Peptide Calculator
Accurately calculate your dosage for reconstitution with bacteriostatic water.
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* Disclaimer: This calculator is for educational/research purposes. 1 Unit = 0.01mL on a U-100 syringe.
👨🔬
By Prof. David Anderson
Professor of Analytical Chemistry & Toxicology
“I am an academic chemist, not your physician. What you do with your own biology is your choice. However, as a scientist, it absolutely terrifies me to watch thousands of people buy lyophilized peptide powder on the internet and attempt to reconstitute it in their kitchens. If you cannot do basic dimensional analysis—if you do not understand the profound, potentially lethal difference between a milligram (mg) and a microgram (mcg)—you have absolutely no business handling a syringe. Today, I am putting an end to the guessing game. We are going to use our Peptide Calculator to rigorously define volumetric concentration, permanently decode the confusing tick marks on a U-100 syringe, and establish a strictly idiot-proof system for liquid measurement.”
Medical Disclaimer: This page and the associated calculator are provided for mathematical and educational research purposes only. It is strictly NOT medical advice. The calculations provided simply convert mass and volume into theoretical concentrations. Always consult a licensed medical professional before administering any biologically active substance.
The Peptide Reconstitution Calculator & Toxicology Guide
Mastering Volumetric Concentration, U-100 Syringes, and Safe Reconstitution Math
1. The Reconstitution Principle (The Math of the Vial)
Peptides like Semaglutide, Tirzepatide, or BPC-157 are often shipped as a “lyophilized” (freeze-dried) puck of powder at the bottom of a glass vial. Because they are shipped dry to preserve molecular stability, you must dissolve them in a solvent before use.
THE LAW OF CONSERVATION OF MASS
If you have a vial containing exactly 5 mg of peptide powder, and you add 1 mL of water to it, the vial contains 5 mg of peptide.
If you take that identical 5 mg vial, and you add 3 mL of water to it, the vial still contains exactly 5 mg of peptide.
Adding more water does NOT “weaken” or destroy the drug. It simply dilutes the concentration. The amount of water you add is entirely up to you, but it dictates how much physical liquid you must pull into your syringe later to get the desired dose.
If you have a vial containing exactly 5 mg of peptide powder, and you add 1 mL of water to it, the vial contains 5 mg of peptide.
If you take that identical 5 mg vial, and you add 3 mL of water to it, the vial still contains exactly 5 mg of peptide.
Adding more water does NOT “weaken” or destroy the drug. It simply dilutes the concentration. The amount of water you add is entirely up to you, but it dictates how much physical liquid you must pull into your syringe later to get the desired dose.
The fundamental mathematical equation governing this entire process is the Volumetric Concentration Formula:
$$C = \frac{Mass_{peptide}}{Volume_{solvent}}$$
Volumetric Concentration Formula
2. The Solvent: Bacteriostatic vs. Sterile Water
A common mistake beginners make is using the wrong solvent. Bacteriostatic Water (BAC water) is strictly required for multi-dose peptide vials. Why? BAC water contains exactly 0.9% benzyl alcohol. This alcohol acts as a preservative that halts the reproduction of bacteria within the vial.
If you reconstitute a 5 mg vial with plain “Sterile Water” and store it in your fridge to use over four weeks, you are cultivating a bacterial petri dish. Sterile water contains zero preservatives and is intended for immediate, single-use injections only. Always ensure your math accounts for the specific BAC water volume you are injecting.
3. The Ultimate Sin: Confusing mg and mcg
Before we calculate anything, we must address the most dangerous mistake in the biohacking community. Vials are almost always sold in milligrams (mg). However, your desired dosage protocol is very often measured in micrograms (mcg or µg).
🚨 The Fatal 1,000x Error
One milligram (1 mg) is equal to one thousand micrograms (1000 mcg).
If your research protocol calls for a 250 mcg dose, and you look at your calculator and accidentally enter 250 mg, you are attempting to calculate a dose that is one thousand times higher than intended. Always convert your vial’s total mass into the same unit as your target dose before doing the math.
4. The Quick Reference Conversion Cheat Sheet
To prevent lethal decimal point errors, review this strict conversion table before touching your syringe.
| Milligrams (mg) | Micrograms (mcg / µg) | Typical Context |
|---|---|---|
| 0.25 mg | 250 mcg | Common initiation (starting) dose. |
| 0.50 mg | 500 mcg | Common step-up titration dose. |
| 1.00 mg | 1,000 mcg | Standard maintenance dose. |
| 2.40 mg | 2,400 mcg | High-end clinical maximum dose. |
| 5.00 mg | 5,000 mcg | Total mass of a standard lyophilized vial. |
5. Decoding the U-100 Insulin Syringe
You have mixed your vial. Now you are holding a plastic syringe with numbers on the side like 10, 20, 30… up to 100. What do these numbers mean?
The Syringe Translation:
- A standard insulin syringe is specifically calibrated for U-100 insulin.
- A full U-100 syringe holds exactly 1 milliliter (1 mL) of liquid.
- The syringe has 100 little tick marks, called Units.
- Therefore, 100 Units = 1 mL.
- Mathematically: 1 Unit = 0.01 mL.
If your peptide reconstitution calculator states you need to inject 0.15 mL of liquid, you simply pull the plunger down to the 15 Unit mark.
