Janka numbers get quoted in showrooms with more precision than they deserve. The test measures how much force it takes to push a steel ball into the timber. That makes it a useful rough guide to dent resistance, but it is not accurate enough to split hairs between two mid-range hardwoods.
What Janka actually tells you
It is a dent-resistance test. It does not measure scratch resistance, and it will not tell you whether a dog or a set of heels will mark the floor.
Published figures are averages from lab samples. Within one species, even within one pack, boards vary. Grain, density, moisture content and which face is tested all shift the result. Arguing over 7.1 versus 7.8 is mostly noise.
Think in bands instead:
- Soft — dents show early under heels and heavy furniture
- Moderately hard — fine for most houses with pads and reasonable habits
- Hard — forgives more daily wear
- Very hard — where most Australian hardwoods sit; still marks under stilettos and grit
Common Australian (and imported) bands
These are relative bands only, the way the trade talks about them:
- Spotted Gum — very hard. One of the denser mainstream floor species. A good choice when kids, dogs and chair legs are the brief.
- Blackbutt — hard to very hard. Tough pale hardwood, though it still shows grit scratches in the coating like anything else.
- Jarrah — hard. Dense red-brown classic with strong dent resistance, though most people buy it for the colour.
- Messmate — hard, sometimes quoted as upper-moderate depending on the parcel. A feature-friendly member of the Victorian ash group.
- Tasmanian Oak / ash group (messmate, stringybark, alpine ash mixes) — moderately hard to hard depending on what is in the pack. Mixed-species cartons vary board to board, so ask what is actually shipping. See timber species names.
- European oak (common on imported engineered) — moderately hard. Softer than Spotted Gum or Blackbutt, but the default apartment choice because of its colour, grade range and availability.
Strand-woven bamboo can test very hard on paper. Treat it as its own product with its own wear behaviour, and judge it on more than the number.
How the bands play out in real houses
Most Australian hardwoods used for flooring sit in the hard or very hard bands. Plenty of moderately hard species and European oaks make excellent family floors too.
Soft species dent more easily. Some people like the lived-in look that develops. Others want maximum resistance for kids, dogs and chair legs. Be honest about the household before choosing a pale, softer imported species that photographs beautifully and bruises under a dining chair.
Commercial corridors and retail spaces need more thought than a spare bedroom. For domestic Melbourne living areas, moderately hard and up is usually fine with sensible care habits.
Finishes don’t harden the wood
Polyurethane, oil and hardwax protect the surface. They do not turn Messmate into Ironbark. Scratches in the coating are a different thing from dents in the timber, and both happen.
A hard floor with a soft film finish still shows chair-leg tracks in the coating. A softer oak with a tough commercial coating can look smarter for longer in a rental walkway, right up until something heavy dents the timber itself.
Care habits matter more than a 0.5 kN difference on a chart. See floor care and maintenance.
How to weigh hardness when choosing
Ask in this order:
- Lifestyle — stilettos, dogs, wheeled chairs, kids with toy cars?
- Species band — soft / moderate / hard / very hard for that lifestyle
- System — solid vs engineered for the subfloor (how to choose timber flooring)
- Finish system — repairability and sheen, remembering it adds no hardness
- Colour and grade — last, once the floor can survive the house
Stilettos, unpadded furniture feet and dragged fridges will mark almost anything. Harder timber forgives more, but not everything. Grit tracked in under shoes causes more scratches than anything else, on every hardness band.