Quick answer
On the Janka scale, spotted gum (about 11 kN) is the hardest common flooring timber in this chart, followed by blackbutt (about 9.1 kN) and jarrah (about 8.5 kN). Tasmanian oak (5.5–7 kN) and European oak (about 4.2–6.1 kN) are moderate. Rimu is softer still on published figures. Harder timbers dent less, but hardness doesn't decide scratch resistance, stability, appearance or how long a floor lasts.
Janka hardness is a standard test that measures the force needed to embed an 11.28mm steel ball to half its diameter into a sample of wood (Wikipedia – Janka hardness test). The higher the number, the more force it takes to dent the timber.
Janka hardness chart (kN)
| Species | Janka (kN) | ≈ lbf | Origin | Typical flooring use | Source |
|---|---|---|---|---|---|
| Spotted gum | about 11 | ~2,470 | Eastern Australia | Straight boards, high-traffic areas | PFC |
| Blackbutt | about 9.1 | ~2,050 | NSW / south-east QLD | Straight boards, light-coloured floors | PFC |
| Jarrah | about 8.5 | ~1,910 | South-west WA | Boards; heritage floors; recycled | PFC |
| Tasmanian oak (3 eucalypts) | 5.5–7 | ~1,240–1,570 | Tasmania (and Victoria) | Straight boards, stained floors | PFC, Flooring Expert |
| European oak | about 4.2–6.1 | ~940–1,370 | Europe | Boards, herringbone, chevron, parquet | Flooring Expert, PFC |
| Rimu | about 3.6 (supplier figure) | ~810 | New Zealand | Heritage boards; recycled | Plantation Bamboo |
The lbf column is a conversion (1 kN ≈ 224.8 lbf), rounded. Rimu's figure comes from a single NZ supplier's published comparison and should be treated as indicative only. Want more detail on a species? See European oak vs spotted gum, vs blackbutt, vs Tasmanian oak, vs jarrah and oak vs rimu.
How the Janka test works
The test presses a steel ball 11.28mm in diameter (giving a contact area of 100mm² at half depth) into the side grain of a timber sample and records the force needed (Wikipedia). Australia reports the result in kilonewtons; North America uses pounds-force. Samples are tested at a set moisture content, commonly around 12%, which is close to the moisture content of an in-service floor. Australian interiors typically sit at 8–14% equilibrium moisture content (WoodSolutions).
What Janka tells you
Janka is a good guide to dent resistance. A higher number means the timber better resists:
- stiletto heels and narrow chair legs,
- dropped objects such as pans and toys,
- heavy furniture on small feet.
That's why spotted gum and blackbutt are popular in busy family homes, and why softer timbers like European oak benefit from felt pads and entry mats.
What Janka doesn't tell you
The Janka number is useful but narrow. It does not measure:
| Not measured by Janka | What actually decides it |
|---|---|
| Scratch resistance | Mostly the finish – type, number of coats, sheen |
| Dimensional stability | Species movement, format, moisture content and installation |
| Appearance and colour | Species, grade and finish |
| How long the floor lasts | Thickness of usable timber (solid vs engineered) and how often it can be re-sanded |
| Water resistance | Finish, maintenance and how quickly spills are wiped up |
| Ease of installation and sanding | Very hard timbers are harder to machine, sand and fix |
Three more caveats:
- Values vary. Timber is natural. Trees, growth regions and moisture content all change hardness, which is why European oak is quoted as a range (about 4.2–6.1 kN) rather than one number, and why different sources disagree.
- Marks show differently. On a mid-tone oak with visible grain, small dents blend in. On a smooth, dark or high-gloss floor, the same dent is more obvious.
- Harder isn't always better. Very hard timbers can be harder work to sand and fix, and the hardness advantage counts for little if the finish is wrong for the household.
Where European oak sits – and why it's still a premium floor
European oak is moderately hard, not super-hard, yet it is widely chosen for premium floors. Its strengths are elsewhere: a calm, even grain that suits herringbone and chevron, consistent colour, and a wide range of finishes from white to smoked. A good finish and sensible habits – felt pads, mats, prompt cleaning – deal with most wear. When it does wear, solid oak can be sanded and recoated – see solid vs engineered oak.
Engineered, hybrid and laminate
- Engineered oak has the same surface species, so the same rated hardness, though dent behaviour also depends on top-layer thickness and the core.
- Hybrid and laminate aren't timber and aren't rated on the Janka scale. Laminate uses abrasion classes; hybrid is judged by wear-layer specifications. Compare them using the right measures – see solid oak vs hybrid.
Which should you choose?
- Large dogs, heavy use, hardness above all: spotted gum or blackbutt.
- Pattern floor with a calm, European look: European oak with a durable finish – see timber floors and pets for practical tips.
- Heritage home: match the existing species (jarrah, rimu, Tasmanian oak) and restore where possible.
Timbo supplies Prime grade European solid oak parquet to the trade. Homeowners can find a Timbo partner; flooring businesses can become a partner.
Sources
- Wikipedia – Janka hardness test
- PFC – Janka rating and floor durability
- Flooring Expert – European oak vs Australian hardwood
- Plantation Bamboo – flooring brochure (rimu, supplier figure)
- WoodSolutions – moisture guide
Frequently asked questions
What is a good Janka rating for flooring?
There is no single pass mark. Timbers from about 4 kN (such as European oak) to 11 kN or more (such as spotted gum) are all used successfully for floors. Softer timbers dent more easily under point loads, so they suit households that use felt pads, mats and a durable finish.
What is the Janka hardness of European oak?
About 4.2–6.1 kN, according to Australian flooring sources. That's moderate: harder than many softwoods and similar to Tasmanian oak, but softer than spotted gum, blackbutt and jarrah.
Does a higher Janka rating mean fewer scratches?
Not really. Most everyday scratches are in the finish, not the timber, so the coating matters more than the species. A higher Janka rating mainly means fewer dents from heels, chair legs and dropped objects.
How do I convert Janka kN to lbf?
Multiply kN by about 225. For example, 5 kN is roughly 1,120 lbf and 11 kN is roughly 2,470 lbf.
Does engineered oak have the same Janka rating as solid oak?
The oak surface is the same species, so its rated hardness is the same. How the floor resists a heavy dent can also depend on the thickness of the top layer and the core beneath it.
Do hybrid and laminate floors have a Janka rating?
Not in a comparable way. Janka is a test for timber. Laminate is rated by abrasion classes (AC ratings) and hybrid by wear-layer thickness and other product tests, so you can't compare them with timber on the Janka scale.