TRT Injection Calculator
Convert your weekly mg, vial concentration, and injection frequency into exact insulin syringe units. Works for daily microdosing, every-other-day, twice-weekly, and weekly protocols.
Injection volume
Concentration and dose to mL and insulin-syringe units.
Enter your weekly dose to calculate how much to draw per injection.
Inject every 3-4 days (e.g., Monday & Thursday)
Draw syringe to
38 units
(0.38 mL)
This calculator is for informational purposes only, so always double-check your result with a healthcare provider. We assume no liability for dosing errors.
Last updated September 2026 · Reviewed by the Regimen Team
The tool
How it works, what it tells you, what it doesn't.
The TRT injection calculator turns your prescription into the exact units to draw. Enter your weekly mg, your vial concentration in mg/mL (200 mg/mL is the US standard for testosterone cypionate), and how often you inject. It divides the weekly dose across your schedule and returns mg, mL, and units on a 100-unit insulin syringe for each shot. Switch between weekly and per-injection modes to plan a protocol or check a single draw.
How to use it
How to use this calculator
- 01
Enter weekly mg
Your full prescribed weekly dose (e.g., 200 mg)
- 02
Enter vial concentration
Standard testosterone cypionate in the US is 200 mg/mL
- 03
Pick a frequency
Daily, every other day, twice weekly, or weekly
- 04
Read the units
Calculator returns exact units on a 100-unit insulin syringe
Worked example: 200 mg/week at 200 mg/mL
The 200 mg per week prescription at a 200 mg per mL vial concentration is the most common TRT setup in the US. The unit math falls cleanly across every standard injection frequency.
- Daily microdose (7x/week): 200 ÷ 7 = 28.6 mg per day. 28.6 ÷ 200 = 0.143 mL. About 14 units per day.
- Every other day (3.5x/week): approximately 57 mg per injection, which is 0.29 mL, or about 29 units.
- Twice weekly (2x/week): 100 mg per injection = 0.5 mL = 50 units.
- Weekly (1x/week): 200 mg = 1.0 mL = 100 units (fills the full barrel of a 100-unit insulin syringe).
The math generalizes to any concentration. If your vial is 100 mg per mL instead of 200, double the mL and unit numbers. If it’s 250 mg per mL, multiply the mL by 0.8.
Why frequency matters more than total dose
With test cypionate’s roughly 6.9-day half-life and test enanthate’s 6.9-day half-life, your injection frequency directly drives how flat your weekly testosterone levels look. Weekly injection produces a noticeable peak-to-trough swing; twice-weekly compresses it; daily microdosing flattens it almost entirely. Flatter levels generally mean less estradiol conversion from peaks, less symptomatic variance, and easier hematocrit management.
Modern TRT clinical practice has moved toward twice-weekly minimum, with daily microdosing becoming common for users who want maximum stability. For the full walkthrough of daily and EOD protocols, including unit rounding for non-round divisions, see the microdosing TRT guide and the insulin syringe daily TRT dose guide.
Get the app
Log every TRT injection with the unit math built in
Regimen has the injection calculator built in and logs each shot with site rotation, dose, and reminders. Free for one compound.
- Built-in dose calculators
- Smart injection reminders
- Symptom and lab correlation
- Private, secure health data
Free to download. Free for your first compound.
Questions