The knee to wall test is the one ankle measurement you can take at home that gives a real number instead of a band. It needs a wall, a ruler and about two minutes. It reads ankle dorsiflexion — the shin travelling forward over a planted foot — one side at a time, in centimetres.
That precision is the point of the test and also its risk. On Limber's scale a single centimetre moves the score by five to ten points, so the care you take over foot placement matters more here than anywhere else in the battery.
The short answer
- Half-kneel facing a wall, front toe touching it. Drive the knee to the wall with the heel down, then walk the foot back until the knee only just touches.
- Measure from your big toe to the wall, round to the nearest centimetre, then do the other side.
- 0–2 cm reads 15 · 4 cm reads 35 · 6 cm reads 55 · 8 cm reads 70 · 10 cm reads 85 · 12 cm and over reads 95. Straight lines between those marks.
- One centimetre is worth 5 to 10 points. Limber calls a 12-point gap between your sides an imbalance, so a centimetre of careless foot placement manufactures most of one out of nothing.
- The published error on this test runs to about a centimetre or two — 5 to 20 points on our own scale. Read every gap you find against that.
How to take the knee to wall test
These are the app's own setup lines, and this page prints them word for word, because a reading is only comparable to another reading taken the same way.
- Face a wall in a half-kneeling stance, front toe touching it.
- Drive that knee to the wall with the heel down, then walk the foot back until the knee only just touches. Stop at a stretch, never at sharp pain.
- Keep the heel down. Measure from your big toe to the wall.
- Round to the nearest centimetre, then do the other side.
Three details decide whether two readings can be set beside each other.
The heel stays flat. The moment it lifts you are measuring something else, and the number can gain several centimetres with no change in the ankle at all.
The foot stays square to the wall. Turn it out and the same ankle reads further.
The knee tracks over the second toe rather than falling inward, for the same reason.
Take both sides every time. Limber stores them separately, because an ankle that gives 9 cm and an ankle that gives 4 cm is not a body with a 6.5 cm ankle.
You can take the reading here. The knee-to-wall test puts the stepper, the score and both sides on one page, and nothing is stored and nothing is sent anywhere.
What each centimetre scores
Six anchors, on the same 0–100 scale the app uses.
| Toe to wall | Score | What the scale is doing |
|---|---|---|
| 0–2 cm | 15 | Floor — flat below here |
| 4 cm | 35 | Anchor |
| 6 cm | 55 | Anchor |
| 8 cm | 70 | Anchor |
| 10 cm | 85 | Anchor |
| 12 cm and over | 95 | Ceiling — flat above here |
Between two anchors the score runs in a straight line, so 7 cm reads 63, 9 cm reads 78 and 11 cm reads 90. The stepper runs 0 to 20 cm.
This is the only interpolating instrument on the site, and the reason is narrow: it is the only reading in the battery that is a measured length. A length can sit between two marks. A band cannot, and the app does not pretend it can — the toe touch, the shoulder reach, the hip flexor and the deep squat all step from one anchor to the next with nothing in between.
Outside the anchors the scale goes flat on purpose. Nought, one and two centimetres all read 15; everything from twelve upward reads 95. Below 2 cm the knee is barely clearing the toe and the test has stopped separating readings. Above 12 cm it has stopped measuring you. A scale that kept climbing past that point would be claiming precision the measurement does not have.
A centimetre is worth 5 to 10 points
Work the arithmetic out and it is uncomfortable.
One centimetre is worth 5 to 10 points — ten through the middle of the scale, where 4 cm reads 35 and 6 cm reads 55, and five at the top, where 10 cm reads 85 and 11 cm reads 90.
Limber's imbalance threshold is 12 points. So a centimetre of careless foot placement manufactures most of an imbalance out of nothing. Two centimetres of it, taken through the steep middle of the scale, manufactures an imbalance and a half.
That is not an argument against the test. It is an argument for the tape, the flat heel and the square foot, and for taking both sides in the same session rather than one today and one on Thursday.
The gap this test can express
Here is the other half of the same idea, and it runs the opposite way.
Three of Limber's five built tests are recorded per side. What each can express as a difference between your two sides is fixed by how the reading is built.
| Test | Smallest gap it can show |
|---|---|
| Knee to wall | 5 points |
| Shoulder reach | 20 points |
| Hip flexor | 30 points |
This is the only per-side test in the battery that can express a gap smaller than the imbalance threshold. On the banded tests — shoulder reach steps 20 to 25 points a band, hip flexor 30 to 35 — the smallest gap the instrument can express already exceeds our own 12-point line, so any difference at all is flagged.
Two rules follow, and they reach the same place from opposite directions.
On a banded test, a one-band difference means re-measure, not finding. The instrument cannot show you a small gap, so it shows you a large one whether or not there is one.
