Health calculators

BASDAI Calculator

Updated Jul 7, 2026 By Jehan Wadia
Rate Formulas Medical disclaimer
Please answer each question based on how you have felt over the last 7 days.
6 of 6 questions answered 100%
Symptom Assessment
None5Very Severe
None6Very Severe
None3Very Severe
None4Very Severe
None6Very Severe
0 hours1 hour2 or more hours
5 — 1 hour

Your BASDAI Result

Score & Severity
Your BASDAI Score is: 4.70 out of 10
Moderate Disease Activity

Possible score range: 0.00 (minimum) – 10.00 (maximum)

Interpretation (ACR 2024 thresholds)
BASDAI ScoreDisease Activity Category
< 2.0Remission
2.0 – < 4.0Low Disease Activity
4.0 – < 6.0Moderate Disease Activity
≥ 6.0High Disease Activity
A BASDAI score of ≥ 4.0 is generally considered to indicate active disease that may warrant a treatment review. Results are a patient-reported measure and should be interpreted alongside a full clinical assessment.
Score Visualization
Step-by-Step Solution
Answer Review
QuestionYour Response
This note stays in your browser and appears only in the printout or downloaded file.

Introduction

The BASDAI Calculator (Bath Ankylosing Spondylitis Disease Activity Index) is a simple tool that measures how active your ankylosing spondylitis (AS) is. AS is a type of arthritis that mainly affects the spine, causing pain and stiffness. Doctors use the BASDAI score to see how severe your symptoms are and to help decide if your treatment plan needs to change.

The BASDAI asks six questions about how you have felt over the last seven days. These questions cover fatigue, spinal pain, joint pain, tenderness, and morning stiffness. You rate each answer on a scale from 0 to 10. The tool then combines your answers into a single score between 0 and 10. A score of 4 or higher usually means your disease is active and may need stronger treatment.

This calculator gives you a clear score, a step-by-step breakdown of the math, a color-coded severity gauge, and a printable report you can bring to your doctor. It is meant for adults who have been diagnosed with axial spondyloarthritis or ankylosing spondylitis. Your results are not a diagnosis — always share them with a qualified rheumatologist or healthcare provider who can review them alongside a full clinical exam, which may include related measures like your BMI and other health metrics.

How to Use Our BASDAI Calculator

This calculator asks you to rate six symptoms from the past week on a scale of 0 to 10. It then gives you a BASDAI score between 0 and 10 that shows how active your ankylosing spondylitis (AS) is.

Question 1 — Fatigue: Move the slider to rate your overall level of tiredness over the last 7 days. A 0 means no fatigue, and a 10 means the worst fatigue possible. Because poor sleep often worsens AS-related fatigue, you may also find our Sleep Calculator helpful for optimizing your rest.

Question 2 — Neck, Back, or Hip Pain: Move the slider to rate your overall AS-related pain in your neck, back, or hips. A 0 means no pain, and a 10 means the most severe pain.

Question 3 — Other Joint Pain or Swelling: Move the slider to rate pain or swelling in joints other than your neck, back, or hips. This includes joints like your knees, shoulders, or ankles.

Question 4 — Tenderness to Touch or Pressure: Move the slider to rate discomfort you feel when certain areas of your body are touched or pressed.

Question 5 — Morning Stiffness Level: Move the slider to rate how bad your morning stiffness feels when you first wake up. A 0 means no stiffness, and a 10 means the worst stiffness possible.

Question 6 — Morning Stiffness Duration: Move the slider to show how long your morning stiffness lasts after you wake up. A 0 means no stiffness at all, a 5 equals about 1 hour, and a 10 means 2 hours or more.

Once all six questions are answered, press the Calculate BASDAI Score button. The tool will display your score, a severity category, a color-coded gauge, step-by-step math, and charts you can print or download.

What Is the BASDAI Score?

The BASDAI stands for Bath Ankylosing Spondylitis Disease Activity Index. It is a simple test that measures how active your ankylosing spondylitis (AS) is. AS is a type of arthritis that mainly affects the spine, causing pain and stiffness in the back, neck, and hips. The BASDAI score helps you and your doctor understand how much the disease is bothering you right now.

How the BASDAI Calculator Works

The BASDAI uses six questions that you answer on a scale of 0 to 10. These questions ask about five key symptoms you felt over the last seven days:

  • Fatigue — how tired you have been
  • Spinal pain — pain in your neck, back, or hips
  • Joint pain or swelling — in areas other than your spine
  • Tenderness — discomfort when areas of your body are touched or pressed
  • Morning stiffness — how bad it is and how long it lasts

The two morning stiffness questions (Q5 and Q6) are averaged together. That average is added to the other four scores, and the total is divided by five. This gives you a final score between 0 and 10.

What Your Score Means

A score below 4 usually means your disease activity is low or in remission. A score of 4 or higher is the widely accepted cutoff for active disease. Doctors often use this cutoff to decide if a treatment change is needed. Scores between 4 and 6 point to moderate activity, and scores above 6 suggest high disease activity.

Why the BASDAI Matters

The BASDAI is one of the most commonly used tools in rheumatology for tracking AS. Because it is based entirely on your own reported symptoms, it gives your doctor a clear picture of how you actually feel. Many treatment guidelines, including those from the American College of Rheumatology (ACR), use the BASDAI to help guide decisions about starting or changing biologic medicines. Similar patient-reported and clinical scoring tools, such as the Barthel Index for functional ability, play an important role across many areas of medicine.

Important Things to Keep in Mind

The BASDAI is not a diagnosis tool. It does not replace lab tests such as GFR for kidney function monitoring, imaging, or a doctor's exam. Your score can change from week to week depending on flares, stress, or treatment. Tracking your score over time gives you and your healthcare provider a better view of how well your treatment plan is working.

