KOOS Score Calculator (0-100)
Enter each subscale's raw score (sum of item responses) and the number of items answered. Higher transformed KOOS scores indicate better knee status.
What is the KOOS?
The Knee injury and Osteoarthritis Outcome Score (KOOS) is a validated patient-reported outcome measure used in orthopedics, sports medicine, and rehabilitation. It captures how a person experiences their knee across five domains:
- Pain
- Symptoms (such as swelling, stiffness, and mechanical symptoms)
- Activities of Daily Living (ADL)
- Sport and Recreation
- Knee-related Quality of Life (QOL)
Clinicians and researchers often use KOOS after ACL injury, meniscus problems, cartilage issues, and knee osteoarthritis treatment to monitor progress over time.
How this KOOS calculator works
Each KOOS item is scored from 0 to 4. Raw totals are then transformed into a 0-100 scale where:
- 100 = no problems
- 0 = extreme problems
The formula used for each subscale is:
Transformed Score = 100 - (Raw Score × 100) / (4 × Number of Items Answered)
Important: This page provides a fast educational calculator and does not replace clinical judgment. Always interpret scores in context: diagnosis, exam findings, imaging, and change over time.
Step-by-step scoring guide
1) Add raw item scores for each KOOS domain
Use your completed KOOS questionnaire and sum the response values within each subscale.
2) Enter items answered
If all questions were answered, keep the default values (Pain 9, Symptoms 7, ADL 17, Sport/Rec 5, QOL 4). If any items are missing, reduce the item count accordingly.
3) Click calculate
The tool returns each transformed subscale score, an overall average of all five subscales, and KOOS4 (average of Pain, Symptoms, Sport/Rec, and QOL).
Interpreting your KOOS results
There is no single universal cutoff for every population, but this practical framework is commonly used for quick screening:
- 90-100: Excellent knee status, minimal symptoms
- 70-89: Mild limitations or intermittent symptoms
- 50-69: Moderate impact on function
- Below 50: Marked symptoms and functional impairment
For treatment decisions, trends matter more than one isolated number. A consistent upward trajectory across follow-up visits generally signals meaningful improvement.
Why KOOS is useful in real practice
- Patient-centered: Captures the patient's lived experience.
- Comprehensive: Includes daily function and sports demands, not just pain.
- Trackable: Easy to compare baseline to post-op or post-rehab results.
- Research-ready: Widely used in knee outcome studies.
Common mistakes to avoid
- Mixing raw totals and transformed scores in the same report.
- Forgetting that higher KOOS is better.
- Ignoring missing items when computing domain maxima.
- Using only one subscale and calling it "the KOOS score."
Frequently asked questions
Is KOOS the same as WOMAC?
Not exactly. KOOS extends WOMAC-style domains by adding Sport/Rec and QOL dimensions, making it more useful for active populations and post-injury tracking.
What is KOOS4?
KOOS4 is a summary average of four domains (Pain, Symptoms, Sport/Rec, QOL), excluding ADL. It is often used in ACL and sports-related outcome reporting.
Can I use this tool for clinical documentation?
Yes, as a quick calculator. But keep original questionnaire data and confirm your institution's scoring policy before final chart entry.