Hormones and performance
Testosterone Levels by Age: What's Normal in the UK
Reviewed by a qualified clinician · analysed at UKAS-accredited UK labs (ISO 15189)
Last reviewed April 202614 min read
Every Helvy guide is written by our health editors, then checked by a qualified clinician before it goes live and re-checked as the science moves. We name clinical roles, not individuals, until each reviewer has agreed to be credited publicly. This is wellness guidance to help you understand your own data, not a diagnosis.
Quick answer
For UK men aged 18 to 49, total testosterone typically falls between 8.7 and 29 nmol/L. It narrows to 6.7 to 25.7 nmol/L from age 50, and averages around 17 nmol/L at peak. BSSM guidance treats below 8 nmol/L as likely deficiency. It treats 8 to 12 nmol/L as a grey zone that needs repeat morning testing.
You've had a blood test. The result says 14 nmol/L and your GP says “normal.” But you feel sluggish, your training has stalled, and your recovery is worse than it was five years ago. So is 14 actually normal — or is your GP comparing you to a reference range built from sick 80‑year‑olds?
This guide explains what testosterone levels actually look like across your lifespan, the clinical thresholds that matter, and when “normal” doesn't mean optimal. Based on 2023 BSSM guidelines, NHS reference ranges, and peer-reviewed research.
By the Helvy Medical Team · Reviewed by a qualified clinician · 14 min read
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Build my test1. What does testosterone actually do?
Testosterone is the primary androgen in both men and women. In men, it's produced mainly by the Leydig cells in the testes, regulated by luteinising hormone (LH) from the pituitary gland. Women produce smaller quantities in the ovaries and adrenal glands.
Beyond muscle mass and sex drive, testosterone regulates bone density, red blood cell production, fat distribution, mood, and cognitive function. Low levels are associated with increased cardiovascular risk, type 2 diabetes, osteoporosis, and depression — not just “feeling a bit tired.”
The challenge isn't whether testosterone matters. It's that the reference ranges used by most UK labs are very wide (6–27 nmol/L in some NHS labs). That range is broad enough that a 25‑year‑old athlete and a 75‑year‑old with metabolic syndrome can both be told they're “normal.” Understanding what your level means for your age is the first step.
2. Normal testosterone levels by age (nmol/L)
The table below shows total testosterone reference ranges for men, based on data from the British Society for Sexual Medicine (BSSM) and UK laboratory standards. All values are in nmol/L — the standard unit used by UK labs.
| AGE | TYPICAL RANGE | NOTES |
|---|---|---|
| 18–29 | 8.7–29.0 nmol/L | Peak production. Average ~17.5 nmol/L |
| 30–39 | 8.7–29.0 nmol/L | Gradual decline begins in some men. Average ~17.3 nmol/L |
| 40–49 | 8.7–29.0 nmol/L | Range unchanged, but SHBG rises — free T may be lower. Average ~16.8 nmol/L |
| 50–59 | 6.7–25.7 nmol/L | Reference range narrows. Average ~16.5 nmol/L |
| 60–69 | 6.7–25.7 nmol/L | More men enter the grey zone. Average ~16.4 nmol/L |
| 70+ | 6.7–25.7 nmol/L | Higher comorbidity confounds readings. Average ~14–15 nmol/L |
Average total testosterone by age (nmol/L)
17.5
18–29
17.3
30–39
16.8
40–49
16.5
50–59
16.4
60–69
14.5
70+
In healthy men the average barely moves with age — most of the population-level decline tracks rising obesity and illness, not birthdays.
Illustrative reference against a typical adult range. Below 8 nmol/L is widely treated as likely deficiency and 8–12 as a grey zone. Discuss your own results with a qualified clinician.
UNIT CONVERSION
UK labs report in nmol/L. US labs use ng/dL. To convert: nmol/L × 28.842 = ng/dL. So 15 nmol/L ≈ 433 ng/dL. If you're reading American content (most of what Google surfaces), this conversion is essential.
Note that NHS lab ranges vary. North Bristol NHS Trust uses 6–27 nmol/L. Other trusts use 8.7–29 nmol/L. This inconsistency is itself a problem — a man at 7 nmol/L could be flagged as low at one hospital and “normal” at another. This is why clinical context matters more than the number alone. A reading above the top of the range has its own meaning too — see our guide to high testosterone in men for what drives it and why above-range is not better.
3. Does testosterone really decline 1% per year?
You'll read everywhere that testosterone drops 1–2% per year after 30. It's repeated so often it's treated as biological law. But the evidence is more nuanced.
