Skip to main content

TRT Dosage Calculator

Educational tool that converts a weekly TRT target (mg/week) and vial concentration (mg/mL) into per-injection volumes for several common frequency patterns. The ester selector drives the optional blood-levels chart's terminal half-life; it does not change the per-injection mg/mL math.

New here? See a worked example

Enter your weekly target and vial concentration to start.

Quick start

Load a common protocol to fill the form in one click.

No result yet - enter a weekly dose and vial concentration above to see your live result here.

How it works

Three short steps. The math is purely arithmetic - it does not model ester half-life, peak/trough behaviour, or any patient-specific factor. Use it to sanity-check the volume your prescription works out to.

  1. Enter your weekly testosterone target

    Type your weekly target in milligrams - for example, 100 mg/week as a common starting target, or 200 mg/week for a higher maintenance dose.

  2. Enter the vial concentration

    Read the concentration off the vial label in mg/mL (commonly 100 mg/mL or 200 mg/mL for cypionate or enanthate) and type it in.

  3. Pick your injection frequency

    Choose how often you inject - weekly, twice weekly, every other day, daily, or a custom interval. The calculator splits the weekly target across those injections.

  4. Read mg, mL, and U-100 syringe units per injection

    You get milligrams per injection, the volume in mL to draw, the matching marking on a U-100 insulin syringe, and how long the vial will last at that schedule.

Worked example

100 mg/week testosterone cypionate at 200 mg/mL, split twice weekly

You enter
Weekly target
100 mg
Concentration
200 mg/mL
Frequency
Twice weekly
Vial size
10 mL
You get
mg per injection
50 mg
Volume per injection
0.25 mL
U-100 syringe units
25 units
Doses per vial
40 doses
Days of supply
140 days

Each injection is 0.25 mL - the 25-unit mark on a U-100 insulin syringe - taken twice a week. A 10 mL vial covers about 20 weeks at this schedule.

Show the underlying formulas

  1. 1. Doses per week

    doses_per_week = 7 / interval_days

  2. 2. Mg per injection

    mg_per_injection = weekly_mg / doses_per_week

  3. 3. mL per injection

    mL_per_injection = mg_per_injection / concentration_mg_per_mL

  4. 4. Weekly mL

    weekly_mL = weekly_mg / concentration_mg_per_mL

  5. 5. U-100 syringe units (estimate)

    units_per_injection = mL_per_injection * 100

  6. 6. Vial volume (mL)

    vial_volume_mL = vialSize (when unit = mL) OR vialSize / concentration_mg_per_mL (when unit = mg)

  7. 7. Doses per vial

    doses_per_vial = floor(vial_volume_mL / mL_per_injection)

  8. 8. Days of supply

    days_of_supply = doses_per_vial * interval_days

Full citations and assumptions: see methodology page.

Frequently asked questions

What does the TRT dosing calculator do?
It splits a weekly testosterone target (in mg/week) and a vial concentration (in mg/mL) into milligrams and millilitres per injection across common frequency patterns - weekly, twice weekly, every other day, daily, or a custom interval. It also estimates U-100 syringe units, full doses per vial, and days of supply.
How many mL is 200 mg of testosterone cypionate at 200 mg/mL?
1 mL. The math is mg divided by mg/mL: 200 / 200 = 1 mL. On a U-100 insulin syringe that's 100 units. The calculator runs the same conversion automatically once you enter your weekly target and vial concentration.
Does the ester (cypionate, enanthate, propionate) change the math?
No - the ester selector in the calculator is informational only. The arithmetic for mg-per-injection and mL-per-injection is identical regardless of ester. What does change between esters is half-life, peak/trough behaviour, and how often most clinicians will recommend you inject; this calculator does not model any of those.
Should I split my weekly TRT dose or do one weekly injection?
That's a clinical decision, not a math one. Splitting (e.g. twice weekly or every other day) tends to flatten serum testosterone peaks and troughs, which some clinicians prefer for shorter-acting esters like cypionate or enanthate. The calculator will divide your weekly target across whatever frequency you choose so you can compare per-injection volumes side by side.
How do I read U-100 syringe markings for TRT?
U-100 insulin syringes use a 100 units = 1 mL scale (1 unit = 0.01 mL). The calculator multiplies your draw volume by 100 to give you the unit marking - so a 0.5 mL injection is 50 units. Confirm the markings on your specific syringe before drawing.
Why does the doses-per-vial number round down?
A partial last dose isn't a useful planning unit, so the calculator floors the count and reports the leftover volume separately. Days of supply only count whole injections so it never overstates how long a vial will last.
Does this calculator model peak and trough hormone levels?
No. It is purely an arithmetic conversion tool: weekly mg divided by doses per week, then divided by mg/mL. It does not model PK, ester half-life, body composition, sex-hormone-binding globulin, or any patient-specific variable. Always work with a licensed clinician for protocol decisions.
Is this calculator appropriate for HRT for women?
The same arithmetic applies - mg divided by mg/mL gives you mL - so the conversion math is valid. However, female TRT/HRT protocols use much lower doses and different vial concentrations, so always work with a clinician who specialises in female hormone therapy and confirm every number against your prescription.