What T-score range is osteopenia?

Osteopenia (low bone mass) is a T-score below -1.0 but above -2.5, which on a one-decimal DXA report means -1.1 through -2.4. A T-score of exactly -1.0 is still normal, and exactly -2.5 is in the osteoporosis range.

Which T-score counts if my spine and hip are different?

ISCD uses the lowest T-score of the lumbar spine (L1–L4), total hip and femoral neck. If your spine is -1.4 and femoral neck -2.6, the result is osteoporosis. The 33% radius counts only when the hip or spine cannot be measured or interpreted, in hyperparathyroidism, or when the patient exceeds the table weight limit.

How do I convert BMD in g/cm² to a T-score?

T-score = (your BMD − young-adult mean BMD) ÷ young-adult SD. For the femoral neck, the NHANES III young white women reference is 0.858 ± 0.120 g/cm², so a BMD of 0.650 gives (0.650 − 0.858) ÷ 0.120 = -1.73. Scanner makers use their own spine references, so use the mean and SD on your report.

What is the difference between a T-score and a Z-score?

A T-score compares your bone density with a healthy young adult; a Z-score compares it with people of your age and sex. T-scores diagnose osteoporosis in postmenopausal women and men 50+. Z-scores are used for premenopausal women, men under 50 and children, where -2.0 or lower is "below the expected range for age".

Is there a bone density T-score chart by age?

No. The WHO T-score cutoffs (-1.0 and -2.5) are the same at every age because a T-score always compares with a young-adult reference. Comparison with people of the same age and sex is a Z-score.

What is severe or established osteoporosis?

The WHO defines severe (established) osteoporosis as a T-score of -2.5 or lower plus one or more fragility fractures. Guidelines such as BHOF also diagnose osteoporosis clinically after a hip or vertebral fragility fracture, even when the T-score is above -2.5.

Does a low T-score automatically mean high fracture risk?

No. Fracture risk also depends on age, prior fracture, glucocorticoids, parental hip fracture, smoking, alcohol and other factors, which FRAX combines. In the US, treatment is commonly considered for low bone mass when the FRAX 10-year risk is at least 3% for hip fracture or 20% for a major osteoporotic fracture.

Is this calculator medical advice?

No. It categorizes numbers for education. Diagnosis and treatment decisions need a clinician who reviews the full DXA report, scan quality, history and fracture risk.

Bone Density T-Score Calculator

Enter DXA T-scores (or Z-scores if under 50) for each scanned site; the lowest of spine, total hip and femoral neck sets the WHO category. A second tool converts BMD in g/cm² to a T-score using NHANES III or your report's reference.

The WHO T-score chart classifies a DXA T-score of -1.0 or higher as normal, between -1.0 and -2.5 as low bone mass (osteopenia), and -2.5 or lower as osteoporosis.

Enter Your DXA Scores

Copy the scores from your DXA report. Fill in every site that was measured; ISCD uses the lowest of lumbar spine, total hip and femoral neck.

Population group *

T-scores by site (SD)

Lumbar spine (L1–L4)

Total hip

Femoral neck

33% radius

33% radius counts only when the hip or spine cannot be measured or interpreted, in hyperparathyroidism, or above the table weight limit (ISCD). Leave blank sites empty.

Prior low-trauma (fragility) fracture, e.g. hip, spine or wrist from a standing-height fall

WHO T-Score Categories (age 50+)

Category	T-score
Normal bone density	≥ −1.0
Low bone mass (osteopenia)	−1.1 to −2.4 (−2.5 < T < −1.0)
Osteoporosis	≤ −2.5
Severe (established) osteoporosis	≤ −2.5 + fragility fracture

ISCD Z-Score Wording (under 50)

Within the expected range for age	> −2.0
Below the expected range for age	≤ −2.0

Definitions & Diagnostic Scope

T-score: (your BMD − young-adult mean) ÷ young-adult SD. ISCD recommends the NHANES III white-female reference for hip T-scores in women and men of all ethnic groups.
Z-score: the same calculation against people of your age and sex; it does not diagnose osteoporosis.
Privacy: Scores are interpreted locally in your browser and masked from session-replay capture.
Not medical advice: educational categorization only; a clinician interprets the full DXA report.

