TRT Dose Calculator for Sustanon, Nebido & Enantate
Work out your injection volume and weekly-equivalent dose from your prescribed UK product, in mg/ml and nmol/L. Pick Sustanon 250, Nebido, or Testosterone Enantate, enter your prescribed dose, and read the volume per injection.
TRT Dose Calculator
Sustanon 250, Nebido, and Testosterone Enantate (UK products)
Enter your prescribed dose. This calculator works out injection volume — it does not recommend a dose.
Sustanon 250: 250 mg/ml, 1 ml ampoule
The total weekly dose set by your GP or private clinic.
Nebido is given every 10–14 weeks in clinic. Sustanon and Enantate are typically once or twice weekly when self-administered.
Draw per injection
0.25 ml
= 25 units on a U-100 insulin syringe
62.5 mg per injection · 125 mg weekly equivalent
For educational and research purposes only. This calculator provides estimates based on standard formulas.
Always verify calculations with your healthcare provider before use. We assume no liability for dosing errors, adverse events, or outcomes resulting from use of this tool.
Working it out for each UK product
The three injectable testosterone products licensed in the UK all happen to share the same 250 mg/ml concentration, which keeps the maths consistent across them. What changes is the ester (and therefore the half-life and injection frequency), not the volume per mg.
Sustanon 250
Sustanon 250 is supplied as a 1 ml ampoule at 250 mg/ml, containing 250 mg of testosterone as a blend of four esters (propionate, phenylpropionate, isocaproate, decanoate). A full ampoule is 250 mg; half an ampoule is 0.5 ml or 125 mg.
Nebido (testosterone undecanoate)
Nebido is supplied as a 4 ml vial containing 1000 mg of testosterone undecanoate — 250 mg/ml. The standard NHS and private-clinic protocol administers the full 4 ml as a single deep intramuscular injection, repeated every 10 to 14 weeks at steady state.
Testosterone Enantate
Testosterone Enantate is supplied as a 1 ml ampoule at 250 mg/ml. With a half-life around 4.5 days, most UK private clinics split the weekly dose into two injections — for example 0.5 ml twice weekly delivers 250 mg per week.
NHS vs private clinic, briefly
TRT in the UK is accessed through the NHS — a GP-led pathway involving morning blood tests, an endocrinology referral and often a shared-care agreement back to your GP — or through a private clinic. Sustanon and Nebido are the most commonly prescribed injectables on the NHS; private clinics also prescribe Enantate and offer more flexible frequencies (twice-weekly or daily microdosing). Testosterone is a prescription-only medicine in the UK, and this tool helps you work with whatever protocol your prescriber has set rather than recommend one.
For the longer write-up of the two pathways, see the NHS vs private clinic guide. For UK-specific blood test guidance and nmol/L thresholds, see the testosterone blood test guide.
Frequently asked questions
What concentration is Sustanon 250?
Sustanon 250 is 250 mg/ml, supplied in a 1 ml ampoule. Each ampoule contains 250 mg of testosterone (a blend of four esters: propionate, phenylpropionate, isocaproate and decanoate).
How much testosterone is in a Nebido vial?
Nebido contains 1000 mg of testosterone undecanoate in a 4 ml vial — that is 250 mg/ml. The standard administration is the full 4 ml vial given as a deep intramuscular injection in a clinic, repeated every 10 to 14 weeks once steady state is reached.
What units is testosterone measured in the UK?
Blood testosterone in the UK is reported in nmol/L. NHS biochemistry labs and NICE guidance use nmol/L throughout. The US convention of ng/dL is rarely used by UK GPs or private clinics. To convert: 1 ng/dL ≈ 0.0347 nmol/L.
How do I convert my prescribed dose to ml?
Use the calculator above. Enter your prescribed dose in mg, pick your UK product (which auto-fills the mg/ml concentration), and select how often you inject. The calculator returns the volume in ml and the equivalent units on a 100-unit insulin syringe.
Is this medical advice?
No. This tool helps you visualise the protocol you have already been prescribed. Dosing decisions, blood test interpretation and any change to your TRT regimen are between you and your GP or private clinic. Testosterone is a prescription-only medicine in the UK.
How to use this calculator
Pick your UK product
Sustanon 250, Nebido, Testosterone Enantate, or enter a custom mg/ml.
Enter your prescribed dose
Weekly total (mg) or per-injection dose (mg) from your prescriber.
Select injection frequency
Once weekly, twice weekly, every other day, or every 10 weeks for Nebido.
Read the volume
ml per injection plus the equivalent units on a 100-unit insulin syringe.
Related Tools
TRT Tracker (UK)
Log every Sustanon, Nebido or Enantate injection on the Regimen app.
Sustanon and Nebido UK Guide
How the two main UK injectables compare for self-administered TRT.
NHS vs Private Clinic TRT Guide
Costs, wait times and what to expect on each pathway.
Testosterone Blood Test UK Guide
What to ask for, nmol/L thresholds, and timing.
Log every Sustanon, Nebido or Enantate injection
Regimen tracks the protocol your GP or private clinic has set, with reminders, site rotation and blood-test trends in nmol/L.
- Built-in dose calculators
- Injection reminders
- Bloods trended in nmol/L
- Private, secure health data
