What density means
Foam density is the weight of foam in one cubic metre, written in kilograms per cubic metre (kg/m³). A higher number means more foam material in the same space. More material usually means the mattress keeps its shape longer and resists dips where you lie.
Density is not firmness. Firmness is how hard the surface feels. A dense foam can be soft (memory foam) and a light foam can feel hard at first. Density predicts how long the foam lasts; firmness decides comfort. See firmness by sleep position and weight.
Rough density guide
| Density (kg/m³) | What it usually is | Use |
|---|---|---|
| Under 20 | Light foam | Cushions, short-term use |
| 20 to 27 | Medium density | Kids, guest beds, occasional use |
| 28 to 35 | High density | Everyday adult sleep |
| Over 35 | Very high density or memory foam | Long life, orthopedic and memory foam layers |
These bands are a general guide used across the foam industry, not a Kenyan standard. Makers measure and name density differently, so always ask for the number in kg/m³.
Check a foam mattress's density at home
You can estimate density with a bathroom scale. Stand on the scale holding the mattress, subtract your own weight, then enter the result below. This works for all-foam mattresses only; springs and pillow-tops change the weight.
Method: density = weight ÷ (width × length × thickness). Inches are converted at 2.54 cm. The cover and quilting add weight, so the result reads slightly high.
Worked example
A 5 by 6 mattress, 8 inches thick, is 152 × 183 × 20.3 cm, which is about 0.565 m³. If it weighs 17 kg, its density is about 17 ÷ 0.565 = 30 kg/m³: high density, fine for everyday adult use. If the same mattress weighs 11 kg, it is about 19 kg/m³: light foam that will dent sooner.
Quick checks in the shop
- Lift a corner. At the same size and thickness, the heavier mattress usually has the denser foam.
- Press and release. Good foam springs back evenly. Foam that stays dented or crumbles at a cut edge is low quality.
- Ask for kg/m³. A seller who knows the number in writing is more trustworthy than one who only says "high density".
Ask us the density and weight of any Mattresses Kenya model on WhatsApp 0702 413 400.
Questions
What density is a high density mattress?
As a general industry guide, high density foam is about 28 to 35 kg/m³. Ask the seller for the exact figure in kg/m³.
Is high density the same as firm?
No. Density is how much foam is packed in; firmness is how hard it feels. Memory foam is dense but soft.
How can I check mattress density at home?
Weigh the mattress on a bathroom scale, then divide the weight by its volume in cubic metres. Our calculator does the maths for any Kenyan size and thickness.
Which density should I buy for daily use?
For an adult sleeping on it every night, choose high density foam or a spring or hybrid build. Medium density suits children and guest beds.