Health calculators

Frax Calculator

Updated Sep 5, 2026 By Infinity Calculator
Rate Formulas Sources Medical disclaimer
0
fracture risk assessments completed since June 1, 2011

Step 1: Region

Step 2: Demographics

Unit system
Age entry mode
Sex
Typical clinical range: 35–200 kg.
Calculated BMI: 23.9 kg/m²

Step 3: Clinical Risk Factors

Step 4: Bone Density (Optional)

Bone Mineral Density (BMD) — Optional. Adding BMD improves calculation accuracy. Leave blank to use clinical risk factors only. Anatomical site: Femoral Neck

BMD input mode
T-scores usually fall between −5.0 and +3.0.

Your 10-Year Fracture Risk

10-Year Probability of Hip Fracture
6.2%
High Risk
0%▏ 3% treatment threshold30%
10-Year Probability of Major Osteoporotic Fracture
16.9%
(Clinical spine, forearm, hip, or shoulder fracture)
Moderate Risk
0%▏ 20% treatment threshold40%

Population Comparison

Major Fracture — Site Breakdown
Your Risk vs. Intervention Threshold
Your Inputs (click to expand)
Step-by-Step Solution

Introduction

The FRAX Calculator estimates your chance of breaking a bone in the next 10 years. FRAX was developed by the WHO Collaborating Centre for Metabolic Bone Diseases at the University of Sheffield to help doctors decide who needs treatment for weak bones, also known as osteoporosis; this page is a simplified approximation of its models, not the FRAX tool itself. This tool looks at your age, sex, weight, height, and seven key risk factors (like past fractures, smoking, and steroid use) to give you two scores: your 10-year risk of a hip fracture and your 10-year risk of a major osteoporotic fracture (hip, spine, forearm, or shoulder).

You can also add a bone density measurement from a DXA scan if you have one. This makes the results more accurate, but it is not required. The calculator works without it by using your body mass index (BMI) instead.

Your results include a risk level (low, moderate, or high) based on widely used treatment thresholds. The Bone Health and Osteoporosis Foundation's clinician's guide recommends treatment when a FRAX 10-year hip fracture risk is 3% or higher or a major osteoporotic fracture risk is 20% or higher.2 Use these results to start a conversation with your doctor about bone health and next steps.

How to Use Our FRAX Fracture Risk Calculator

Enter your basic health details and risk factors below. The calculator will give you your 10-year chance of a hip fracture and a major osteoporotic fracture.

Country: Pick the country where you live. This sets the fracture risk model for your region.

Unit System: Choose metric (kg and cm) or imperial (lbs and ft-in) for your weight and height.

Age: Enter your age in years or switch to date of birth mode and type in your birthday. The tool works for ages 40 to 90.

Sex: Select female or male. This refers to your biological sex at birth.

Weight: Enter your body weight. The tool uses this to calculate your BMI.

Height: Enter your height. If you chose imperial, fill in both the feet and inches fields.

Previous Fracture: Select "Yes" if you have ever broken a bone as an adult from a minor fall or less.

Parent Hip Fracture: Select "Yes" if either of your biological parents broke a hip.

Current Smoking: Select "Yes" if you smoke tobacco right now in any form.

Glucocorticoid Use: Select "Yes" if you take oral steroids such as prednisolone at 5 mg or more per day for 3 months or longer.

Rheumatoid Arthritis: Select "Yes" if a doctor has confirmed you have rheumatoid arthritis.

Secondary Osteoporosis: Select "Yes" if you have a condition strongly tied to bone loss, such as type 1 diabetes, untreated hyperthyroidism, or early menopause.

Alcohol (3+ Units/Day): Select "Yes" if you drink 3 or more units of alcohol each day. One unit is about one beer, one small glass of wine, or one shot of spirits.

Bone Density (Optional): If you have had a DXA scan, choose T-score or BMD (g/cm²) mode and enter your femoral neck value. Leave this blank if you have not had a scan. Adding bone density makes the result more accurate. A T-score is a type of standard deviation measure.

Press Calculate Risk to see your results. You will get your 10-year hip fracture risk, your 10-year major osteoporotic fracture risk, a risk band (low, moderate, or high), a comparison to population averages, and a step-by-step breakdown of the math.

What Is the FRAX Fracture Risk Calculator?

FRAX stands for Fracture Risk Assessment Tool. It was created by the WHO Collaborating Centre at the University of Sheffield to help doctors figure out how likely a person is to break a bone in the next 10 years. Its models give the ten-year probability of hip fracture and of a major osteoporotic fracture (clinical spine, forearm, hip or shoulder), with and without bone density.1

Who Should Use This Tool?