On this test, a one-centimetre difference means the same thing, for the opposite reason: a centimetre sits inside the measurement's own error. One side more flexible than the other works through what to do with a gap that survives a second session.
What the evidence says
Start with the finding that goes against us.
Powden, Hoch and Hoch reviewed the weight-bearing lunge test in Manual Therapy in 2015. It is reliable when the same person repeats it — and the minimal detectable change values reported sit in the region of a centimetre to two. On Limber's scale that is 5 to 20 points: as large as the imbalance threshold itself, and at the top end well past it. A one-centimetre difference between two of your own readings is not a change. It is the instrument.
Grade: solid, and it constrains what this page may claim. Nothing here says a centimetre is an improvement.
The reliability finding is better news. Bennell and colleagues reported good intra-rater and inter-rater agreement for the weight-bearing lunge in the Australian Journal of Physiotherapy in 1998 — good enough to compare your own readings over time, which is all we use it for.
Grade: reasonably solid, and narrow. Repeatability is not accuracy, and agreement between two raters in a study is not agreement between you in March and you in April.
One more, because people bring a physiotherapist's number to this test and ask why the two disagree. Dill and colleagues compared weight-bearing and non-weight-bearing dorsiflexion measurements in the Journal of Athletic Training in 2014 and found they do not agree. They are two different readings. A degrees figure taken lying on a plinth does not convert into a centimetres figure taken standing against a wall, and neither replaces the other.
What the reading feeds
In Limber this test carries the calves and ankles area on its own — all of it, with nothing else feeding in.
That area is the whole of the Ankles group, and the Ankles group is the only one of the five groups the Range Score averages that a single test carries by itself. So this reading moves a fifth of your Range Score on its own, and a badly taken one moves it exactly as far. The Range Score prints the arithmetic rather than asking you to trust it.
One footnote on that fifth. The Spine group is fed only by a seated thoracic rotation test which is not built — not here and not in the app — so the ceiling today is four of the five stations, and this reading is one of the four that can be taken at all.
Pain that persists, wakes you at night, radiates into a limb, comes with numbness or weakness, or followed a fall or an injury is a matter for a clinician who can examine you. Add an ankle that gave way, an ankle you cannot put weight through, and a calf that is swollen, hot or noticeably larger than the other. Nothing here diagnoses anything and nothing here is treatment.
Take it, then take it again
One reading is a number. Two readings, three weeks apart, in the same conditions, are information.
Same hour, same warm-up or none, same footwear or none, tape anchored the same way, both sides in the same session. Write the date next to each number. Limber's default re-test interval is 21 days and it calls a reading older than that stale; the same clock works on paper.
Then read the number rather than ranking it. Ankle dorsiflexion explained covers what the movement is and what a low reading actually predicts. Ankle mobility drills covers the work, and grades how well it is supported — less well than the internet suggests. The rest of the cluster sits under hips and legs.
Questions
What is a normal knee to wall measurement?
Published figures for healthy adults usually cluster somewhere around 9 to 11 cm, but they move with how the test is set up — where the tape is anchored, whether shoes are worn, how hard the knee is driven forward — so a single published average is a weaker guide than it looks. On Limber's scale 6 cm reads 55 and 10 cm reads 85. The scale exists so the distance between two of your own readings means something, not so you can rank yourself against a group.
Does my heel have to stay down?
Yes, and it is the single thing that decides whether the reading repeats. The moment the heel lifts you are measuring a different movement, and the number can gain several centimetres with no change in the ankle. Keep the heel flat, the foot square to the wall and the knee tracking over the second toe, and take it the same way every time.
Why do 0, 1 and 2 cm all score the same?
Because the scale is flat below its first anchor. Under 2 cm the knee is barely clearing the toe and the test has stopped separating readings, so a scale that kept descending there would be adding precision the measurement does not have. The same holds above 12 cm, where everything reads 95. The app clamps at both ends, and this page shows the clamp rather than hiding it.
How big a difference between my ankles matters?
Limber flags 12 points or more, which on this test is roughly one and a quarter centimetres through the steep middle of the scale and about two and a half at the top. Below that, treat a difference as unmeasured rather than absent, because the published error on the test is a centimetre or two by itself. A gap worth acting on survives a second measuring session on a different day.
Can I use degrees from a physiotherapist instead?
Not interchangeably. Weight-bearing and non-weight-bearing dorsiflexion measurements do not agree, and the study that compared them found they behave as two different readings rather than two views of one. A goniometer figure taken lying down tells you something real. It does not convert into a centimetres figure taken standing against a wall, and mixing the two across sessions will show you a change that is not a change.
How often should I retake it?
Not daily. Range drifts with warmth and the hour, so day-to-day differences are mostly noise, and the test's own error swallows anything under a centimetre. Limber's default re-test interval is 21 days, adjustable to 14 or 28, and three weeks is a sensible clock on paper too. Write the number down with the date, and take both sides.