Last updated: May 2026
Testosterone Injection Calculator
About this calculator
The TRT dose calculator converts a prescribed testosterone dose into the exact volume to draw from a vial using the formula Volume (mL) = Dose (mg) ÷ Concentration (mg/mL). It is built for people managing an active TRT protocol — enter your vial concentration and prescribed dose to get your draw volume instantly. Supports weekly, every-N-days, and mL-to-mg modes. Free, instant, no login.
How to use this calculator
You need three pieces of information from your prescription and vial label: the vial concentration (mg/mL), your prescribed dose (mg), and how often you inject.
Select your mode — Weekly dose if your doctor gave you a weekly amount, Every N days if you inject on a fixed interval, or mL to mg if you want to verify what a drawn volume corresponds to in milligrams.
Enter your values and the result updates immediately. The calculator also shows syringe fill level so you can cross-check what you see in the barrel.
Worked example
Example — weekly injection
Vial concentration: 200 mg/mL (testosterone cypionate)
Prescribed weekly dose: 100 mg
Injection frequency: once per week
Draw = 100 ÷ 200 = 0.50 mL
Example — twice-weekly (every 3.5 days)
Vial concentration: 200 mg/mL
Prescribed weekly dose: 160 mg
Interval: 3.5 days (twice per week)
Per-injection dose = 80 mg → Draw = 80 ÷ 200 = 0.40 mL
How to interpret your result
The result is the volume in mL to draw from your vial for each injection. On a standard 1mL (U-100) insulin syringe, 0.5mL corresponds to the 50-unit mark. On a 3mL syringe, 0.5mL is at the 0.5 mark on the barrel.
Always verify the drawn volume against the syringe markings before injecting. The calculator is a maths tool — always confirm dosing with your prescribing doctor or pharmacist.
Common vial concentrations
| Concentration | 100 mg dose | 150 mg dose | 200 mg dose |
|---|
| 100 mg/mL | 1.00 mL | 1.50 mL | 2.00 mL |
| 200 mg/mL | 0.50 mL | 0.75 mL | 1.00 mL |
| 250 mg/mL | 0.40 mL | 0.60 mL | 0.80 mL |
Frequently asked questions
What is vial concentration?
Vial concentration is the strength of your testosterone preparation, expressed in mg per mL. Common values are 100 mg/mL and 200 mg/mL. It is printed on the vial label — look for the format "200 mg/mL" or "200 mg/1mL".
What is the formula the calculator uses?
Volume (mL) = Dose (mg) ÷ Concentration (mg/mL). This is standard pharmaceutical dilution maths. The calculator applies this formula exactly — no adjustments or estimations.
What if I inject every 3.5 days?
Use the "Every N days" mode. Enter 3.5 as your interval and your total weekly prescribed dose. The calculator splits the weekly dose proportionally (weekly dose ÷ 7 × interval) and returns the volume per injection.
Can I use this for testosterone enanthate, cypionate, or propionate?
Yes. The calculator works for any oil-based testosterone ester. The only inputs that matter are the concentration on your specific vial label and your prescribed dose — the ester type does not change the maths.
My result shows 0.08 mL — how do I measure that accurately on my syringe?
A volume of 0.08 mL equals 8 units on a U-100 insulin syringe. Standard 0.3 mL syringes (30-unit capacity) have 1-unit graduation marks, so 8 units is visible and measurable. For very small draws, pull the plunger slowly past your mark then push back to the exact line — this clears air from the needle tip and gives a more accurate read. If you consistently draw under 0.10 mL, ask your pharmacy whether a lower-concentration vial (e.g., 100 mg/mL instead of 200 mg/mL) is available — halving the concentration doubles your draw volume for the same dose, making it easier to measure precisely.
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