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Printed on 6/29/2026
For informational purposes only. This is not medical advice.
This fracture risk calculator provides a simplified estimate of 10-year probability for major osteoporotic fracture (spine, forearm, hip, or shoulder) and hip fracture alone, inspired by the WHO FRAX algorithm. It considers age, sex, BMI, previous fracture history, parental hip fracture, current smoking, glucocorticoid use, rheumatoid arthritis, and alcohol intake. Treatment thresholds: major osteoporotic fracture risk ≥20% or hip fracture risk ≥3% generally warrant pharmacologic treatment. Note: for official FRAX results including bone mineral density, use the WHO FRAX tool. Calculate BMI input with [BMI Calculator](/tools/bmi-calculator). For fall risk — the most important predictor of fracture — assess with [Timed Up and Go Test](/tools/get-up-and-go) and [Morse Fall Scale](/tools/morse-fall-scale). Assess overall frailty burden with [Clinical Frailty Scale](/tools/clinical-frailty). For patients on glucocorticoids, monitor glucose with [HbA1c Converter](/tools/hba1c-converter).
Formula: Simplified FRAX-inspired model. For official results use WHO FRAX (sheffield.ac.uk/FRAX).
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FRAX collects clinical risk factors that have been independently validated as predictors of osteoporotic fracture: Age (40–90 years): Fracture risk increases sharply with age due to declining bone density and increased fall frequency. Sex: Women have higher fracture risk at all ages due to hormonal bone loss at menopause. Weight/Height (for BMI): Low BMI (<19 kg/m²) is an independent risk factor for osteoporosis and fracture. Prior fragility fracture: Any fracture occurring with minimal trauma (fall from standing height or less) doubles the FRAX-predicted risk. Parental hip fracture: Family history of hip fracture is a significant independent risk factor for fracture, beyond what BMD captures. Current smoking: Associated with reduced bone formation and increased resorption. Glucocorticoids: Current oral glucocorticoid use (≥5 mg/day prednisolone for ≥3 months) significantly impairs bone formation. Rheumatoid arthritis: Independent risk factor beyond glucocorticoid use (disease-related bone loss). Secondary osteoporosis (type 1 diabetes, osteogenesis imperfecta, untreated hypogonadism, IBD, prolonged immobility, organ transplant). Alcohol ≥3 units/day: Impairs bone formation and increases fall risk.
FRAX can be calculated with or without bone mineral density (BMD). The tool is most accurate when femoral neck BMD T-score (from DXA scan) is incorporated. Adding BMD: Significantly improves fracture risk prediction accuracy (AUROC improves from ~0.65 without BMD to ~0.75 with BMD). Allows more precise treatment threshold decisions. The femoral neck T-score (not lumbar spine) is used in the official FRAX model. Without BMD: FRAX still provides useful risk stratification for patients who have not yet had a DXA scan. Can be used to decide whether DXA is indicated. May underestimate risk in patients with vertebral fractures (lumbar spine BMD is lower but femoral neck BMD may appear normal). If the patient has had a DXA scan, always incorporate the femoral neck BMD T-score. If using the official WHO FRAX tool, BMD can be entered as the femoral neck T-score or as the g/cm² measurement.
FRAX outputs two probabilities: (1) 10-year probability of major osteoporotic fracture (hip, spine, forearm, proximal humerus combined), and (2) 10-year probability of hip fracture alone. Apply treatment thresholds: US (NOF guidelines): Major fracture ≥20% OR hip fracture ≥3% = pharmacologic treatment generally recommended for patients with low bone mass (T-score -1.0 to -2.5). These thresholds apply to patients NOT already diagnosed with osteoporosis (T-score ≤-2.5) or with prior fragility fracture (those patients treat regardless of FRAX). UK (NOGG guidelines): Age-dependent thresholds (higher acceptable risk with increasing age). Country-specific thresholds vary — always confirm the appropriate threshold for your patient's country of origin. Treatment options for FRAX above threshold: bisphosphonates (alendronate, risedronate, zoledronate) as first-line; denosumab, teriparatide, or romosozumab for high-risk or bisphosphonate-intolerant patients.
Primary care physicians, internists, and endocrinologists
FRAX is specifically designed for the clinical scenario where a patient has osteopenia (DXA T-score -1.0 to -2.5) and the treatment decision is unclear. For patients with T-score ≤-2.5 (osteoporosis) or prior fragility fracture, treatment is indicated without FRAX. But for the large gray zone of osteopenia, FRAX provides the quantitative risk assessment needed for shared decision-making. Explain to patients: 'Your bone density scan shows low-normal bone density, not osteoporosis. Your 10-year fracture risk based on FRAX is 22% for a major fracture — above the 20% threshold where treatment is recommended.' This framing makes treatment recommendations data-driven and understandable.
Women's health specialists and gynecologists
Apply FRAX to post-menopausal women ≥50 with low bone density identified on screening DXA. USPSTF recommends DXA screening for all women ≥65 and younger post-menopausal women with risk factors. When DXA reveals osteopenia, FRAX risk stratifies further to identify who needs treatment vs lifestyle modification alone. FRAX also identifies high-risk women who should receive DXA more frequently (every 1–2 years vs every 5 years for low-risk). For women on long-term hormone therapy who discontinue at menopause, FRAX can quantify the accelerated bone loss risk and support early pharmacologic treatment.