FRAX is validated for adults between the ages of 40 and 90.2 It is most often used for people who may have weak bones but have not yet been treated for osteoporosis. Doctors, nurses, and patients can all use this tool to start a conversation about bone health.

How Does FRAX Work?

The calculator looks at several things that raise your chance of breaking a bone. These include your age, sex, weight, height, and country. It also asks about seven clinical risk factors:

  • Previous fracture: Have you broken a bone as an adult from a minor fall or less?
  • Parent hip fracture: Did either of your biological parents break a hip?
  • Current smoking: Do you smoke tobacco right now?
  • Glucocorticoid use: Have you taken oral steroid pills (like prednisone) for 3 months or more?
  • Rheumatoid arthritis: Has a doctor told you that you have this joint disease?
  • Secondary osteoporosis: Do you have a condition strongly linked to bone loss, such as type 1 diabetes or untreated thyroid disease?
  • Alcohol (3+ units per day): Do you drink 3 or more alcoholic drinks each day?

You can also enter a bone density (BMD) score from a DXA scan of the femoral neck. This is the narrow part of your thigh bone near the hip joint. Adding this score makes the result more accurate, but the calculator still works without it. When no BMD is available, the tool uses your BMI as a proxy for bone density. The seven clinical risk factors are the ones in the original FRAX models, alongside age, sex and BMI as a continuous variable.1

Understanding Your Results

After you fill in your information, the tool gives you two numbers. Each is a percentage chance of breaking a bone in the next 10 years.

  • Hip fracture risk: A result of 3% or higher is generally considered the point where treatment should be discussed.
  • Major osteoporotic fracture risk: A result of 20% or higher is the common treatment threshold in many guidelines.

These thresholds come from the Bone Health and Osteoporosis Foundation's clinician's guide for the United States.2 Other countries may use different cutoff numbers. Your doctor can tell you which threshold applies to you.

Bone health is just one part of your overall wellness picture. Maintaining a healthy caloric intake and monitoring calcium levels also play an important role in keeping bones strong.

Important Limitations

This calculator gives an estimate, not a diagnosis. It does not replace a visit with your doctor. FRAX does not account for dose effects. For example, it treats all steroid use the same whether the dose is low or high. It also does not include fall history or lumbar spine BMD. Fall risk can be influenced by balance and functional ability, which clinicians sometimes evaluate with the Berg Balance Calculator or the Tinetti Calculator. Always share your results with a healthcare provider so they can give you advice based on your full medical history.

Formulas used

Body Mass Index (BMI)
\text{BMI} = \frac{W_{\text{kg}}}{\left(\frac{H_{\text{cm}}}{100}\right)^{2}}
Femoral Neck T-score from BMD
T = \frac{\text{BMD} - 0.858}{0.120}
BMI Adjustment (when BMD not available)
\text{adj}_{\text{hip}} = e^{-0.08\,(\text{BMI}-25)}, \quad \text{adj}_{\text{MOF}} = e^{-0.03\,(\text{BMI}-25)}
BMD T-score Adjustment (when BMD available)
\text{adj}_{\text{hip}} = 2^{-T}, \quad \text{adj}_{\text{MOF}} = 1.5^{-T}
Baseline Cumulative Hazard
H_{0} = -\ln\!\left(1 - \frac{P_{\text{base}} \times f_{\text{region}}}{100}\right)
10-Year Fracture Probability
P = \left(1 - e^{-\,H_{0}\;\times\;\prod RR_{i}\;\times\;\text{adj}}\right) \times 100\%

Frequently asked questions

What does FRAX stand for?

FRAX stands for Fracture Risk Assessment Tool. It was made by the WHO Collaborating Centre at the University of Sheffield to predict the chance of breaking a bone in the next 10 years.

What is a T-score?

A T-score compares your bone density to that of a healthy 30-year-old adult. A T-score of 0 means your bones are average. A score of −1.0 to −2.5 means low bone mass (osteopenia). A score of −2.5 or lower means osteoporosis.

What is a major osteoporotic fracture?

A major osteoporotic fracture is a break at one of four sites: the hip, spine, forearm, or shoulder. These are the bones most likely to break due to weak bones from osteoporosis.

What do the risk levels low, moderate, and high mean?

