PT-141 Dosage Calculator
Work out your PT-141 dose in seconds.
This PT-141 dosage calculator turns your vial size, water and dose into the exact number of units to draw on an insulin syringe. It opens on a 10 mg vial with 2 mL of bacteriostatic water and the 1.75 mg dose: 35 units. Change any number and the answer updates.
How many units do I draw for PT-141?
If you have a 10 mg vial of PT-141 and want to inject 1.75 mg per injection, you would add 2 mL of water to your vial and draw to 35 units. 35 units equals 0.35 mL on your syringe. This calculation is based off using a 0.5 mL syringe, and every unit you draw has 50 mcg of peptide in it.
If you would also like to know when to inject, how long the vial lasts, if you want to run another peptide at the same time, or how much this will cost,plan it out below
Step 1: Tell the calculator about the peptide you are mixing
The amount of peptide in the vial is the starting point for every number that follows.
Is your vial a freeze-dried powder or a liquid?
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mg vs mcg - what's the difference?
Milligrams (mg) and micrograms (mcg) are units of measurement for weight. There are 1,000 micrograms in every milligram. Peptides typically come in vials that are measured in milligrams but are injected in doses measured in micrograms. For example, if you have a 5mg vial of BPC-157 and your dose is 250mcg, you would first need to convert the 5mg into micrograms which equals 5,000mcg. If you ever input a number into the calculator and it seems 1,000 times too big or too small, you're probably using the wrong unit of measurement. Don't worry, the calculator will recognize this and allow you to fix it with one tap.
Do you have a pre-mixed or compounded vial?
If you have purchased a compounded version of semaglutide or tirzepatide from a compounding pharmacy or if your supplier offers a pre-mixed version of these peptides, you can use this option. These vials already have the peptide mixed in them, so there is no need for you to mix anything.
If your peptide is already liquid, select "Liquid (already mixed)" above and enter how many mg/mL it is. This should be on the label. If you only know the total mg and total mL of the liquid, divide total mg by total mL to get your mg/mL (e.g., 10mg/2mL = 5mg/mL). The calculator will skip the water step for you and go straight to the units, as you do not need to add water. Store the peptide as directed by your pharmacy, as they will likely have different discard instructions than those shown here.
Step 2: Determine How Much Water You Want To Use
Water sets the concentration, and concentration decides how far you pull the plunger.
For this peptide, it is recommended you add 2 mL of water to the vial, as this is how much most people add. This will give you a concentration of 5 mg/mL and make it easy to measure out your dose of 1.75 mg (35 units on a 0.5 mL insulin syringe).
Compare volumes and choose the water
Preserved; use within 4 weeks when stored in the refrigerator.
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Want To Know Why You Can Use Different Amounts Of Water?
No matter how much water you add, the amount of peptide in the vial stays the same. Adding water simply changes the concentration of the peptide and therefore, how much you have to draw up for your dose. Let's say you have a vial of peptide with 5mg of peptide in it and your dose is 250mcg. If you add 1 mL of water, you will have a concentration of 5mg/mL and will need to draw up 5 units on your syringe. However, if you add 2 mL of water, you will have a concentration of 2.5mg/mL and need to draw up 10 units on your syringe to get your 250mcg dose. Depending on your dose, you may find it easier to draw up your dose with less water in the vial (larger doses) or more water in the vial (smaller doses).
How much liquid a vial can take
Most peptides come in small glass vials that hold 3ml. Some hold 2ml. The powder in the vial takes up very little room. You can put 2.5ml to 3ml of water in a 3ml vial and it will fill it to the top of the stopper. If the calculator says to add more water than your vial can hold, get a smaller, thinner syringe instead. The smallest one, the 0.3ml one, has the biggest space in between the ticks. Also, you can get smaller vials. Don't try to put more liquid in the vial than it can hold, it will just shoot back out around the needle.
Why use Bacteriostatic Water?
Bacteriostatic water is just regular sterile water with 0.9% benzyl alcohol in it. This prevents bacteria from growing in your vial, thus allowing you to use the same vial for roughly 4 weeks. Sterile water can be used to mix your peptides if you want, it works just as well, but you can only use it for a day as it doesn't have anything in it to stop bacteria from growing.
How to mix your peptide vial:
- Get everything you need out. Make sure to wash your hands. You will need the vial of peptide, a vial of bacteriostatic water, a syringe to mix the peptide with (doesn't have to be an insulin syringe, a regular 1ml or 3ml syringe works well), alcohol swabs, and some insulin syringes.
- Pop the caps off of your vials and swipe the tops with an alcohol swab. Let them dry for roughly 10 seconds.
- Pull up the amount of water you need to add (from Step 2 of the calculator) into your mixing syringe. Tap it to get any bubbles out.
- SLOWLY add the water to the peptide vial. Don't squirt it directly on the powder or it will foam up, run it along the side of the glass.
- Roll the vial between your hands until the powder is dissolved. Don't shake it, just roll it gently. If there are a few spots of powder left, put it in the fridge for a minute and roll it again.
- Write the date on the vial and stand it upright in the fridge. Your discard date is on the dose card.
Step 3: What is your dose?
The dose turns concentration into a number of units you can read straight off the syringe.
Usual range: 500 mcg to 1.75 mg
1.75 mg as needed
- Usual range
- 500 mcg to 1.75 mg
Used as needed, not cycled
The most common peptide syringe. Easy to read up to 50 units.
Dose by body weight and syringe help
A set amount per injection, in mcg or mg.
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Reading units on a U-100 syringe
A U-100 insulin syringe is marked in units. 100 units is 1 mL, so 1 unit is 0.01 mL.
