What is a BASDAI score?

BASDAI (Bath Ankylosing Spondylitis Disease Activity Index) is a patient-reported measure of disease activity in axial spondyloarthritis and ankylosing spondylitis. Six symptom questions are combined into a single score from 0 to 10.

How do you calculate BASDAI?

Average morning stiffness severity and duration, add that to fatigue, spinal pain, peripheral joint pain and enthesitis discomfort, then divide by five. BASDAI = (Q1 + Q2 + Q3 + Q4 + ((Q5 + Q6) / 2)) / 5.

What is a good BASDAI score?

Lower scores generally mean less active symptoms. A score of 4 or above is often used in research as a threshold for active disease, but interpretation depends on your full clinical picture and treatment history.

Does Hurtl calculate BASDAI automatically?

Yes. Hurtl calculates a BASDAI estimate from your daily logs — fatigue, pain, stiffness and enthesitis — with a 7-day trend on the Condition tab. Log once a day and your score updates automatically.

How often should BASDAI be measured?

In clinic, BASDAI is often completed at appointments. For personal tracking, logging underlying symptoms regularly gives a more accurate picture than trying to recall how the past month felt from memory.

1 June 2026

BASDAI Calculator – Ankylosing Spondylitis Disease Activity

By Tom, founder of Hurtl.

Use the BASDAI calculator below to estimate your Bath Ankylosing Spondylitis Disease Activity Index score from six standard questions. You can also read how BASDAI is calculated and what your result means.

BASDAI calculator

Answer the six standard BASDAI questions for the past week (0 = no problem, 10 = worst imaginable). Morning stiffness severity and duration are averaged before the final calculation.

Your BASDAI score: 0.0 / 10

Lower disease activity

(Fatigue 0 + Spinal 0 + Peripheral 0 + Enthesitis 0 + Stiffness avg 0.0) ÷ 5 = 0.0

For education only — not a diagnosis. Scores here are estimates from the values you enter. Your clinician may calculate BASDAI differently at appointments. Hurtl’s in-app BASDAI estimate is built from daily logs and may differ from a single self-assessment.

All rheumatology calculators · axial spondyloarthritis tracker

What is BASDAI?

BASDAI stands for Bath Ankylosing Spondylitis Disease Activity Index. It was developed as a way to measure how active axSpA symptoms are, using questions patients answer about their recent experience.

Despite the name referencing ankylosing spondylitis, BASDAI is widely used across axial spondyloarthritis, including non-radiographic axSpA.

The six BASDAI questions

Each question is scored from 0 to 10, where 0 means no problem and 10 means the worst imaginable. You rate your experience over a recent period (commonly the past week):

Fatigue/tiredness overall
Spinal pain (neck, back or hips)
Joint pain/swelling in joints other than the spine
Discomfort from tender areas (enthesitis)
Morning stiffness severity when you wake up
Morning stiffness duration

Questions 5 and 6 both relate to morning stiffness and are averaged in the formula.

How BASDAI is calculated

BASDAI = (Q1 + Q2 + Q3 + Q4 + ((Q5 + Q6) / 2)) / 5

The result is a single score from 0 to 10.

Worked example

Question	Score
Fatigue (Q1)	6
Spinal pain (Q2)	5
Peripheral joint pain (Q3)	2
Enthesitis discomfort (Q4)	3
Morning stiffness severity (Q5)	7
Morning stiffness duration (Q6)	6

Stiffness average: (7 + 6) / 2 = 6.5 · BASDAI: (6 + 5 + 2 + 3 + 6.5) / 5 = 4.5

What do BASDAI scores mean?

Lower scores (closer to 0): generally less active symptoms
Scores of 4 or above: often considered to suggest active disease in research

A single score is a snapshot — trends matter more. This is not a diagnosis tool.

Tracking axial spondyloarthritis over time

Log fatigue, pain, stiffness and enthesitis consistently — Hurtl calculates a BASDAI estimate daily from your logs.

See our axial spondyloarthritis tracker, ankylosing spondylitis tracker, how to track ankylosing spondylitis symptoms, all rheumatology calculators, or why track symptoms between appointments.

This article explains BASDAI for general information only. It is not medical advice, a diagnosis, or a recommendation to start, stop, or change treatment. BASDAI scores should be interpreted by your rheumatologist in the context of your full clinical picture. Hurtl is not a medical device and does not provide clinical monitoring or treatment decisions.