FRAX Score Calculator
Estimate Your 10-Year Probability of an Osteoporotic Fracture
Risk Assessment Tool
Enter your age (between 40 and 90).
Select your biological sex.
Enter your weight in kilograms.
Enter your height in centimeters.
Clinical Risk Factors
Optional, but increases accuracy. Leave blank if not known.
What is a FRAX Score?
The Fracture Risk Assessment Tool, or FRAX, is a widely used algorithm that helps to calculate FRAX score, which represents a person’s 10-year probability of experiencing a major osteoporotic fracture. Developed by the World Health Organization (WHO), this tool is designed for healthcare professionals but can also be used by individuals to understand their fracture risk. The output is given as two percentages: the 10-year probability of a hip fracture, and the 10-year probability of a major osteoporotic fracture (which includes fractures of the clinical spine, forearm, hip, or shoulder).
Understanding your FRAX score is crucial for anyone over the age of 40, especially postmenopausal women and older men, who are at a higher risk for osteoporosis. Osteoporosis is a condition that weakens bones, making them brittle and more susceptible to breaking. A high FRAX score can be a prompt for a discussion with your doctor about bone health, diagnostic tests like a bone mineral density (BMD) scan, and potential lifestyle changes or treatments. This calculator helps to quantify that risk based on well-established risk factors.
FRAX Score Formula and Explanation
The official FRAX tool uses complex, population-specific statistical models derived from extensive cohort studies. This calculator uses a simplified, illustrative formula to demonstrate how different factors contribute to the overall risk. It is intended for educational purposes and is not a substitute for a professional medical assessment.
The calculation can be conceptualized as:
Risk Score = Base Risk(Age, Sex, BMI) + Sum(Risk Factor Weights) - (BMD * BMD_Weight)
The ‘Risk Score’ is then converted into a 10-year probability percentage. This shows how a lower Body Mass Index (BMI), older age, and the presence of various clinical risk factors each increase the final probability. Including a Bone Mineral Density (BMD) value significantly refines the result.
| Variable | Meaning | Unit / Type | Typical Range |
|---|---|---|---|
| Age | Patient’s current age | Years | 40 – 90 |
| Sex | Biological sex | Categorical (Male/Female) | N/A |
| BMI | Body Mass Index | kg/m² | 15 – 40 |
| Previous Fracture | A prior fracture as an adult | Yes / No | N/A |
| Parent Fractured Hip | Mother or father had a hip fracture | Yes / No | N/A |
| Smoking | Currently smokes cigarettes | Yes / No | N/A |
| Glucocorticoids | Currently taking oral steroid tablets | Yes / No | N/A |
| BMD | Femoral neck bone mineral density | g/cm² | 0.5 – 1.4 |
Practical Examples
Example 1: Lower-Risk Individual
Let’s consider a 55-year-old male who is 80kg and 180cm, does not smoke, has no other risk factors, and a healthy BMD of 1.1 g/cm². To calculate FRAX score for him:
- Inputs: Age=55, Sex=Male, Weight=80kg, Height=180cm, All risk factors=No, BMD=1.1.
- Intermediate Value (BMI): 24.7 kg/m².
- Results: The calculator would show a low 10-year probability for both major and hip fractures, reflecting his healthy profile.
Example 2: Higher-Risk Individual
Now, let’s analyze a 70-year-old female who is 55kg and 160cm. She is a current smoker, had a previous fracture, and her mother had a hip fracture. Her BMD is not known. To calculate FRAX score for her:
- Inputs: Age=70, Sex=Female, Weight=55kg, Height=160cm, Smoking=Yes, Previous Fracture=Yes, Parent Fracture=Yes.
- Intermediate Value (BMI): 21.5 kg/m².
- Results: Her score would be significantly elevated. The combination of advanced age, female sex, low BMI, and multiple strong risk factors results in a high 10-year fracture probability, indicating a need for clinical attention. For more information, you might want to read about Osteoporosis Risk Factors.
How to Use This FRAX Score Calculator
- Enter Personal Data: Start by entering your age, sex, weight (in kg), and height (in cm). The calculator will automatically compute your BMI.
- Select Risk Factors: Check the box for each clinical risk factor that applies to you. These include a personal history of fracture, a parental hip fracture, smoking status, and certain medical conditions or medications. Be honest for an accurate estimation.
- Enter BMD (Optional): If you have had a DXA scan and know your femoral neck Bone Mineral Density (BMD) in g/cm², enter it. This will greatly improve the accuracy of the risk calculation. If you don’t know it, simply leave the field blank.
- Review Your Results: The calculator instantly updates to show your 10-year probability of a major osteoporotic fracture and a hip fracture. A bar chart provides a visual comparison of these two values.
- Interpret the Score: The results section provides a brief explanation. Generally, a major osteoporotic fracture risk over 20% or a hip fracture risk over 3% is considered high and warrants discussion with a healthcare provider.
To learn more about what your results might mean, consider our guide on understanding bone density.
Key Factors That Affect FRAX Score
- Age: Fracture risk increases significantly with age.
- Sex: Women are more susceptible to osteoporosis and fractures than men, particularly after menopause.
- Body Mass Index (BMI): A low BMI (below 18.5) is a strong risk factor for fracture.
- Previous Fragility Fracture: A past fracture from a minor incident more than doubles the risk of a future one.
- Parental Hip Fracture: A family history of hip fracture indicates a genetic predisposition to weaker bones.
- Smoking: Tobacco use is directly toxic to bones and increases fracture risk.
- Glucocorticoid Use: Long-term use of oral steroids is a major cause of medication-induced osteoporosis.
- Alcohol Intake: Consuming three or more alcoholic drinks per day is associated with higher fracture risk.
For a complete overview of what influences bone health, see our article on The Complete Guide to Bone Health.
Frequently Asked Questions
No. This is an educational tool that provides an estimation based on a simplified model. The official FRAX tool should be used by a healthcare professional for clinical diagnosis and treatment decisions. Please consult your doctor for an accurate assessment.
Treatment is often recommended if your 10-year probability of a major osteoporotic fracture is ≥20% or the probability of a hip fracture is ≥3%. However, these thresholds can vary by country and clinical judgment.
A high score is not a diagnosis, but a call to action. You should schedule an appointment with your doctor to discuss your bone health. They may recommend a DXA scan to measure your bone mineral density (BMD) and suggest lifestyle changes or treatment. You can read about osteoporosis treatment options here.
Yes. While you can’t change factors like age or genetics, you can modify lifestyle risks. Quitting smoking, reducing alcohol intake, ensuring adequate calcium and vitamin D, and performing weight-bearing exercise can all help lower your risk.
FRAX was designed to be useful even without a BMD test, which may not be readily available to everyone. However, including a BMD result makes the calculate FRAX score process much more accurate.
The official FRAX models are calibrated for different countries and ethnicities. This simplified calculator does not adjust for race or ethnicity, which is a limitation. The risk can vary between different populations.
This refers to osteoporosis caused by another medical condition (like rheumatoid arthritis, hyperthyroidism, or chronic liver disease) or by certain medications. If you have such a condition, you should check this box.
This refers to a fragility fracture, meaning a fracture that occurred spontaneously or from a fall from a standing height or less, as an adult (age 40+). Fractures from major trauma, like a car accident, are not included.