UK labs report testosterone in nmol/L. Enter your result below to see which range it falls in and what UK guidelines say about it — then read why a single number, on its own, is not a diagnosis.
A total testosterone below 12 nmol/L is consistent with testosterone deficiency — Tier 1 under the BSSM/ISSM classification. Together with symptoms such as low energy, low sex drive, or changes to mood and sleep, this is the range where treatment is usually appropriate.
This is the borderline range — Tier 2. A number here does not settle the question on its own, and it is not an automatic no: our clinicians treat within this range where symptoms and the wider clinical picture support it. Free testosterone matters here, because a high SHBG can leave plenty of total testosterone bound up and unusable.
A total of 14 nmol/L or above sits within the usual adult male range and makes testosterone deficiency unlikely as the explanation for symptoms. One exception matters: a free testosterone below 0.225 nmol/L counts as deficient on its own, whatever the total says.
This is above the usual adult male range. In someone not on treatment it is worth repeating, since assay variation and sample timing can both inflate a result.
Ranges vary slightly between laboratories, so read your own report's reference range alongside this. The thresholds above follow the British Society for Sexual Medicine guideline on adult testosterone deficiency.
Most people are looking up a value between 10 and 20 nmol/L — and the 12–14 band is where the answer genuinely depends on more than the total.
| Result | ng/dL | Range | What it suggests |
|---|---|---|---|
| 6 nmol/L | 173 | Below 12 nmol/L | Consistent with testosterone deficiency. Confirm with a second morning test. |
| 8 nmol/L | 231 | Below 12 nmol/L | Consistent with testosterone deficiency. Confirm with a second morning test. |
| 9 nmol/L | 260 | Below 12 nmol/L | Consistent with testosterone deficiency. Confirm with a second morning test. |
| 10 nmol/L | 288 | Below 12 nmol/L | Consistent with testosterone deficiency. Confirm with a second morning test. |
| 11 nmol/L | 317 | Below 12 nmol/L | Consistent with testosterone deficiency. Confirm with a second morning test. |
| 12 nmol/L | 346 | 12 – 14 nmol/L | Borderline. Treatable where symptoms and free testosterone support it. |
| 13 nmol/L | 375 | 12 – 14 nmol/L | Borderline. Treatable where symptoms and free testosterone support it. |
| 14 nmol/L | 404 | 14 – 30 nmol/L | Within the usual range, unless free testosterone is low. |
| 15 nmol/L | 433 | 14 – 30 nmol/L | Within the usual range, unless free testosterone is low. |
| 16 nmol/L | 461 | 14 – 30 nmol/L | Within the usual range, unless free testosterone is low. |
| 18 nmol/L | 519 | 14 – 30 nmol/L | Within the usual range, unless free testosterone is low. |
| 20 nmol/L | 577 | 14 – 30 nmol/L | Within the usual range, unless free testosterone is low. |
| 23 nmol/L | 663 | 14 – 30 nmol/L | Within the usual range, unless free testosterone is low. |
| 25 nmol/L | 721 | 14 – 30 nmol/L | Within the usual range, unless free testosterone is low. |
| 30 nmol/L | 865 | Above 30 nmol/L | Above the usual range. Worth repeating. |
Most testosterone in your blood is bound to a protein called SHBG and cannot be used. Only the free and albumin-bound portion is available to your body. If your SHBG is high, your total can sit comfortably above 14 nmol/L while your free testosterone is genuinely low — which is why free testosterone matters most in the 12–14 range, and why a free level below 0.225 nmol/L (225 pmol/L) is treated as deficient on its own, whatever the total says.
Testosterone peaks in the morning and falls through the day — an afternoon sample can read several nmol/L lower than the same man tested at 8am. Guidelines ask for a morning sample, ideally before 11am.
Levels vary day to day. UK guidance requires two separate morning samples before testosterone deficiency is diagnosed, which is why a single low reading is a reason to retest rather than to start treatment.
Testosterone drops during illness, after surgery and under acute stress. A result taken while you were unwell is worth repeating once you have recovered.
Sex hormone binding globulin holds testosterone in a form your body cannot use. High SHBG can produce a reassuring total alongside a genuinely low free testosterone; low SHBG does the reverse. A free testosterone below 0.225 nmol/L is treated as deficient on its own, whatever the total says.
An at-home finger-prick test measures your total testosterone, the single figure that determines eligibility for treatment. Once a clinician has your total, they can arrange SHBG measurement if needed to work out how much testosterone your body can actually use.
Check your testosterone at homeResults in 2–3 working days. Free UK delivery.
This page explains what published reference ranges say about a number. It is not a diagnosis and it is not medical advice. Testosterone deficiency is diagnosed on two separate morning blood samples together with your symptoms, by a doctor. If you feel unwell, speak to a clinician rather than acting on a result alone.