Rheumatologists, pulmonologists, and gastroenterologists
Patients on long-term glucocorticoids (prednisone, prednisolone, methylprednisolone) are at high fracture risk due to rapid bone loss (3–5% in first year) and impaired bone repair. Apply FRAX to all patients starting glucocorticoid therapy ≥7.5 mg/day for ≥3 months. FRAX underestimates risk at high glucocorticoid doses (>7.5 mg/day prednisolone) — ACR guidelines recommend adjusting FRAX upward by 15% (multiply probability by 1.15) for very high-dose glucocorticoids. Guidelines recommend bisphosphonates for patients on chronic glucocorticoids with FRAX above threshold. Calcium (1200 mg/day) and vitamin D (800–1000 IU/day) are standard prophylaxis for all patients starting long-term steroids.
Primary care physicians and endocrinologists
Male osteoporosis is underdiagnosed and undertreated, partly because fracture risk is less prominent in teaching and less frequently recognized by both patients and physicians. FRAX applies to men aged 40–90 and is an important tool for identifying high-risk men who merit treatment. Key risk factors in men: hypogonadism (testosterone deficiency), chronic glucocorticoid use, excessive alcohol, prostate cancer with androgen deprivation therapy (ADT), and prior fragility fracture. Men on ADT (leuprolide, degarelix) have especially high fracture risk — FRAX combined with baseline DXA is essential in this population. Many guidelines recommend DXA and FRAX for men ≥70 or ≥50 with risk factors.
All clinicians managing osteoporosis
Use FRAX as part of the baseline assessment before initiating osteoporosis pharmacotherapy. Document: pre-treatment FRAX probability, DXA T-scores (lumbar spine and femoral neck), clinical risk factors present, and treatment threshold determination. This baseline allows meaningful monitoring — after 2–3 years of treatment, DXA should show stable or improving T-scores and FRAX risk should decrease. Note: FRAX should NOT be used to monitor treatment response (it is validated only for untreated patients). After starting bisphosphonates or other therapy, use DXA T-score progression and clinical fracture occurrence to monitor treatment efficacy.
Primary care providers in resource-limited settings
In settings where DXA access is limited (rural areas, developing countries, resource-constrained healthcare systems), FRAX without BMD can help prioritize which patients most urgently need DXA referral. A FRAX-without-BMD probability above the treatment threshold strongly supports urgent DXA referral and possibly empiric treatment while awaiting imaging. A very low FRAX probability without BMD (major fracture <5%, hip fracture <1%) suggests DXA can be deferred. The official WHO FRAX tool (frax.shef.ac.uk) provides country-specific calculations for 64 countries, making it globally applicable for DXA prioritization decisions.
The most important way to improve FRAX accuracy is to incorporate the femoral neck T-score from a DXA scan. FRAX without BMD underestimates fracture probability by approximately 20–30% in patients with significant bone loss, because clinical risk factors alone don't capture the full magnitude of bone density reduction. If the patient has had a DXA scan at any point (even years ago, if clinically relevant), enter the femoral neck T-score. Do not use lumbar spine T-score in FRAX — the tool is calibrated specifically for femoral neck BMD.
A prior fragility fracture (fracture from minimal trauma — standing height fall or less) is the most powerful clinical risk factor in FRAX and roughly doubles the 10-year fracture probability. Importantly, FRAX may still underestimate risk in patients with MULTIPLE prior fractures (it uses a dichotomous yes/no for prior fracture, not the number). For patients with 2 or more prior fragility fractures, clinical guidelines recommend treating even if FRAX is below the nominal threshold, because the absolute risk is clearly elevated. Always ask specifically: 'Have you ever broken a bone from a minor fall, twisting injury, or coughing?'
FRAX is calibrated using country-specific fracture incidence rates and mortality data. Using the wrong country model can significantly misestimate risk — for example, fracture rates differ substantially between Japan, Sweden, the US, and India. The official FRAX tool (frax.shef.ac.uk) provides models for 64 countries. Always select the patient's country of origin or residence. If the patient has recently immigrated, use clinical judgment — their fracture risk likely reflects their genetic/lifestyle background rather than the new country's epidemiology. Document which country model was used.
The FRAX model uses a dichotomous variable for glucocorticoid use (yes/no, ≥5 mg/day prednisolone for ≥3 months) and does not account for dose response. For patients on high-dose glucocorticoids (>7.5 mg/day prednisolone equivalent), fracture risk is substantially higher than FRAX calculates. ACR 2022 glucocorticoid-induced osteoporosis guidelines recommend multiplying the FRAX major fracture probability by 1.15 for high-dose users. For patients on very high doses (≥30 mg/day for prolonged periods), have a low threshold to start bisphosphonates regardless of FRAX, and obtain baseline DXA early in treatment.
