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T-score explained: your bone density number, decoded

What a T-score of −2.5 means, the normal ranges, and how it differs from a Z-score.

4 min read · Medically reviewed by Dr. Emily Warren, DPT · Updated July 2026

Doctor of Physical Therapy (DPT) · BoneFit®-certified (Osteoporosis Canada) · LIFTMOR protocol–trained · Credentialed McKenzie (MDT) therapist · Mindful Movement Physical Therapies

Key takeaways

  • A T-score compares your bone density to that of a healthy 30-year-old adult.
  • −1.0 or higher is normal; −1.0 to −2.5 is osteopenia; −2.5 or lower is osteoporosis.
  • Fracture risk roughly 1.5–2× for each 1-point drop in T-score, but it's only one part of overall fracture risk.

A T-score compares your bone density to that of a healthy young adult at peak bone mass. A T-score of −1.0 or higher is normal; between −1.0 and −2.5 is osteopenia (low bone mass); and −2.5 or lower is osteoporosis. The score comes from a DXA (DEXA) scan, usually of the spine and hip.

The bone density chart

T-scoreCategoryWhat it means
−1.0 or higherNormalBone density is in the healthy range.
−1.0 to −2.5OsteopeniaLow bone mass — an early warning stage, not yet osteoporosis.
−2.5 or lowerOsteoporosisBone density is low enough that bones fracture more easily.
−2.5 or lower + a fragility fractureSevere osteoporosisOsteoporosis plus one or more low-trauma fractures.

What a T-score of −2.5 means

A T-score of −2.5 sits right at the threshold for osteoporosis: your bone density is about 2.5 standard deviations below the young-adult average. Fracture risk rises as the score falls — roughly 1.5 to 2 times for each 1-point drop — but your T-score is only one input. Age, prior fractures, family history and fall risk all feed into overall fracture risk (tools like FRAX combine them).

T-score vs Z-score

A T-score compares you to a young-adult reference and is used to diagnose osteoporosis in postmenopausal women and men over 50. A Z-score compares you to people of your own age and sex, and is used for younger adults, children, and premenopausal women. If your Z-score is unusually low, providers look for secondary causes of bone loss.

Your T-score tells you where you stand — it doesn't have to be where you stay. Bone responds to progressive loading, so a diagnosis is a starting point for action, not a life sentence.

Frequently asked questions

What does a T-score of −2.5 mean?

A T-score of −2.5 is the threshold for osteoporosis — your bone density is about 2.5 standard deviations below that of a healthy young adult. It means bones are more likely to fracture, and it's usually the point at which providers consider treatment alongside exercise and nutrition.

What is a normal T-score by age?

The T-score categories don't change with age: −1.0 or higher is always classified as normal, −1.0 to −2.5 as osteopenia, and −2.5 or lower as osteoporosis. However, average bone density declines with age, so older adults are statistically more likely to fall into the osteopenia or osteoporosis ranges. For comparison to your own age group, providers use the Z-score.

Can a T-score improve?

Yes, modestly. Progressive resistance and impact training, adequate calcium and vitamin D, and (when prescribed) medication can increase bone mineral density over 6–12 months, and for some people that's enough to move a T-score from the osteoporosis range back toward osteopenia. Large jumps are uncommon; the bigger goal is halting loss and reducing fracture risk.

Sources

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