The calculator converts your dose straight into units, so you read the answer off the barrel with no math.
Pull the plunger until the top of the black rubber stopper lines up with the tick. On a 1 mL barrel the small ticks are 2 units apart. On a 0.5 mL barrel they are 1 unit apart. On a 0.3 mL barrel they are 1 unit, sometimes half a unit.
Which syringe to use
All three barrels are U-100 insulin syringes. Only the size changes.
1 mL (100 units) fits the biggest draws. 0.5 mL (50 units) is the most common for peptides and easy to read. 0.3 mL (30 units) has the widest tick spacing, best when your draw is under about 10 units.
A 29 to 31 gauge needle, 5/16 to 1/2 inch long, suits injections under the skin. The calculator warns you if a draw will not fit, or is too small to read, on the barrel you picked.
Check the syringe says U-100, not U-40
U-40 syringes exist for pet insulin. They have 40 units per mL, not 100.
Every number in this calculator assumes U-100. Draw a U-100 unit count on a U-40 syringe and you inject two and a half times the liquid.
Look for "U-100" printed on the barrel or the box. If it says U-40, do not use these numbers.
Dosing by body weight
Some peptides are dosed per kilogram. Multiply your weight in kg by the mcg/kg figure to get the dose per injection.
80 kg at 5 mcg/kg is 400 mcg. If you weigh in pounds, divide by 2.2 first: 176 lb is 80 kg.
Enter your weight and the mcg/kg and the calculator does this for you, then converts the result into units.
PT-141 Units Chart by Vial Size
Units to draw for common PT-141 doses, worked out from the same numbers the calculator uses. The highlighted card is the mix the calculator opens on.
10 mg vial + 2 mL water
5 mg/mL · the calculator default
- 500 mcg
- 10 units (0.1 mL)
- 1 mg
- 20 units (0.2 mL)
- 1.75 mg
- 35 units (0.35 mL)
5 mg vial + 1 mL water
5 mg/mL
- 500 mcg
- 10 units (0.1 mL)
- 1 mg
- 20 units (0.2 mL)
- 1.75 mg
- 35 units (0.35 mL)
20 mg vial + 4 mL water
5 mg/mL
- 500 mcg
- 10 units (0.1 mL)
- 1 mg
- 20 units (0.2 mL)
- 1.75 mg
- 35 units (0.35 mL)
On a U-100 insulin syringe, 100 units is 1 mL. Units = dose in mg ÷ mg per mL × 100.
PT-141 Dose Range and How Often
PT-141 is bremelanotide. The approved version, Vyleesi, is a single 1.75 mg injection under the skin of the stomach or thigh, at least 45 minutes before sex.
Most people use between 500 mcg and 1.75 mg. A lower first dose is common because nausea is the side effect that puts people off. The label limits use to one dose in 24 hours and eight a month.
For more on how it works and what the trials found, read the PT-141 peptide guide.
How Much Water to Add to PT-141
Add 2 mL of bacteriostatic water to a 10 mg vial. That makes 5 mg/mL, and the 1.75 mg dose lands on 35 units.
The water only changes how big the draw is, not how much drug you get. Less water means fewer units for the same dose and a smaller shot. More water spreads the dose over more ticks, which is easier to measure for small doses like 500 mcg.
Because PT-141 is used now and then, vial life matters. A mixed vial keeps about 30 days in the fridge. If you only use it once or twice a month, a 5 mg vial with 1 mL of water wastes less. If you still need a vial, see PT-141 for sale.
Worked Example in Units
You have a 10 mg vial and add 2 mL of water. Each mL now holds 5 mg/mL.
For 1.75 mg: 1.75 mg ÷ 5 mg/mL = 0.35 mL. On a U-100 syringe that is 35 units. For 1 mg it is 20 units.
The vial gives 5 full doses at 1.75 mg. To run the same sums for any other peptide, use the main peptide calculator.
PT-141 Dosage FAQ
How many units is 1.75 mg of PT-141?
With a 10 mg vial mixed with 2 mL of bacteriostatic water, each mL holds 5 mg/mL, so 1.75 mg is 0.35 mL, or 35 units on a U-100 insulin syringe. A 500 mcg starting dose from the same vial is 10 units.
How much bacteriostatic water do I add to a 10 mg PT-141 vial?
2 mL is the usual choice. It gives 5 mg/mL and puts the 1.75 mg dose at 35 units, which is easy to read on a 0.5 mL syringe. With half the water the same dose is 17.5 units: a smaller shot, but each tick carries twice the drug.
How long before sex should I inject PT-141?
At least 45 minutes. That is the timing on the label of Vyleesi, the FDA-approved form of PT-141 (bremelanotide). Many people inject one to two hours ahead, and the effect can last several hours.
How often can I take PT-141?
No more than one dose in 24 hours, and no more than eight doses a month. Those limits come from the Vyleesi label. PT-141 is used as needed, not on a daily schedule.
How many doses are in a 10 mg vial of PT-141?
5 full doses at 1.75 mg, 10 at 1 mg, or 20 at 500 mcg. Once mixed, the calculator assumes the vial keeps about 30 days in the fridge, so with occasional use some of a large vial can go to waste.
What are the side effects of PT-141 at 1.75 mg?
Nausea is the big one: about 4 in 10 people had it in the Vyleesi trials, usually after the first dose. Flushing and headache are also common. Blood pressure rises for a few hours after each dose, so it is not for anyone with uncontrolled high blood pressure or heart disease. Starting at a lower dose is a common way to test how you react.
All tools are for educational purposes only, not medical advice.