Health calculators

Frax Calculator

Updated Nov 10, 2026 By Infinity Calculator Formulas Sources Medical disclaimer
Rate

Step 1: Demographics

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

Step 2: Clinical Risk Factors

Step 3: Bone Density (Optional)

Bone Mineral Density (BMD) is optional. Adding BMD improves calculation accuracy. Leave blank to use clinical risk factors and BMI 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
3.6%
At or above the threshold
0%▏ 3% treatment threshold30%
10-Year Probability of Major Osteoporotic Fracture
16.9%
(Clinical spine, forearm, hip, or shoulder fracture)
Below the threshold
0%▏ 20% treatment threshold40%

Population Comparison

Your Risk vs. Treatment 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 built from the FRAX figures published for the UK, 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 show whether each risk is below, or at or above, the US treatment threshold. The Bone Health and Osteoporosis Foundation's clinician's guide recommends considering treatment for postmenopausal women and men aged 50 and over who have low bone mass (osteopenia, a T-score between −1.0 and −2.5 at the femoral neck or total hip) when the US-adapted FRAX 10-year hip fracture risk is 3% or higher or the 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.

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. FRAX takes ages from 40 to 90. This calculator gives an estimate for ages 50 to 90 when you enter a bone density result, and for ages 50 to 80 without one. An age over 90 is counted as 90.

Sex: Select female or male.

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 now, or have taken them for more than 3 months at 5 mg or more of prednisolone a day (or an equivalent dose).

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, long-standing untreated hyperthyroidism, or premature menopause (before age 45).

Alcohol (3+ Units/Day): Select "Yes" if you drink 3 or more units of alcohol each day. One unit is 8 to 10 g of alcohol, about a 285 ml glass of beer, a 30 ml single measure of spirits, or a 120 ml glass of wine.

Bone Density (Optional): If you have had a DXA scan, choose T-score or BMD (g/cm²) mode and enter your femoral neck value. The clinician's guide recommends entering the BMD value rather than the T-score, because the T-score on a scan report may be based on a different reference group from the one FRAX uses.2 This calculator turns a BMD value into a T-score with the NHANES III reference for women aged 20 to 29, a mean of 0.858 g/cm² and a standard deviation of 0.120.3 The FRAX tool also asks which make of scanner measured the BMD, and this calculator does not. 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 to see your results. You will get your 10-year hip fracture risk, your 10-year major osteoporotic fracture risk, whether each risk is below, or at or above, the US treatment threshold, a comparison with the UK figure for someone of your age and sex with no risk factors, 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 and height. 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: Do you take oral steroid pills (like prednisone) now, or have you taken them for more than 3 months at 5 mg a day 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 long-standing untreated hyperthyroidism?
  • 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 part of your thigh bone just below the ball of 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 instead. 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: In the US guide, a result of 3% or higher in someone with low bone mass (osteopenia) is a point at which treatment is considered.2
  • Major osteoporotic fracture risk: In the same guide, a result of 20% or higher in someone with low bone mass is the other point at which treatment is considered.2

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. For everyone, the clinician's guide recommends enough calcium and vitamin D, not smoking, treating heavy drinking, and regular weight-bearing and muscle-strengthening exercise.2

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 3
T = \frac{\text{BMD} - 0.858}{0.120}
BMI Adjustment (when BMD not available)
\text{adj}_{\text{hip}} = \frac{-\ln\!\left(1 - P_{\text{hip}}(\text{BMI})/100\right)}{-\ln\!\left(1 - 1.3/100\right)},\ \ P_{\text{hip}}(20)=2.3\%,\ P_{\text{hip}}(25)=1.3\%,\ P_{\text{hip}}(40)=0.6\%, \quad \text{adj}_{\text{MOF}} = \min\!\left(\max\!\left(e^{-0.03\,(\text{BMI}-25)},\, 0.70\right),\, 1.60\right)
Baseline With Bone Density (when BMD available) 1
P_{\text{base}} = P_{\text{UK}}(\text{age},\ \text{sex},\ T), \quad \text{adj}_{\text{hip}} = \text{adj}_{\text{MOF}} = 1
Baseline Hazard and Risk-Factor Ratios 1
H_{0} = -\ln\!\left(1 - \frac{P_{\text{base}}}{100}\right), \quad RR_{i} = \frac{-\ln\!\left(1 - P_{i}/100\right)}{-\ln\!\left(1 - P_{\text{none}}/100\right)}
10-Year Fracture Probability
P_{\text{hip}} = \min\!\left(\left(1 - e^{-\,H_{0}\;\times\;\prod RR_{i}\;\times\;\text{adj}}\right) \times 100\%,\; 75\%\right), \quad P_{\text{MOF}} = \min\!\left(\left(1 - e^{-\,H_{0}\;\times\;\prod RR_{i}\;\times\;\text{adj}}\right) \times 100\%,\; 85\%\right)

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 with a young-adult reference group.2 FRAX works out T-scores from a reference group of white women aged 20 to 29.1 A T-score of 0 means your bone density equals the average of that young-adult group, not the average for your age. 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. In postmenopausal women and men aged 50 and over, a hip, spine or forearm fracture is consistent with osteoporosis unless tests show another cause.2

What does "at or above the threshold" mean?

Each result is marked as below, or at or above, the US treatment threshold: 3% for a hip fracture and 20% for a major osteoporotic fracture.2 These thresholds are for postmenopausal women and men aged 50 and over whose T-score at the femoral neck or total hip is between −1.0 and −2.5.2 A result at or above a threshold is a reason to talk with your doctor about treatment, not a diagnosis.

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 separate figures for women and men.

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, long-standing untreated hyperthyroidism, premature menopause (before age 45), chronic liver disease, and malabsorption disorders like celiac disease.

How much alcohol is 3 units per day?

FRAX counts one unit of alcohol as 8 to 10 grams of pure alcohol, about a 285 ml glass of beer, a 30 ml single measure of spirits, or a 120 ml glass of wine. 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 part of your thigh bone just below the ball of the hip joint. It is the site FRAX prefers for bone density.2

Can I use lumbar spine BMD instead of femoral neck?

No. FRAX can use femoral neck or total hip BMD, with the femoral neck preferred, and BMD from other sites is not recommended.2 Lumbar spine measurements are useful for diagnosis, but they are not validated for use in this calculator.

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 long-lasting inflammation in the joints. Having it raises the risk of osteoporosis, especially for people who take corticosteroids. The FRAX developers found that it raises fracture risk beyond what bone density alone explains.1

What should I do if my result is at or above the threshold?

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?

The 2019 Endocrine Society guideline advises reassessing fracture risk every 2 to 4 years for postmenopausal women with no previous spine or hip fracture, a T-score above −2.5 and a FRAX result below the treatment thresholds.2 Recheck 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?

A higher BMI goes with a lower risk. In the UK FRAX figures, a 65-year-old woman with no other risk factors had a 10-year hip fracture risk of 2.3% at a BMI of 20 and 0.6% at a BMI of 40.1 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. Fujiwara S, Nakamura T, Orimo H, Hosoi T, Gorai I, Oden A, Johansson H, Kanis JA. Development and application of a Japanese model of the WHO fracture risk assessment tool (FRAX™). Osteoporosis International. 2008;19:429-435. doi:10.1007/s00198-007-0544-4. Accessed November 10, 2026.

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