, 3 per bay.
- Ten bays at 15 x 8 mm: 207 m, so 43 packs of 590 ml. In ABC GP Structural or IG STAR, two cartons of 20 plus 3 singles costs KSh 17,350, against KSh 19,350 for 43 singles.
Cartridge gun or sausage gun
ABC GP and KNICKER GP 280 ml cartridges fit a standard cartridge gun. The IG STAR 590 ml sausage needs a sausage-type applicator gun; as general guidance, so do other sausage packs such as the Akfix 915N 600 ml.
For prices across the whole range, see silicone sealant price in Kenya.
Where to buy
Everything above is in our silicone sealants collection, with the structural range in structural silicone sealants. Collect from our Nairobi trade counter at Royal Business Park, opposite Complast, Old Mombasa Road, Monday to Saturday, 8:00 to 17:30, where pickup is free, or order for countrywide delivery at a flat KSh 350, free on orders over KSh 15,000. Send your joint lengths on WhatsApp and we will check the count. Fabricators and contractors buying by the carton can request a trade quote on our trade page.
Common questions
How many tubes of silicone do I need per window?
For a 1.2 x 1.5 m window, about one 280 ml cartridge inside at 6 x 6 mm and one 590 ml pack outside at 10 x 6 mm.
Is a 590 ml pack cheaper than two 280 ml cartridges?
It holds about the same as two cartridges, but the 590 and 600 ml packs here are structural or weatherseal silicones and the cheapest cartridges general-purpose ones. Choose the product for the joint first, then compare price.
Can I fill a deep gap with silicone alone?
As general guidance, no: an over-deep joint wastes silicone, and for 915N Akfix recommend a width-to-depth ratio of about 2:1. For a wide gap around a frame, the 915N page advises filling it first with PU foam, trimming it back and finishing with silicone; for a slightly deep joint, a backer rod sets the depth.