Enter a weekly target or mL per injection
Choose the input mode. Your numbers and selected mode remain unchanged when you switch language.
How TRT Dose Calculator Works
A clear guide to the inputs, formulas, and rounding so you know exactly what the calculator calculates.
Short answer
What does the TRT calculator do?
It converts either a weekly target in mg or an entered volume in mL into mg and mL per injection, U-100 markings, and an average weekly value based on frequency. It is an arithmetic education tool, not a dose or schedule recommendation.
Enter the concentration
Use the value printed on the vial label in mg/mL, for example 250 mg/mL.
Choose the frequency
Frequency determines the number of injections used in the weekly calculation; the calculator does not recommend a frequency.
Read mg, mL, and U-100 units
You get mg and mL per injection, U-100 markings, an average weekly value, a schedule, and estimated vial usage.
Worked example
200 mg/week at 250 mg/mL, every day
You enter
- Weekly target
- 200 mg
- Concentration
- 250 mg/mL
- Frequency
- Every day
- Injections per week
- 7
You get
- mg per injection
- ≈28.57 mg
- Exact volume
- ≈0.1142857 mL
- Calculation and schedule precision
- 0.1142857… mL
- Compact result card
- 0.11 mL
- If 0.11 mL is actually used daily
- 192.5 mg/week
- U-100 scale
- ≈11.4 units
- Weekly volume
- 0.8 mL
The calculation is 200 ÷ 7 = 28.5714 mg per injection; 28.5714 ÷ 250 = 0.1142857 mL; 0.1142857 × 100 = 11.4286 U-100 units. The calculator and schedule data use the full internal value; calendar text displays 0.114 mL, while the compact result card displays 0.11 mL. Actually administering 0.11 mL daily at 250 mg/mL equals 27.5 mg per injection and 192.5 mg/week, not 200 mg/week. Display rounding is not a dosing recommendation; practical rounding to syringe markings must be confirmed with a licensed medical professional.
Formulas used
All calculations run locally in the browser. Changing language changes the text, not the numerical precision.
1. Doses per week
doses_per_week = 7 / interval_days
2. mg per injection
mg_per_injection = weekly_mg / doses_per_week
3. mL per injection
mL_per_injection = mg_per_injection / concentration_mg_per_mL
4. Weekly mL
weekly_mL = weekly_mg / concentration_mg_per_mL
5. U-100 units
units_per_injection = mL_per_injection × 100
6. Complete injections from a vial
complete_injections = floor(vial_volume_mL / mL_per_injection)
7. Remaining vial volume
remaining_mL = vial_volume_mL − (complete_injections × mL_per_injection)
8. Estimated days of supply
interval_days = 7 / injections_per_week; days_of_supply = complete_injections × interval_days
Vial usage is an estimate. The implementation counts only complete injections with floor, calculates the volume remaining after them, and multiplies their number by the interval between injections. The interface rounds estimated days to the nearest whole day and displays a remainder of up to 0.01 mL as 0 mL. The estimate does not account for draw loss, dead space, or measurement error.
Precision and limitations
What is the difference between exact and rounded values?
- Exact calculated value
- The calculator retains the full value for subsequent calculations. In the example it is approximately 0.1142857 mL.
- Displayed value
- The card shows a compact 0.11 mL, the detail line shows 0.1143 mL, and the calendar shows 0.114 mL. Calculations and schedule events use the unrounded internal value. Actually administering 0.11 mL daily at 250 mg/mL gives 192.5 mg/week, so display rounding must not be treated as a dose recommendation.
- U-100 units
- U-100 denotes a scale of 100 units per 1 mL, so 1 unit on that scale equals 0.01 mL.
- Not a practical instruction
- The calculator does not determine which marking, syringe, dose, or frequency is appropriate. Verify the label, device, and prescription with a licensed medical professional.
Method and sources
How is the logic checked?
The formulas are direct conversions between mg, mg/mL, and mL. The worked example above can be calculated by hand and serves as a check of the output. The calculator does not interpret laboratory results or suggest treatment.
- DailyMed: official labeling that defines U-100 as 100 units/mL
- CDC: general information on safe injection practices
- Full medical disclaimer and calculator limitations
Methodology last updated: July 30, 2026.
Educational use only - not medical advice. Verify every dose with a licensed clinician. Read the full disclaimer.
