Testosterone Calculator (Men)
Calculate free testosterone + low-T symptom checker
Quick Answer
This calculator estimates your free testosterone (the active form) from total testosterone and SHBG levels. 40% of men over 45 have low testosterone.
Normal ranges: Total T: 300-1000 ng/dL | Free T: 9-30 ng/dL | Below 300 ng/dL = clinically low
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Testosterone FAQ — Everything Men Need to Know
What is a normal testosterone level for men?
Normal total testosterone: 300-1000 ng/dL. Optimal range: 600-900 ng/dL. Below 300 ng/dL = clinically low (hypogonadism). Free testosterone (active form): 9-30 ng/dL. Most men over 40 have declining testosterone (~1-2% per year).
What are the symptoms of low testosterone?
Top 8 low-T symptoms: 1) Low libido/sex drive, 2) Erectile dysfunction, 3) Chronic fatigue, 4) Muscle weakness/loss, 5) Weight gain (especially belly fat), 6) Brain fog/poor concentration, 7) Depression/mood swings, 8) Hair loss. If you have 4+ symptoms, get tested.
How can I increase testosterone naturally?
Top 5 natural testosterone boosters: 1) Lift heavy weights 3-4x/week (squats, deadlifts), 2) Sleep 7-9 hours (testosterone is produced during deep sleep), 3) Eat 1g protein per lb bodyweight, 4) Reduce stress (cortisol kills testosterone), 5) Vitamin D (2000-4000 IU daily).
Does testosterone replacement therapy (TRT) work?
Yes! TRT is highly effective for men with clinically low testosterone (<300 ng/dL). Benefits: increased muscle mass, fat loss, improved libido, better mood, more energy. Requires doctor supervision and regular blood work. Cost: $100-300/month.
What is free testosterone vs total testosterone?
Total testosterone = all testosterone in your blood (98% bound to proteins). Free testosterone = the 2% that's biologically active and usable by your body. Free T is more important — you can have normal total T but low free T and still have symptoms.
What foods boost testosterone?
Top testosterone-boosting foods: red meat, eggs, oysters, fatty fish (salmon), nuts (almonds, Brazil nuts), olive oil, avocados, garlic, ginger, cruciferous vegetables (broccoli, cauliflower). Avoid: soy, alcohol, processed foods, trans fats.
Does exercise increase testosterone?
Yes! Strength training (lifting weights) is the #1 exercise to boost testosterone naturally — increases T by 15-40% post-workout. Best exercises: squats, deadlifts, bench press, rows. Avoid: overtraining, excessive cardio, chronic stress (all lower testosterone).
At what age does testosterone decline?
Testosterone peaks at age 20-30, then declines 1-2% per year after age 30. By age 50, most men have lost 20-30% of peak testosterone. By age 70, 30-40% of men have clinically low testosterone. This is natural but preventable with lifestyle optimization.
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See All →This is not medical advice — talk to your doctor. The sections below are educational only. This calculator does not diagnose low testosterone or any hormone condition, and results should not replace lab testing or guidance from a healthcare provider. Do not start, stop, or change any medication or hormone therapy based on this tool alone.
What Is Testosterone? Role in Men and Women
Testosterone is the primary male sex hormone, but it is important in all bodies. In men, it drives reproductive development, muscle and bone mass, libido, and red blood cell production. In women (who produce it in smaller amounts in the ovaries and adrenal glands), it supports libido, bone strength, and muscle tone.
| Role | What Testosterone Does |
|---|---|
| Reproductive | Libido, sperm production, erectile function |
| Muscle & bone | Builds and maintains muscle and bone mass |
| Metabolism | Influences fat distribution and insulin sensitivity |
| Mood & energy | Supports drive, motivation, and energy |
| Blood | Stimulates red blood cell production |
Most testosterone is bound to proteins in the blood (SHBG and albumin); only about 2 percent is free and biologically active. That is why this calculator estimates free testosterone from total T and SHBG.
Low-T Signs Checklist
The 8 symptoms in the tool above are the most commonly reported signs of low testosterone. Having one or two is usually not a concern — many come and go with stress or sleep. Having four or more that persist for several weeks is a reasonable prompt to talk to your doctor:
- Low libido or reduced sex drive
- Erectile dysfunction
- Chronic fatigue or low energy
- Muscle weakness or loss of muscle
- Increased body fat, especially abdominal
- Brain fog or poor concentration
- Depression, irritability, or mood swings
- Reduced body or facial hair growth
These symptoms overlap with depression, sleep apnea, thyroid disease, and stress — so they do not confirm low testosterone. A doctor confirms it with morning blood tests.