A 2014 study published in the European Journal of Endocrinology built validated age-specific reference ranges from healthy men and found no significant decline in total testosterone after age 40 in men who remained healthy, non-obese, and free of chronic illness. The population-level decline is largely driven by rising rates of obesity, type 2 diabetes, and medication use. Age itself is not the main cause.
This matters because it reframes the conversation. If your testosterone is 11 nmol/L at 45, the answer isn't necessarily “that's just ageing.” It may be that your body composition, sleep, or metabolic health is driving the decline — and those are modifiable. Once that decline starts to cause symptoms, it is what people loosely call the male menopause, and a blood test is what separates it from ordinary ageing.
The BSSM 2023 guidelines agree: “The decline in testosterone with ageing is predominantly explained by comorbidities, particularly obesity.”
“Although testosterone levels fall as men age, the decline is steady at about 1% a year from around the age of 30 to 40, and this is unlikely to cause any problems in itself.”
— NHS, Male menopause (andropause)
4. Free testosterone vs total: which matters more?
Total testosterone measures everything in your blood. But only 2–3% of it is “free” (unbound and biologically active). The rest is bound to SHBG (sex hormone-binding globulin) (~60–70%) or albumin (~30–40%).
Here's why this matters in practice: a man with total testosterone of 15 nmol/L and SHBG of 20 nmol/L has plenty of free testosterone available. Now take the same total T with SHBG of 60 nmol/L. Most of that testosterone is locked up and inactive. He could have genuine androgen deficiency symptoms despite a “normal” total T reading.
The BSSM recommends measuring free testosterone when total T is in the grey zone (8–12 nmol/L) or when SHBG is suspected to be abnormal. A free testosterone below 0.225 nmol/L is considered low. Our free testosterone guide covers how it is calculated and what the thresholds mean.
Conditions that raise SHBG (and therefore lower free T): ageing, hyperthyroidism, liver disease, anticonvulsants, and oestrogen therapy. Conditions that lower SHBG: obesity, type 2 diabetes, hypothyroidism, and anabolic steroid use. This is why testing SHBG alongside testosterone gives a far more complete picture than total T alone. For the full breakdown — normal free testosterone levels, calculated vs measured free T, and the result patterns that matter — see our guide to free testosterone vs total. And if a high SHBG is what is holding your free testosterone down, our guide to increasing free testosterone by lowering SHBG covers what actually moves it.
5. The grey zone: 8–12 nmol/L explained
The BSSM practical guidelines define three clinical thresholds for total testosterone:
ABOVE 12 NMOL/L
Testosterone deficiency is unlikely to be the cause of symptoms. Look elsewhere — thyroid function, iron, vitamin D, cortisol, sleep disorders.
8–12 NMOL/L — THE GREY ZONE
A trial of testosterone replacement therapy (TRT) may be appropriate if symptoms are present andfree testosterone is also low (<0.225 nmol/L). Repeat testing is essential — a single reading in this range isn't enough for diagnosis. Morning fasting sample required.
BELOW 8 NMOL/L
Testosterone deficiency is likely and treatment is usually indicated. If below 5.2 nmol/L with low LH/FSH or raised prolactin, pituitary MRI is recommended to rule out a tumour.
The grey zone is where most men who “feel low T” will land — and where most GPs will say “it's normal.” Understanding this clinical framework lets you have an informed conversation with your doctor rather than accepting a dismissive “it's fine.” If your own result landed here, our guide to borderline testosterone results walks through the exact steps to confirm it.
6. At what testosterone level do symptoms appear?
Symptoms don't suddenly appear at a single threshold. They emerge progressively as levels fall. Based on clinical data cited in the BSSM 2023 review:
| TOTAL T | COMMON SYMPTOMS |
|---|---|
| <15 nmol/L | Reduced energy, slower recovery from exercise, declining motivation |
| <12 nmol/L | Increased body fat (especially visceral), reduced muscle mass, irritability |
| <10 nmol/L | Low mood, poor concentration, sleep disturbance, loss of morning erections |
| <8 nmol/L | Erectile dysfunction, significant fatigue, hot flushes, reduced bone density |
These thresholds are approximate and individual variation is real. Some men function well at 12 nmol/L; others feel terrible at 16. This is exactly why baseline testing in your 20s or 30s is valuable. If your personal level was 25 and it's now 14, that's a big relativedecline even if the absolute number is “normal.” If you are under 40 and your level is genuinely low, the cause is rarely age: see our guide to low testosterone in young men. Whatever your age, a low number always has a reason worth finding — our guide to what causes low testosterone walks through the common, reversible causes and the medical ones.