Low risk means your chance of fracture is small. Moderate risk means your doctor may want to watch your bone health more closely. High risk means treatment, such as medication or lifestyle changes, should be discussed with your doctor.

Does sex affect fracture risk?

Yes. Women are at higher risk of fractures than men, especially after menopause. Estrogen helps keep bones strong, and estrogen levels drop significantly after menopause. The calculator uses biological sex at birth to set the correct baseline risk.

What counts as a previous fracture?

A previous fracture is any bone you broke as an adult from a minor fall or less. This includes breaks that happened without a major accident. Fractures from car crashes or other high-force events do not count.

Why does glucocorticoid use raise fracture risk so much?

Glucocorticoids (steroids like prednisone) weaken bones by slowing down the cells that build new bone and speeding up the cells that break bone down. Long-term use at doses of 5 mg or more per day is one of the strongest risk factors for fractures.

What is secondary osteoporosis?

Secondary osteoporosis means your bone loss is caused by another medical condition. Examples include type 1 diabetes, untreated hyperthyroidism, early menopause, chronic liver disease, and malabsorption disorders like celiac disease.

How much alcohol is 3 units per day?

One unit of alcohol is about 10 grams of pure alcohol. That equals roughly one standard beer, one small glass of wine, or one shot of spirits. Three units per day means three of any of these drinks daily.

What is the femoral neck and why is it measured?

The femoral neck is the narrow part of your thigh bone just below the ball of the hip joint. It is the standard site used in FRAX because hip fractures are the most serious type of osteoporotic fracture, and this area predicts hip fracture risk best.

Can I use lumbar spine BMD instead of femoral neck?

No. The FRAX model was designed to use femoral neck BMD only. Lumbar spine measurements are useful for diagnosis, but they are not validated for use in this calculator.

What if my BMD is entered in g/cm² instead of a T-score?

The calculator can accept either format. Switch to the BMD (g/cm²) input mode and enter your value. The tool will convert it to a T-score automatically using standard reference values. Those come from the NHANES III femoral-neck data for young white women published by Looker and colleagues; the exact mean and standard deviation are in that paper's tables.3

How is BMI used when I do not enter bone density?

When no BMD is provided, the calculator uses your body mass index (BMI) as a stand-in. A lower BMI is linked to thinner bones and higher fracture risk. A higher BMI generally means more weight on the bones, which can be somewhat protective. This is less accurate than a real bone density measurement.

Why does rheumatoid arthritis increase fracture risk?

Rheumatoid arthritis causes chronic inflammation that speeds up bone loss. Many people with this disease also take glucocorticoids, which weaken bones further. The disease itself also reduces mobility, which can lead to more falls.

What should I do if my result shows high risk?

Share your results with your doctor. They may recommend a DXA scan if you have not had one, medications to strengthen your bones, calcium and vitamin D supplements, weight-bearing exercise, and fall prevention strategies. Do not start any treatment on your own based on this calculator alone.

How often should I recalculate my FRAX score?

There is no set rule, but many doctors suggest rechecking every 2 to 5 years, or sooner if your health changes. For example, if you start taking steroids, break a bone, or get a new DXA scan, you should recalculate.

Does a parent's hip fracture have to be on a specific side of the family?

No. A hip fracture in either your mother or father counts. It does not matter which parent had the fracture. Only hip fractures are included. Other types of breaks in a parent do not apply here.

Does body weight alone protect against fractures?

Higher body weight puts more mechanical load on bones, which can make them stronger. However, being overweight does not eliminate fracture risk. Other factors like age, smoking, steroid use, and family history can still raise your risk significantly.

Sources

  1. Kanis JA, Johnell O, Oden A, Johansson H, McCloskey E. FRAX and the assessment of fracture probability in men and women from the UK. Osteoporosis International. 2008;19(4):385-397. doi:10.1007/s00198-007-0543-5. Accessed September 4, 2026.
  2. LeBoff MS, Greenspan SL, Insogna KL, Lewiecki EM, Saag KG, Singer AJ, Siris ES. The clinician's guide to prevention and treatment of osteoporosis. Osteoporosis International. 2022;33(10):2049-2102. doi:10.1007/s00198-021-05900-y. Accessed September 4, 2026.
  3. Looker AC, Wahner HW, Dunn WL, Calvo MS, Harris TB, Heyse SP, Johnston CC Jr, Lindsay R. Updated data on proximal femur bone mineral levels of US adults. Osteoporosis International. 1998;8(5):468-489. doi:10.1007/s001980050093. Accessed September 4, 2026.

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