Peptide Unit Converter
Convert between mcg, mg, and IU for any peptide with built-in conversion factors for common compounds.
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Understanding Peptide Units
Peptide dosing involves three main units of measurement: micrograms (mcg), milligrams (mg), and International Units (IU). Micrograms and milligrams are straightforward metric units of mass where 1 mg equals 1,000 mcg. Most research peptides like BPC-157, TB-500, and CJC-1295 are dosed in mcg or mg because their effects are directly proportional to the amount of substance administered.
International Units (IU) are different. Rather than measuring weight, IU measures the biological activity of a substance. This means the conversion from mg to IU is unique to each peptide. For example, 1 mg of HGH equals approximately 3 IU, while 1 mg of insulin equals approximately 27.5 IU. The IU value is established by international reference standards that define how much of a substance produces a specific biological effect.
A common source of confusion is assuming that IU is a universal unit. In reality, 1 IU of HGH and 1 IU of insulin represent completely different masses. This is why you should never convert between IU values of different peptides without knowing each peptide's specific conversion factor. When in doubt, always check the manufacturer's documentation for the exact IU-to-mg ratio of your specific product. Pair this tool with the cost calculator to verify how many doses each vial provides, or see our getting started guide for reconstitution and syringe math basics.
Common Conversion Reference
How to Use This Converter
- 1.Choose your conversion type. Select "mcg ↔ mg" for simple metric conversions, or "mg ↔ IU" if you need to convert between mass and biological activity units.
- 2.For IU conversions, select the peptide you are working with. Each peptide has a different IU-per-mg factor. If your peptide is not listed, choose "Custom" and enter the conversion factor from your product documentation.
- 3.Enter the value you want to convert and select whether it is in the source unit (e.g., mcg or mg). The converter will calculate the equivalent in the target unit.
- 4.Click "Convert" to see your result along with the conversion factor used. For IU conversions, the result includes which peptide factor was applied.
Frequently Asked Questions
What is an International Unit (IU)?
An International Unit (IU) is a standardized measurement used to quantify the biological activity of a substance, not its weight. Because different substances have different potencies per milligram, the IU provides a way to compare doses based on actual effect rather than mass. For example, 1 IU of HGH represents a different weight than 1 IU of insulin, because each peptide has a different biological potency per milligram.
Why does the IU value differ between peptides?
Each peptide has a unique molecular structure and biological potency. The IU-to-mg conversion factor is determined by international reference standards that measure how much of a substance is needed to produce a specific biological effect. For instance, HGH has about 3 IU per mg because it takes roughly 0.33 mg to produce one international unit of growth hormone activity, while insulin has about 27.5 IU per mg because it is far more potent per milligram.
What is the difference between mcg and mg?
Both are metric units of mass. One milligram (mg) equals 1,000 micrograms (mcg). Peptide doses are often expressed in mcg for smaller amounts (like BPC-157 at 250 mcg) and in mg for larger amounts (like TB-500 at 2.5 mg). Converting between them is straightforward: multiply mg by 1,000 to get mcg, or divide mcg by 1,000 to get mg.
How do I convert syringe units to mcg?
Syringe units on an insulin syringe measure volume, not weight. On a standard U-100 syringe, 100 units equals 1 ml. To convert syringe units to mcg, you need to know the concentration of your reconstituted solution. For example, if you dissolved 5 mg (5,000 mcg) of peptide in 2 ml of bacteriostatic water, the concentration is 2,500 mcg per ml. Each syringe unit (0.01 ml) would then contain 25 mcg. Use our Reconstitution Calculator for this math.
What units are most common for peptide dosing?
Most research peptides like BPC-157, TB-500, and CJC-1295 are dosed in mcg or mg. Hormones and hormone-like peptides such as HGH, insulin, and HCG are typically dosed in IU because their biological activity is what matters clinically. When purchasing peptides, the vial label usually shows the total content in mg, while dosing protocols are written in either mcg, mg, or IU depending on the peptide.
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