What Affects Testosterone: Sleep, Body Fat, Alcohol, Training
| Factor | Effect on Testosterone |
|---|---|
| Sleep (7–9 hours) | Supports production — most T is made during deep sleep |
| High body fat / obesity | Lowers T — fat converts T to estrogen via aromatase |
| Alcohol (regular/heavy) | Lowers T — affects testicular function and liver |
| Strength training | Raises T acutely and supports healthy levels |
| Chronic stress / high cortisol | Suppresses T — cortisol and T compete |
| Very-low-calorie diets | Can lower T — adequate calories and fats matter |
| Vitamin D / zinc deficiency | Low intake is linked to lower T |
| Age (30+) | Natural decline of ~1–2% per year |
How the Assessment Works
The tool estimates free testosterone from your total testosterone and SHBG (using a Vermeulen-equation approach), then places the result into a band alongside your symptom count:
Formula (educational)
Free T is estimated from Total T, SHBG, and albumin
Bioavailable T = Free T + albumin-bound T
Symptom score = count of checked symptoms (0–8)
| Band | Total T (ng/dL) | Meaning |
|---|---|---|
| Low | Below 300 | Consistent with low T — discuss with your doctor |
| Borderline | 300–400 | Low-normal — lifestyle review and monitor |
| Normal | 400–550 | Normal range — maintain healthy habits |
| Optimal | 550+ | Healthy range — keep current habits |
These bands are educational cut-offs based on common reference ranges, not clinical thresholds. Reference ranges vary by lab, and a doctor interprets your result alongside symptoms, age, and health history.
Natural Levers: Strength, Protein, Sleep, Vitamin D
These habits support healthy testosterone in most men. They are not a treatment for clinically low testosterone:
| Lever | How It Helps |
|---|---|
| Strength training 2–4×/week | Acute T boost; supports muscle and metabolic health |
| Adequate protein | Supports muscle repair and hormone production |
| 7–9 hours of sleep | Most T is produced during deep sleep |
| Vitamin D (if low) | Low vitamin D is linked to low T |
| Zinc and magnesium | Support T production when intake is low |
| Healthy fats | Support hormone synthesis (fats are building blocks) |
| Maintain healthy body fat | Reduces aromatase activity (T to estrogen) |
| Limit alcohol | Heavy drinking lowers T |
Worked Example
A 40-year-old man enters total T = 380 ng/dL and SHBG = 40 nmol/L, and checks 5 symptoms (low libido, fatigue, brain fog, belly fat, mood changes).
Calculation
Total T = 380 → Borderline band (300–400)
Free T estimated from Total T and SHBG
Symptom score = 5/8 (above the 4-symptom prompt)
Band: Borderline with multiple symptoms
This result would prompt a conversation with his doctor — a borderline level with several persistent symptoms warrants a morning blood test to confirm, and a review of sleep, stress, and body fat. The score is a prompt to seek testing, not a diagnosis.
How to Use This Calculator & What to Do With Your Result
How to use it:
- Enter your age, total testosterone, and SHBG from a recent blood test.
- Leave albumin at 4.5 if you do not know it (average value).
- Check any low-T symptoms you have been experiencing.
- Click "Calculate Free Testosterone" to see your estimated levels and band.
What to do with your result:
- If your band is optimal or normal, maintain your sleep, training, and nutrition habits.
- If borderline, review sleep (7–9 hours), strength training, body fat, and alcohol.
- If low, or if you have 4+ persistent symptoms, bring your result to your doctor and ask about a morning testosterone test.
- Use the Hormone Balance Calculator and Sleep Metabolism Calculator to explore related symptoms.
- Do not start any supplement or hormone therapy based on this result alone — talk to your doctor first.
Limitations of This Calculator
- It estimates free testosterone from self-entered lab values — it does not measure testosterone itself.
- The formula is an educational approximation; lab-calculated free T may differ.
- Reference ranges vary by lab — the bands are general, not universal.
- Symptoms are self-reported and overlap with many other conditions (depression, sleep apnea, thyroid disease).
- It does not account for age, medications, pituitary conditions, or timing of the blood draw.
- It cannot diagnose hypogonadism or any hormone condition — that requires lab testing and a doctor to interpret.
When to Get Labs: Doctor Guidance
Talk to your doctor about a testosterone blood test if any of these apply:
- You have 4 or more persistent low-T symptoms lasting several weeks.
- Your calculator result falls in the low or borderline band.
- You have risk factors: obesity, type 2 diabetes, sleep apnea, or a family history of hormone disorders.
- You have rapid, unexplained changes in libido, energy, or body composition.
Testosterone is tested with a morning blood draw (levels peak in the morning). A low result is usually confirmed with a second test, and your doctor may order LH, FSH, prolactin, or other tests to find the cause.
Disclaimer: This testosterone calculator provides an educational estimate of free testosterone and a symptom check. It does not diagnose low testosterone, hypogonadism, or any hormone condition, and does not recommend or adjust any medication or hormone therapy, including TRT. Only a healthcare provider can order and interpret lab tests and set a treatment plan. This is not medical advice — talk to your doctor.