7. What tanks your testosterone (and it's not just age)
If the “1% per year” decline is largely driven by lifestyle and health status, what exactly causes it? These are the biggest factors you can change, plus the medication-related ones:
BODY COMPOSITION
Adipose tissue contains aromatase, an enzyme that converts testosterone to oestradiol. Higher body fat = more conversion = lower testosterone. The relationship is bidirectional — low T also promotes fat storage, creating a self-reinforcing cycle. Losing visceral fat is the single most effective natural intervention.
SLEEP DEPRIVATION
Testosterone is primarily produced during sleep. A 2011 JAMA study found that restricting sleep to 5 hours per night for one week reduced testosterone by 10–15% in young healthy men. This is equivalent to 10–15 years of ageing, achieved in 7 days. Our guide to sleep and testosterone covers the mechanism, the sleep apnoea link and how to test.
MEDICATIONS
Several common prescriptions suppress testosterone: opioid painkillers (severe suppression), SSRIs and SNRIs (moderate), corticosteroids including inhaled steroids (dose-dependent), finasteride/dutasteride (blocks DHT conversion but can affect total T), and long-term PPI use. If you're on any of these and experiencing symptoms, discuss with your prescriber before assuming it's age-related.
CHRONIC STRESS & CORTISOL
Cortisol and testosterone have an inverse relationship. Chronically raised cortisol — from overtraining, work stress, or poor sleep — directly suppresses the HPG axis. Men who overtrain without enough recovery often show low testosterone despite being “healthy.”
METABOLIC DYSFUNCTION
Insulin resistance and type 2 diabetes are independently associated with low testosterone. Monitoring HbA1c and fasting glucose alongside testosterone gives a more complete metabolic picture.
8. When and how to test (timing matters)
Testosterone follows a circadian rhythm: it peaks between 7–10am and can be 30% lower by late afternoon. If your blood was drawn at 4pm, your result could be much lower than the true morning value.
The BSSM guidelines are specific: testosterone should be measured from a fasting morning blood sample, ideally before 10am. A single low result must be confirmed with a repeat testat least 4 weeks later — levels fluctuate day to day and a single snapshot isn't diagnostic. See our guide to the best time to test testosterone for the full timing and fasting checklist.
What to request (or what your test should include):
- Total testosterone— the headline number
- SHBG — to calculate free testosterone
- Free testosterone(calculated or measured) — the biologically active fraction
- LH and FSH— to distinguish between primary (testicular) and secondary (pituitary) causes
- Prolactin— elevated levels suggest pituitary pathology
- Thyroid function (TSH) — thyroid disorders mimic low-T symptoms
Our Complete Male Hormones panel includes testosterone, SHBG, free testosterone, and DHEA-S alongside LH, FSH and prolactin — giving you the context needed to interpret your testosterone result properly.
9. What happens if your levels are low? The UK pathway
If you go to your GP with suspected low testosterone, here's the typical NHS pathway:
- Initial blood test— total testosterone, usually at the GP surgery. Many GPs don't specify morning/fasting, which can produce a falsely low result.
- Repeat blood test— if the first is low, a confirmatory fasting morning sample is requested 4–6 weeks later. LH, FSH, prolactin, and thyroid function should be included.
- Endocrinology referral— if confirmed low, you're referred to an endocrinologist. Current NHS wait times: 3–6 months in most areas.
- Treatment decision— if TRT is indicated, options include testosterone gel (Testogel/Tostran), injections (Sustanon or Nebido), or patches. Treatment is lifelong and affects fertility.
The gap between step 1 and treatment can be 6–12 months on the NHS. This is one reason men opt for private blood testing — not to self-prescribe TRT, but to arrive at the GP appointment with full, correctly-timed blood results. Clear results remove doubt and speed up the referral pathway. For the detail on when the NHS will and won't test, see our guide to getting a testosterone test on the NHS.
10. Testosterone in women: the overlooked hormone
Testosterone isn't just a male hormone. Women produce it in smaller quantities, and it plays a critical role in energy, libido, bone density, and mood. Women's testosterone is often overlooked because the reference ranges are narrow and many GPs don't routinely test it.
| CONTEXT | RANGE |
|---|---|
| Premenopausal | 0.5–2.4 nmol/L |
| Postmenopausal | 0.3–1.7 nmol/L (often lower) |
| PCOS (elevated) | >2.7 nmol/L may indicate hyperandrogenism |
| On testosterone therapy | Target <1.5 nmol/L (reduce dose if exceeded) |
NICE menopause guidance (NG23) now recommends that testosterone supplementation can be considered for menopausal women with low sexual desire when HRT alone hasn't worked. No testosterone products are currently licensed for women in the UK — all prescribing is off-label, which is one reason many GPs won't initiate it.
