Hurtl
What Is WOMAC and How Is It Calculated?
By Tom, founder of Hurtl.
If you live with osteoarthritis (OA), you may hear your clinician refer to WOMAC at appointments. It is one of the most widely used patient-reported measures in OA — a structured way to capture pain, stiffness and physical function in a single framework your care team can track over time.
What is WOMAC?
WOMAC stands for the Western Ontario and McMaster Universities Osteoarthritis Index. It was developed for hip and knee osteoarthritis and is now used more broadly when clinicians want a standardised view of how OA affects daily life.
Clinicians use WOMAC because it is:
- Patient-reported — you describe pain, stiffness and function from your own experience
- Focused on what matters day to day — walking, stairs, household tasks, morning stiffness
- Repeatable — the same domains can be compared visit to visit
WOMAC is not a diagnosis tool. It supports monitoring and treatment discussions alongside examination, imaging and your full clinical picture.
The three WOMAC domains
Full clinical WOMAC uses 24 questionnaire items grouped into three domains, usually scored 0 to 4 per item:
- Pain (5 items) — pain during walking, stairs, in bed, sitting or lying, and standing upright
- Stiffness (2 items) — stiffness after waking and later in the day
- Physical function (17 items) — difficulty with daily activities such as descending stairs, rising from sitting and household tasks
Clinicians sum or normalise these items for interpretation. Hurtl and the calculator below use simplified domain-level estimates (pain, stiffness, function) aligned with daily symptom tracking — not the full 24-item clinical questionnaire.
How WOMAC is calculated
In clinic, your clinician applies the standard WOMAC questionnaire and combines scores from all three domains. Totals depend on whether raw sums or normalised scores are used.
For daily tracking in Hurtl, a WOMAC estimate is calculated from pain, stiffness and physical function logged over time — with a 7-day trend on the Condition tab. This is an estimate from your entries, not an official clinical score.
Simplified domain estimate (for self-tracking)
When estimating from three domain scores on a 0 to 10 scale (as in the calculator below):
WOMAC estimate = Pain + Stiffness + Physical function
On this simplified scale, the total ranges from 0 to 30. Full clinical WOMAC uses more items and a different scoring range — your clinician’s version may not match a one-off self-assessment.
Worked example (simplified)
| Domain | Score |
|---|---|
| Pain | 5 |
| Stiffness | 4 |
| Physical function | 6 |
WOMAC estimate: 5 + 4 + 6 = 15
Try the calculator
Rate pain, stiffness and physical function below (0–10 each) to estimate a simplified WOMAC total.
WOMAC calculator
Estimate a simplified WOMAC-style total from three domains (pain, stiffness, physical function), each rated 0 to 10. Full clinical WOMAC uses 24 questionnaire items — Hurtl and this tool use domain-level estimates aligned with daily tracking.
Pain 0 + Stiffness 0 + Function 0 = 0
For education only — not a diagnosis. Scores here are estimates from the values you enter. Your clinician may calculate WOMAC differently at appointments. Hurtl’s in-app WOMAC estimate is built from daily logs and may differ from a single self-assessment.
What do WOMAC scores mean?
There is no universal “good” score for everyone. Interpretation depends on which joints are affected, your treatment and what your clinician is looking for.
As a general guide:
- Lower scores usually mean less pain, shorter stiffness and easier daily function
- Higher scores suggest more symptomatic OA affecting daily life
- Trend over time matters more than a single number — is function improving after physiotherapy, or pain creeping up before you adjust treatment?
These are not rules you should apply on your own to change treatment. Always discuss results with your care team.
Why memory makes clinic scores hard
WOMAC asks about symptoms over recent weeks, but many people answer from how they feel today. You might remember this morning’s stiffness clearly but forget that stairs were manageable most of last month — or the opposite. That recency bias can make clinic scores less accurate than your real experience.
How tracking supports WOMAC in practice
You do not need to calculate WOMAC manually every day. Log the underlying symptoms your clinician will ask about — Hurtl builds a running WOMAC estimate:
- Joint pain and which joints are affected
- Stiffness — severity and duration
- Function — how symptoms affect walking, stairs and daily tasks
- Flares and what may have triggered them
- Medication and treatment adherence
Hurtl calculates a WOMAC estimate daily from your logs on the Condition tab, with a 7-day trend. You can also export a clinical PDF report with symptom trends and medication adherence so appointments start from what you recorded, not memory.
See our osteoarthritis symptom tracker to get started, or read why track symptoms between appointments for habits that make any score more meaningful.