How to Use the TRT Dose Calculator
This calculator converts your prescribed testosterone dose (in milligrams) into the exact injection volume (in milliliters) based on your vial concentration. It also helps you split your weekly dose across multiple injections and estimate how long a vial will last.
What You Need
- Your prescribed weekly dose (e.g., 150mg/week)
- Your vial concentration (e.g., 200mg/mL)
- Your injection frequency (e.g., twice per week)
The Basic Formula
Injection Volume (mL) = Prescribed Dose (mg) ÷ Vial Concentration (mg/mL)
Example: 150mg prescribed ÷ 200mg/mL concentration = 0.75 mL per week
If injecting twice weekly: 0.75 mL ÷ 2 = 0.375 mL per injection
Common TRT Concentrations
| Testosterone Ester | Common Concentrations | Notes |
|---|---|---|
| Testosterone Cypionate | 200mg/mL | Most common in US |
| Testosterone Cypionate | 100mg/mL | Used when lower volumes are impractical |
| Testosterone Enanthate | 250mg/mL | Common internationally |
| Testosterone Enanthate | 200mg/mL | Common in US |
| Testosterone Propionate | 100mg/mL | Short-acting, less common for TRT |
Why Injection Frequency Matters
Traditional TRT protocols prescribe a single weekly injection (or even every two weeks). However, more frequent dosing produces more stable blood levels and typically reduces side effects.
Injection Frequency Comparison
| Frequency | Pros | Cons |
|---|---|---|
| Every 2 weeks | Fewer injections | Large peaks and troughs, more side effects, more estrogen conversion |
| Once weekly | Convenient | Moderate peak-trough variation |
| Twice weekly | Stable levels, reduced E2 conversion | More injections |
| Every other day (EOD) | Most stable levels | Most injections, requires commitment |
| Daily (subcutaneous) | Extremely stable, mimics natural production | Daily commitment, very small volumes |
Most modern TRT-prescribing physicians recommend at minimum twice-weekly injections for optimal results and fewer side effects.
Estimating Vial Duration
Standard testosterone vials come in 1 mL and 10 mL sizes:
| Vial Size | Concentration | Weekly Dose | Vial Duration |
|---|---|---|---|
| 1 mL | 200mg/mL | 100mg | ~2 weeks |
| 1 mL | 200mg/mL | 150mg | ~1.3 weeks |
| 1 mL | 200mg/mL | 200mg | 1 week |
| 10 mL | 200mg/mL | 100mg | ~20 weeks |
| 10 mL | 200mg/mL | 150mg | ~13 weeks |
| 10 mL | 200mg/mL | 200mg | 10 weeks |
Note: Multi-use vials (10 mL) should be discarded 28 days after first puncture per USP guidelines, though many patients and clinicians use them longer when stored properly.
Subcutaneous vs. Intramuscular Injection
| Factor | Subcutaneous (SubQ) | Intramuscular (IM) |
|---|---|---|
| Needle size | 27-30 gauge, 0.5 inch | 22-25 gauge, 1-1.5 inch |
| Injection sites | Abdomen, thigh, love handles | Glute, vastus lateralis, deltoid |
| Pain | Minimal | Mild to moderate |
| Absorption | Slower, more sustained | Faster peak |
| Max volume per site | ~0.5 mL | 1-3 mL |
| Best for | Frequent small doses | Larger, less frequent doses |
SubQ injection has gained popularity for TRT because it allows smaller needles, less pain, and more stable absorption. It is particularly well-suited for twice-weekly or daily micro-dosing protocols.
Important Safety Notes
- This calculator is for educational purposes. Always follow your prescribing physician's dosing instructions.
- Never adjust your dose without consulting your doctor. Dose changes should be guided by blood work (total testosterone, free testosterone, estradiol, hematocrit).
- Use proper injection technique including alcohol swabbing, proper needle gauge, and rotating injection sites.
- Monitor blood work at 6-8 weeks after starting TRT and every 3-6 months thereafter. Key markers include total testosterone, free testosterone, estradiol (sensitive), hematocrit, PSA, and lipid panel.
- Store testosterone at room temperature, away from light. Do not freeze.
When to Adjust Your Protocol
Signs your dose or frequency may need adjustment:
- Dose too high: Acne, elevated hematocrit (above 54%), mood instability, elevated estradiol, sleep disruption
- Dose too low: Persistent fatigue, low libido, poor recovery, blood levels below optimal range
- Frequency too low: Energy and mood dips before next injection, elevated estradiol from large peaks
Work with your prescribing physician to optimize your protocol based on both blood work and symptoms.