Last updated: May 2026

Testosterone Dosage Calculator — mg to mL & Syringe Units

Quick answer: A 100 mg weekly dose from a 200 mg/mL vial is 100 ÷ 200 = 0.50 mL, which sits at the 50-unit mark on a U-100 insulin syringe. Formula: Volume (mL) = Dose (mg) ÷ Concentration (mg/mL).

About this calculator

This testosterone dosage calculator converts a prescribed dose and vial concentration into the volume to draw in mL and the matching U-100 syringe units using Volume (mL) = Dose (mg) ÷ Concentration (mg/mL). It performs arithmetic only; enter the dose and schedule supplied by your prescriber, then confirm the result and injection technique with your prescriber or pharmacist.

On a very low or sub-therapeutic dose? If you're following a women's low-dose protocol, use the dedicated women's low-dose testosterone microdosing calculator — it supports dose increments down to 0.5 mg/week and the small draw volumes those protocols need.

Starting TRT for the first time? The starting TRT practical checklist walks through baseline labs, the dose and frequency decision, supplies and the unit maths before your first injection.

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

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

Choosing the right syringe for Testosterone (TRT)

Once you know your draw volume, the syringe you use determines how accurately you can measure it. Most Testosterone (TRT) injections fall between 0.25 mL and 1 mL. A 1 mL (U-100) insulin syringe is graduated in single units (0.01 mL), which makes small or fractional volumes easy to read — well suited to subcutaneous and shallow intramuscular injections. A 3 mL syringe holds more and is often used when drawing from a multi-dose vial, but its wider barrel makes very small volumes harder to measure precisely.

Many people draw the dose with one needle and switch to a fresh, finer needle to inject. Needle gauge and length depend on your injection site and body composition, not on the calculator's output — the testosterone injection sites guide covers site selection, and Testosterone (TRT) protocols explained shows how injection frequency affects the volume per shot. Always confirm your technique and equipment with your prescriber or pharmacist.

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How this is calculated

Supported modes are Every N Days, Per Week, and mL to mg. Dose ÷ strength gives mL; mL × strength reverses to mg; mL × 100 gives U-100 units. Results are rounded for readability and syringe marking only, and ester choice does not change volume maths. It is arithmetic only — nothing you enter is stored or sent anywhere, and the result is not medical advice. Always confirm your dose with your prescriber.