⚠️ The Deadly Mix-Up: U-100 vs U-40 Syringes
Never buy veterinary U-40 syringes for human peptide research. A U-40 syringe is calibrated completely differently (40 units = 1 mL). If you use a U-40 syringe but apply U-100 math from our calculator, you will inject 250% more liquid than intended. Ensure your packaging explicitly states “U-100”.
6. Case Study 1: Reconstituting and Dosing
Let us walk through a complete, rigorous calculation. This is the exact algorithmic path running behind our calculator.
1
The Baseline Dosage Math
You have purchased a 5 mg vial of lyophilized powder. You decide to add 2 mL of bacteriostatic water. Your research protocol requires a target dose of 250 mcg. How many Units should you draw on a U-100 syringe?
Step 1: Unify the Units (Crucial!)
Convert the vial mass from mg to mcg.
5 mg × 1000 = 5000 mcg.
Step 2: Calculate the Concentration ($C$)
$$C = \frac{5000 \text{ mcg}}{2 \text{ mL}} = 2500 \text{ mcg/mL}$$
(This means every 1 mL of liquid contains exactly 2500 mcg of peptide).
Step 3: Calculate the Required Draw Volume ($V_{draw}$)
$$V_{draw} = \frac{Dose_{target}}{C}$$
$$V_{draw} = \frac{250 \text{ mcg}}{2500 \text{ mcg/mL}} = \mathbf{0.1 \text{ mL}}$$
Step 4: Convert mL to Syringe Units
$$Ticks = 0.1 \text{ mL} \times 100 = \mathbf{10 \text{ Units}}$$
Correct Conclusion: To achieve exactly a 250 mcg dose, you must pull the plunger of the U-100 syringe to the ’10’ tick mark.
7. Case Study 2: The “Too Little Liquid” Problem
Why do we sometimes add more water? Let us look at what happens if we use too little solvent for a highly concentrated target dose.
2
The Micro-Dose Dilemma
You have a massive 10 mg vial. You add only 1 mL of BAC water. You want a tiny dose of 250 mcg.
Step 1: Concentration
10,000 mcg / 1 mL = 10,000 mcg/mL.
Step 2: Draw Volume
250 mcg / 10,000 mcg/mL = 0.025 mL.
Step 3: Syringe Units
0.025 mL × 100 = 2.5 Units.
Conclusion: You must pull to exactly two-and-a-half tiny tick marks. This is incredibly difficult to measure by eye, and a microscopic slip of the thumb means you accidentally doubled your dose! This is why scientists purposefully add MORE water (e.g., 3 mL) to “dilute” the liquid, forcing a larger, much easier-to-measure volume (like 15 Units) on the syringe to get the exact same drug dose.
8. Case Study 3: The Titration Protocol (Scaling the Dose)
Clinical protocols often require “titration”—starting at a low dose to assess tolerance, and then increasing it over weeks. How does the math change if the vial remains the same?
3
The Weekly Step-Up Math
Continuing from Case Study 1 (5 mg vial, 2 mL water, Concentration = 2500 mcg/mL). You have completed 4 weeks at 250 mcg (10 Units). Now, your protocol dictates you must step up your dose to 500 mcg (0.5 mg).
The Fast Calculation:
Because your vial’s concentration ($C$) is locked in and unchanged, the relationship between dosage and volume is perfectly linear. If you double your required dose, you simply double your drawn volume.
$$V_{draw} = \frac{500 \text{ mcg}}{2500 \text{ mcg/mL}} = \mathbf{0.2 \text{ mL}}$$
$$Ticks = 0.2 \text{ mL} \times 100 = \mathbf{20 \text{ Units}}$$
Conclusion: To inject 500 mcg from this specific vial, you pull the plunger to the ’20’ tick mark. Always recalculate if you mix a brand new vial with a different amount of BAC water!
9. Professor’s FAQ Corner
Q: Does the calculation change if I am using a 0.3mL or 0.5mL syringe?
No. As long as the syringe is explicitly labeled as a U-100 syringe, the physical spacing and definition of the units remain mathematically identical. A 0.5mL syringe just physically stops at 50 Units instead of 100. A 10 Unit draw on a 0.5mL syringe contains the exact same volume of liquid (0.1 mL) as a 10 Unit draw on a 1.0mL syringe.
Q: What is syringe “dead space” and should I account for it?
Dead space is the tiny amount of liquid trapped in the needle tip and hub after the plunger is fully depressed. In standard U-100 insulin syringes with fixed (non-removable) needles, this space is negligible and does not affect your dose. However, if you are using Luer-lock syringes with detachable needles, dead space can waste up to 0.05 mL of expensive liquid per draw. You do not change your calculator math for this, but you will notice the vial empties faster than calculated.
Q: How long does a reconstituted peptide last?
Once a lyophilized peptide is mixed with Bacteriostatic Water, the fragile peptide bonds begin to slowly degrade. While timelines vary by specific compound, the general scientific consensus is that reconstituted vials should be kept refrigerated (between 2°C and 8°C) and used within 28 days. After this point, efficacy degrades and the bacteriostatic agent loses its protective potency.
Stop Guessing. Calculate Your Exact Dosage.
Never rely on forum posts, Reddit comments, or mental math when handling potent biological compounds. Use our Peptide Calculator to lock in your vial mass, input your bacteriostatic water volume, and instantly generate the exact “Tick Mark” (Unit) reading required for your specific U-100 syringe.
Open the Peptide Reconstitution Calculator