BASDAI Score Calculator (ankylosing spondylitis disease activity)

Understanding the BASDAI score calculator — concept and principle

This calculator works out the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) from six self-rated questions about the past week. It gives the score from 0 to 10, whether it reaches the commonly used activity threshold of 4, and the converted morning stiffness duration item. People with axial spondyloarthritis and their rheumatology teams use it to track disease activity.

Average of five symptom areas — with the default inputs: BASDAI 4.2.

How it is calculated

Questions 1–5 are rated 0 (none) to 10 (very severe): fatigue, spinal pain, other joint pain or swelling, tenderness, severity of morning stiffness
Question 6 converts stiffness duration: 0 hours = 0, 1 hour = 5, 2 hours or more = 10, proportionally in between
BASDAI = (Q1 + Q2 + Q3 + Q4 + (Q5 + Q6) ÷ 2) ÷ 5
A score of 4 or more is commonly used as a sign of active disease

The principle

Garrett and colleagues developed the BASDAI in 1994 so that people with ankylosing spondylitis could rate the main features of disease activity themselves. Averaging the two stiffness questions means stiffness counts as one of five equal parts. Because it is self-reported and quick, it can be repeated at each visit to show trends. The threshold of 4 appears in many treatment guidelines as one criterion for considering changes in therapy.

Worked example

Defaults: fatigue 5, spinal pain 6, other joints 2, tenderness 3, stiffness severity 5, stiffness duration 1 hour.

Duration item = 1 hour → 5.
Stiffness average = (5 + 5) ÷ 2 = 5.
BASDAI = (5 + 6 + 2 + 3 + 5) ÷ 5 = 4.2.
4.2 ≥ 4: Active (4 or more).

Each point is the calculator re-run with only “1. Fatigue or tiredness over the past week (0–10)” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

1. Fatigue or tiredness over the past week (0–10)	BASDAI score (0–10)
1.25	3.5
2.5	3.7
3.75	4
5	4.2
6.25	4.5
7.5	4.7
10	5.2

How to read the result

Where does your result fall?

A single score is most useful compared with your previous scores. A score of 4 or more suggests active disease, but treatment decisions also consider examination, blood tests, imaging and how you function day to day. Bring your scores to appointments.

Common mistakes

Rating the worst day instead of the past week overall.
Entering stiffness duration in minutes instead of hours.
Comparing scores from different questionnaire versions.
Treating the threshold as a diagnosis.

Keep in mind: Not a diagnosis. Discuss changes in your symptoms and treatment with your rheumatology team.

Frequently asked questions

What is a high BASDAI score?

4 or more is commonly used to indicate active disease.

How long does morning stiffness need to last to score 10?

2 hours or more.

How often should I complete the BASDAI?

As often as your care team suggests, often at each review.

Sources: Garrett S, Jenkinson T, Kennedy LG, Whitelock H, Gaisford P, Calin A, "A new approach to defining disease status in ankylosing spondylitis: the Bath Ankylosing Spondylitis Disease Activity Index", J Rheumatol 1994;21(12):2286–2291

Checked 9 Nov 2026. Garrett S, Jenkinson T, Kennedy LG, Whitelock H, Gaisford P, Calin A, “A new approach to defining disease status in ankylosing spondylitis: the Bath Ankylosing Spondylitis Disease Activity Index”, J Rheumatol 1994;21(12):2286–2291 (questions and formula as in QxMD Calculate “BASDAI”; cut-off of 4 as in RheumInfo “BASDAI”).

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