TRT Calculator

Testosterone Dosage Calculator

Calculate the exact volume to draw from your testosterone vial based on your prescribed dose and vial concentration. Supports every-N-days, weekly, 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

Concentration100 mg dose150 mg dose200 mg dose
100 mg/mL1.00 mL1.50 mL2.00 mL
200 mg/mL0.50 mL0.75 mL1.00 mL
250 mg/mL0.40 mL0.60 mL0.80 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.

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