On the other end, raised testosterone in women is one of the diagnostic criteria for polycystic ovary syndrome (PCOS), which affects about 1 in 10 women in the UK.
11. How to raise testosterone naturally (what actually works)
Before considering TRT, these interventions have genuine clinical evidence behind them. They're listed in order of effect size, and our full guide on how to raise testosterone naturally covers each in depth, including the role of zinc when your levels are low. For the diet specifics, see our guide to foods that increase testosterone.
RESISTANCE TRAINING
Compound lifts (squats, deadlifts, presses) at moderate to high intensity acutely raise testosterone and chronically improve body composition. The hormonal benefit comes from reducing body fat and increasing lean mass, not from the acute post-workout spike.
BODY FAT REDUCTION
Losing 10% of body weight can increase testosterone by 2–3 nmol/L in overweight men. This is the most powerful change you can make without drugs. But there is a limit. Very low-calorie diets (<1,200 kcal/day) or long bouts of endurance training can lower testosterone. The body reads near-starvation as a signal to suppress reproduction.
SLEEP OPTIMISATION
7–9 hours consistently. Testosterone production peaks during deep (N3) sleep. Improving sleep quality — consistent schedule, dark room, no screens before bed, treating sleep apnoea if present — is as important as sleep duration.
TARGETED SUPPLEMENTATION
Only if blood tests confirm a deficiency. Vitamin D (if below 50 nmol/L), zinc (if deficient), and magnesium all support testosterone production when correcting a documented deficiency. “Testosterone boosters” without a confirmed deficiency to fix are largely a waste of money.
ALCOHOL REDUCTION
Chronic alcohol consumption suppresses testicular testosterone production and raises SHBG. Even moderate drinking (3–4 units per day) has a measurable suppressive effect. Reducing alcohol is one of the simplest, highest-impact changes you can make.
Frequently asked questions
What is a good testosterone level for a 30-year-old man?
The reference range for men aged 18–49 is 8.7–29.0 nmol/L, with an average around 17–18 nmol/L. However, “good” depends on your personal baseline and symptoms. A 30-year-old at 12 nmol/L is within range but at the lower end. If he previously tested at 22, that's a big drop worth looking into. Anything above 15 nmol/L is generally seen as healthy for this age group.
Can you test testosterone at home?
Yes. Home finger-prick blood tests can accurately measure total testosterone when processed by a UKAS-accredited lab. The key requirement is timing — take the sample in the morning, ideally before 10am and while fasting. Our test kits include clear timing instructions and are analysed by NHS laboratories.
Is 15 nmol/L low testosterone?
No — 15 nmol/L is within the normal range and above the BSSM threshold of 12 nmol/L. However, if you're experiencing symptoms of low energy, reduced libido, or poor recovery, it's worth checking your SHBG and free testosterone. A total T of 15 with very high SHBG could still mean your biologically active testosterone is insufficient.
How much does a testosterone blood test cost in the UK?
An NHS GP blood test is free but may have long waits and typically only measures total testosterone. Private home tests range from £30–£50 for testosterone alone to £100–£150 for a comprehensive hormone panel including SHBG, cortisol, DHEA-S, and thyroid function. Our Complete Male Hormones panel (£119) includes testosterone alongside 8 related hormone markers.
Does testosterone replacement therapy have side effects?
Yes. TRT suppresses natural production (LH and FSH drop), which causes testicular atrophy and significantly reduces fertility — it is effectively a male contraceptive. Other potential effects include polycythaemia (raised red blood cell count, monitored via regular full blood count), acne, sleep apnoea worsening, and mood changes. Treatment requires ongoing monitoring and is considered lifelong. This is why thorough blood testing before starting TRT is critical.
Should I test testosterone if I feel fine?
If you're in your 20s or 30s and feel healthy, a baseline measurement is still valuable. Testosterone decline is gradual, and you won't notice it until the gap between your current level and your peak is large enough to cause symptoms. Having a baseline means any future test can show your personal trend, not just where you sit on a population-wide reference range.
Check your testosterone levels
Our Complete Male Hormones panel (£119) includes testosterone, SHBG, free testosterone, LH, FSH, prolactin and DHEA-S. Home finger-prick kit, results in 5 working days, from UKAS-accredited UK laboratories.
Medical disclaimer:This content is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Reference ranges cited in this guide are based on BSSM guidelines and published research. They may differ from the ranges used by your local NHS laboratory. Do not make changes to medication, supplementation, or treatment plans based solely on information in this article — consult your GP or a qualified healthcare professional. All Helvy blood tests are processed by UKAS-accredited laboratories to ISO 15189.
Last updated: April 2026 · By Helvy · Medically analysed at UKAS-accredited UK laboratories
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