Ready for Interpretation

Select the population and enter the score for at least one DXA site.

Lowest T-score:

Visual Scale (+3.0 to −4.0 SD)

+3 +1 0 −1 −2.5 −4

Normal Low mass Osteoporosis

Site	Score	Category

Clinical Context

Sources: ISCD 2023 Adult Positions, NIAMS/NIH, WHO 1994 criteria.

Not medical advice: This tool categorizes scores for education only. It does not diagnose, estimate fracture probability (use FRAX with a clinician) or replace review of the full DXA report.

BMD to T-Score Calculator

T-score = (BMD − young-adult mean BMD) ÷ young-adult SD. Pick a reference or type the mean and SD printed on your report (lumbar spine references differ by scanner maker, so use your report for the spine).

Reference

BMD (g/cm²)

Mean

T-score—

% of young-adult mean—

WHO category (age 50+)—

BMD at T = −1.0 / −2.5—

NHANES III young white women (Looker 1998), the ISCD/WHO reference for hip T-scores
Site	Mean ± SD	T = −1.0	T = −2.5
Femoral neck	0.858 ± 0.120 g/cm²	0.738 g/cm²	0.558 g/cm²
Total hip	0.942 ± 0.122 g/cm²	0.820 g/cm²	0.637 g/cm²

Worked example: femoral neck BMD 0.650 g/cm² → (0.650 − 0.858) ÷ 0.120 = −1.73, which is low bone mass (osteopenia), 75.8% of the young-adult mean. Scanner software may use slightly different reference values, so the printed T-score on your report takes priority.

Quick answer

The WHO T-score chart classifies a DXA T-score of -1.0 or higher as normal, between -1.0 and -2.5 as low bone mass (osteopenia), and -2.5 or lower as osteoporosis. The lowest score of the lumbar spine, total hip and femoral neck is used. These ranges apply to postmenopausal women and men 50+; younger adults use Z-scores.

Examples

T-score	WHO category
-1.0 or higher	Normal
-1.1 to -2.4	Low bone mass (osteopenia)
-2.5 or lower	Osteoporosis
-2.5 or lower + fragility fracture	Severe (established) osteoporosis

Enter the T-score for each DXA site to get the category.

Summary

This educational tool interprets dual-energy X-ray absorptiometry (DXA) scores with World Health Organization (WHO) and International Society for Clinical Densitometry (ISCD) rules. For postmenopausal women and men 50+, it applies the WHO T-score categories to the lowest of the lumbar spine, total hip and femoral neck (33% radius only when those cannot be used) and flags severe osteoporosis when a fragility fracture is reported. For younger adults it applies the ISCD Z-score wording. A BMD to T-score calculator uses the NHANES III young white women reference (femoral neck 0.858 ± 0.120 g/cm², total hip 0.942 ± 0.122 g/cm²) or a custom mean and SD. It is not medical advice.

How it works

Select the population: T-scores for postmenopausal women and men 50+, Z-scores for premenopausal women, men under 50 and children.
Enter the score for each site on your DXA report: lumbar spine (L1–L4), total hip, femoral neck and, only if those cannot be used, the 33% radius.
The lowest score of spine, total hip and femoral neck is classified: Normal (≥ −1.0), Low bone mass (between −1.0 and −2.5) or Osteoporosis (≤ −2.5); Z ≤ −2.0 is below the expected range for age.
Tick the fragility fracture box to see the WHO severe (established) osteoporosis category and the clinical-diagnosis note.
To convert a BMD value, use T = (BMD − young-adult mean) ÷ young-adult SD with the NHANES III reference or your report's values.

Use cases

Understand a DXA report with several sites before a follow-up visit.
Check which site sets the diagnosis (the lowest of spine, total hip and femoral neck).
Convert femoral neck or total hip BMD in g/cm² to a T-score, for example from a research table.
Read Z-scores correctly for premenopausal women and men under 50.
Teach the WHO and ISCD thresholds to students reviewing densitometry reports.

Frequently Asked Questions

Last updated: 2026-10-09 · Reviewed by Nham Vu