How many units of testosterone is 100 mg?

It depends on the vial concentration. On a U-100 insulin syringe, 1 mL = 100 units. At 200 mg/mL, 100 mg is 0.5 mL = 50 units; at 100 mg/mL, 100 mg is 1 mL = 100 units. Enter your concentration above to get the exact number.

How do I split a weekly testosterone dose?

Divide the weekly dose by the number of injections per week. More frequent, smaller injections (twice weekly, every other day, or daily) produce steadier blood levels than one large weekly shot. This calculator does the split for you.

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TRT dose calculator

Turn your weekly testosterone dose into the exact mL and insulin-syringe units to draw per injection — and see how long a vial will last.

By OptiPin Editorial·Last updated June 6, 2026

Weekly dose (mg)

Vial concentration (mg/mL)

Injections per week

Vial size (mL, optional)

Enter your values above

Fill in your weekly dose and vial concentration to see units, volume, and per-injection dose.

Educational use only. This calculator is for informational purposes and does not constitute medical advice or a dosing recommendation. Always follow your prescriber's instructions and verify your dose. Insulin-unit results assume a U-100 syringe (1 mL = 100 units). Measurement errors can have serious health consequences — double-check your calculations.

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Track every injection in the OptiPin app

Log doses, rotate injection sites, forecast testosterone & estrogen levels, track inventory, and get smart reminders — all on-device, no cloud required.

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How to use this calculator

Enter your weekly dose

The total testosterone (mg) your protocol calls for each week.

Enter the concentration

Printed on the vial, e.g. 200 mg/mL. Tap a preset for common strengths.

Pick your frequency

More frequent, smaller injections give steadier levels. The weekly dose is split for you.

Draw to the units shown

On a U-100 insulin syringe, draw to the unit mark shown. Optionally add your vial size to see how long it lasts.