How is the WOMAC score calculated?

In the Likert version each of the 24 items is scored 0–4 (none to extreme). Pain has 5 items (0–20), stiffness 2 (0–8) and physical function 17 (0–68). The total is the sum, 0–96; higher means worse symptoms and function. Example: pain 9, stiffness 4 and function 30 give a total of 43/96.

How do I convert a WOMAC score to 0–100?

Divide each raw score by its maximum and multiply by 100: pain ÷ 20, stiffness ÷ 8, function ÷ 68 and total ÷ 96 for the Likert version. A total of 43/96 is 44.8/100. Some studies reverse the scale (100 − score) so that 100 is best; always state the direction.

How are missing WOMAC items handled?

Statistical plans that follow the WOMAC user guide replace a missing item with the mean of the answered items in the same subscale, but treat the subscale as invalid when 2 or more pain items, both stiffness items, or 4 or more function items are missing. The total is invalid if any subscale is invalid.

What are the WOMAC NRS and VAS score ranges?

The NRS 3.1 version scores each item 0–10, so pain is 0–50, stiffness 0–20, function 0–170 and total 0–240. The VAS 3.1 version uses 0–100 mm lines: pain 0–500, stiffness 0–200, function 0–1700 and total 0–2400. Normalizing to 0–100 makes the versions comparable in direction, not interchangeable.

What change in WOMAC counts as a meaningful improvement?

The OMERACT-OARSI responder criteria (Pham et al., 2004) use 0–100 scores. A patient responds with either a high improvement in pain or function (at least 50% and at least 20 points) or improvement of at least 20% and 10 points in two of pain, function and patient global assessment. Published MCID values vary by study and setting.

Why are the 24 WOMAC questions not displayed here?

WOMAC is a licensed instrument. This page scores numbers taken from an authorized form, labelled P1–P5, S1–S2 and F1–F17, but does not reproduce the questionnaire wording. Licensing information is available from the WOMAC rights holder.

Does a WOMAC score diagnose osteoarthritis severity?

No. WOMAC is a patient-reported outcome measure, not a diagnosis, and there are no official severity bands. Interpret it alongside imaging, examination and change over time. This calculator is not medical advice.

WOMAC Score Calculator

Enter the 24 item scores (P1–P5, S1–S2, F1–F17) or the three subscale totals from an authorized WOMAC form. Likert totals run pain 0–20, stiffness 0–8, function 0–68 and total 0–96; the tool also handles NRS and VAS versions, missing items, 0–100 normalization and baseline-to-follow-up response.

Enter scores from an authorized WOMAC form

Version

Entry

Type each item score in form order. Leave unanswered items blank.

Pain (5 items)

Stiffness (2 items)

Physical function (17 items)

F10

F11

F12

F13

F14

F15

F16

F17

This calculator does not include the questionnaire. Obtain permission and the correct version at WOMAC.com. Not medical advice.

Scoring result

Enter item scores or the three subscale totals.

OMERACT-OARSI Responder Check

Enter 0–100 normalized scores (higher = worse) at baseline and follow-up. Patient global assessment (0–100, higher = worse) is optional. Criteria: Pham et al., Osteoarthritis Cartilage 2004.

Domain (0–100)	Baseline	Follow-up
WOMAC pain
WOMAC function
Patient global

Responder—

High improvement: pain or function improves by at least 50% and at least 20 points.

Otherwise, moderate improvement in two of three: pain, function and patient global each count when they improve by at least 20% and at least 10 points.

Worked example: pain 60 → 25 is a 35-point (58.3%) improvement, so the patient is a responder by the high-improvement rule regardless of function.

WOMAC Score Ranges by Version

Version	Item range	Pain (5)	Stiffness (2)	Function (17)	Total (24)
Likert 3.1	0–4	0–20	0–8	0–68	0–96
NRS 3.1	0–10	0–50	0–20	0–170	0–240
VAS 3.1	0–100 mm	0–500	0–200	0–1,700	0–2,400

Missing items (rules quoted in trial analysis plans that follow the WOMAC user guide): pain is invalid with 2 or more of 5 missing, stiffness with both missing, function with 4 or more of 17 missing; otherwise each missing item takes the mean of the answered items in its subscale. Any invalid subscale makes the total invalid.

Summary

This calculator scores the WOMAC osteoarthritis index from item responses or subscale totals for the Likert (0–4), NRS (0–10) and VAS (0–100 mm) versions. It applies the missing-item rules used with the WOMAC user guide, reports pain, stiffness, physical-function and total raw scores with a transparent 0–100 normalization, and checks baseline-to-follow-up change against the OMERACT-OARSI responder criteria. It does not reproduce the licensed questionnaire or invent severity bands, and it is not medical advice.

How it works

Choose the WOMAC version on your licensed form: Likert (items 0–4), NRS (0–10) or VAS (0–100 mm).
Enter each item score by its number (P1–P5, S1–S2, F1–F17), or switch to subscale totals if you already summed them.
Leave unanswered items blank; the user-guide rules impute or invalidate the subscale.
Calculate raw subscale and total scores plus the 0–100 normalized scores.
Optionally compare baseline and follow-up 0–100 scores against the OMERACT-OARSI responder criteria.

Use cases

Score a properly licensed WOMAC form item by item without re-adding by hand.
Apply the standard missing-item rules consistently across a dataset.
Convert Likert, NRS or VAS totals to a common 0–100 scale.
Check whether a patient meets the OMERACT-OARSI responder criteria between visits.
Document raw and normalized values together to avoid ambiguous reporting.

Frequently Asked Questions

Last updated: 2026-10-09 · Reviewed by Nham Vu