Managing AS also means staying on top of your broader health. Keeping an eye on markers like your body fat percentage, daily calorie needs, and waist-to-hip ratio can help you manage inflammation-related cardiovascular risk. Regular exercise is one of the best strategies for reducing stiffness and fatigue — tools like a VO2 Max Calculator or a Heart Rate Zone Calculator can help you exercise safely and effectively. Always discuss your BASDAI results with a qualified rheumatologist before making any changes to your care.

Formulas used

Sum of Questions 1–4
S = Q_1 + Q_2 + Q_3 + Q_4
Mean of Morning Stiffness (Questions 5 & 6)
M = \frac{Q_5 + Q_6}{2}
Total Before Final Division
T = S + M
BASDAI Score
\text{BASDAI} = \frac{T}{5} = \frac{Q_1 + Q_2 + Q_3 + Q_4 + \dfrac{Q_5 + Q_6}{2}}{5}

Frequently asked questions

What does BASDAI stand for?

BASDAI stands for Bath Ankylosing Spondylitis Disease Activity Index. It is a scoring system created to measure how active your ankylosing spondylitis (AS) symptoms are. The name comes from the city of Bath in England, where the tool was first developed.

What is a normal BASDAI score?

There is no true "normal" score since healthy people without AS would score near 0. For people with AS, a score below 2 is considered remission, and a score between 2 and 4 is considered low disease activity. Scores at or above 4 mean the disease is active.

How is the BASDAI score calculated?

The calculator adds your answers for questions 1 through 4. Then it averages questions 5 and 6 (the two morning stiffness questions). That average is added to the sum of questions 1–4. The total is then divided by 5. This gives a final score between 0 and 10.

What does a BASDAI score of 4 or higher mean?

A score of 4 or higher usually means your AS is active. Many doctors use this as the cutoff to consider changing your treatment. It does not mean your condition is dangerous right now, but it does suggest your current plan may not be controlling your symptoms well enough.

How often should I take the BASDAI test?

Most rheumatologists suggest taking it at each clinic visit, which is often every 3 to 6 months. You can also use it between visits to track flares. Taking it regularly helps you and your doctor see if your treatment is working over time.

Can I use this calculator if I have non-radiographic axial spondyloarthritis?

Yes. The BASDAI is used for the full spectrum of axial spondyloarthritis (axSpA), which includes both ankylosing spondylitis and non-radiographic axial spondyloarthritis. The questions measure symptoms that apply to both conditions.

What does the Unknown checkbox do?

If you check the Unknown box for a question, it tells the calculator you cannot provide an answer for that item. However, all six questions must be answered to get a valid BASDAI score. The calculator will show an error if any question is marked as unknown.

Why are there two questions about morning stiffness?

Question 5 measures how severe your morning stiffness feels. Question 6 measures how long it lasts. These two aspects are averaged together because both the intensity and the duration of stiffness are important signs of active inflammation in AS.

What time period should I think about when answering?

You should base every answer on how you have felt during the last 7 days. Do not think about months ago or just today. A full week gives a more accurate picture of your current disease activity.

Is the BASDAI the same as the BASFI?

No. The BASDAI measures disease activity — how much pain, stiffness, and fatigue you feel. The BASFI (Bath Ankylosing Spondylitis Functional Index) measures function — how well you can do daily tasks like bending, reaching, or standing. Doctors often use both together.

Does this tool save or send my data?

No. All calculations happen in your browser. Your answers and your score are not saved, stored, or sent to any server. If you close or refresh the page, your data is gone. Use the print or download button if you want to keep a copy.

Can I print or download my results?

Yes. After you calculate your score, you will see a Print Results button and a Download Result button. Print opens a printer-friendly page. Download saves an HTML file to your device. Both include your score, severity category, answer review, and any note you added.

What do the colors on the severity gauge mean?

The gauge uses four colors. Green (0–2) means remission. Teal (2–4) means low disease activity. Orange (4–6) means moderate disease activity. Red (6–10) means high disease activity. A black marker shows where your score falls.

Can my BASDAI score change from week to week?

Yes. Your score can go up during a flare and come back down when symptoms improve. Stress, illness, missed medication, or changes in activity can all affect your score. That is why tracking it over time is more useful than looking at a single result.

Is a BASDAI score of 0 possible?

Yes. A score of 0 means you reported no fatigue, no pain, no tenderness, and no morning stiffness at all over the past week. This is uncommon for someone with active AS, but it can happen during full remission or with very effective treatment.

Does the BASDAI score tell me my diagnosis?

No. The BASDAI only measures symptom severity in people who already have a diagnosis of AS or axial spondyloarthritis. It cannot diagnose AS. A diagnosis requires imaging, blood tests, a physical exam, and a doctor's assessment.

Should I share my BASDAI score with my doctor?

Yes. Bringing your score to your appointment gives your rheumatologist a quick snapshot of how you have been feeling. It can help guide treatment decisions, especially if your score is 4 or above and a change in therapy may be needed.

What is the difference between the bar, donut, and waffle charts?

All three charts show the same score in different ways. The bar chart shows your score on a horizontal bar with colored severity zones. The donut chart shows your score as a portion of 10. The waffle chart fills small squares to represent your score visually. Pick whichever one is easiest for you to read.

Can children use this calculator?

The BASDAI was designed for adults with ankylosing spondylitis or axial spondyloarthritis. It has not been validated for children. If a child has symptoms of juvenile spondyloarthritis, a pediatric rheumatologist should choose the right assessment tool.

What should I do if my score is above 4?

A score above 4 suggests your disease is active. You should bring this result to your rheumatologist. They may review your current medications, order lab tests, or adjust your treatment plan. Do not change your medication on your own based on this score alone.