Trabecular Bone Score (TBS) is a texture parameter derived from lumbar spine DXA that reflects bone microarchitecture independently of BMD T-score. TBS can be incorporated into FRAX (TBS-adjusted FRAX) to improve fracture risk prediction in patients where BMD alone underestimates risk — particularly in type 2 diabetes (BMD is paradoxically preserved but TBS is low), chronic kidney disease, rheumatoid arthritis, and primary hyperparathyroidism. If TBS is available from the DXA report, use TBS-adjusted FRAX for more accurate risk prediction in metabolic bone disease. Many DXA scanners now automatically provide TBS alongside standard BMD.
FRAX was developed and validated in untreated patients and is specifically designed as a treatment decision tool, NOT a monitoring tool. After initiating bisphosphonate or other osteoporosis therapy, FRAX should NOT be recalculated to assess treatment response, because the model assumptions no longer apply to treated patients. To monitor treatment efficacy: use serial DXA T-scores (repeat every 1–2 years during initial treatment, every 2–3 years if stable), assess for incident fractures, and monitor adherence. Some guidelines recommend stopping bisphosphonates after 5 years (drug holiday) — FRAX can then be recalculated in the drug-holiday period to assess continued treatment need.
Falls are the proximate cause of most hip and wrist fractures. FRAX estimates fracture probability from bone fragility perspective but does NOT incorporate fall risk assessment. A patient with high FRAX probability due to low BMD but with excellent balance and gait may have lower actual fracture risk than FRAX suggests. Conversely, a patient with low FRAX but very high fall risk (poor gait, polypharmacy, orthostatic hypotension, vision impairment) may fracture despite 'low' FRAX probability. Complement FRAX with fall risk assessment tools: Timed Up and Go (TUG) test, Morse Fall Scale, or comprehensive geriatric assessment. Fall prevention interventions (exercise, home hazard reduction, medication review) are as important as pharmacologic treatment.
FRAX does not include vitamin D status as a variable, but vitamin D deficiency independently contributes to fracture risk through reduced calcium absorption, increased bone resorption, and impaired muscle function (increasing fall risk). Before initiating bisphosphonate therapy, ensure vitamin D and calcium status is optimized — treating bisphosphonate-naive patients with severe vitamin D deficiency can cause severe hypocalcemia. Target vitamin D ≥30 ng/mL (75 nmol/L) for fracture prevention. All patients being treated for osteoporosis should receive calcium 1200 mg/day and vitamin D 800–1000 IU/day as adjuncts to pharmacotherapy.
FRAX was developed by Kanis et al. at the World Health Organization Collaborating Centre for Metabolic Bone Diseases, Sheffield, UK (Osteoporosis International 2008). Country-specific calibrations use nationwide fracture and mortality data. US treatment thresholds (major ≥20% or hip ≥3%) from the National Osteoporosis Foundation (NOF) Clinician's Guide 2014. FRAX validation studies confirm AUROC 0.65–0.73 for hip fracture. Limitations include: no dose-response for glucocorticoids, not validated for monitoring treatment.
Your estimated 10-year fracture risk is presented as two probabilities: one for any major osteoporotic fracture (hip, spine, forearm, or proximal humerus) and one for hip fracture alone. According to the National Osteoporosis Foundation (NOF) guidelines, pharmacologic treatment is generally recommended when the 10-year probability of a major osteoporotic fracture is 20% or greater, or when the 10-year probability of hip fracture is 3% or greater, in patients with low bone mass (T-score between -1.0 and -2.5).
A result below these thresholds does not mean fractures will not occur — it indicates that the absolute risk over 10 years is lower and that lifestyle interventions (calcium, vitamin D, weight-bearing exercise, fall prevention) may be sufficient. Your provider will integrate this result with bone mineral density testing and your overall clinical picture.
Use this tool for postmenopausal women and men aged 50 and older who have low bone mass (osteopenia, T-score between -1.0 and -2.5) but do not yet meet the diagnostic threshold for osteoporosis. It helps guide the decision about whether to initiate pharmacologic therapy with bisphosphonates or other osteoporosis medications.
FRAX is not needed when the decision to treat is already clear — for example, patients with a prior hip or vertebral fracture, or those with T-scores at or below -2.5, should generally receive treatment regardless of FRAX results. The tool is most valuable for borderline cases where the clinical benefit of treatment is uncertain.
This is a simplified approximation of the WHO FRAX algorithm and does not incorporate bone mineral density (BMD) measurements or country-specific fracture and mortality data. For official, validated results, the WHO FRAX tool at sheffield.ac.uk/FRAX should be used, particularly for clinical decision-making.
FRAX has several known limitations even in its official form. It uses dichotomous (yes/no) risk factors and does not account for dose-response relationships — for example, it does not differentiate between one and ten prior fractures, or between low-dose and high-dose glucocorticoid use. It also does not include fall history, which is a major independent risk factor for fractures. FRAX underestimates risk in patients with lumbar spine BMD significantly lower than femoral neck BMD, and it does not account for trabecular bone score or vertebral fractures found incidentally on imaging.
For related assessments, see Ottawa Ankle Rules, Ottawa Knee Rules and BMI Calculator.
Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.
April 21, 2026 · trust-baseline
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