What are Steroid Esters? Nick Trigili Breaks Down All You Need to Know!

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Breaking down steroid esters.

An extremely important, yet often forgotten, component of steroid chemistry is the fact that every esterified steroid (steroid with an ester attached) has a certain component of the steroids overall mass consisting of the weight of the ester, not of the hormone. This means that, 100mg of Testosterone Enanthate is not 100mg of pure Testosterone. In fact, you may have been severely under-dosing compared to what you thought you were taking, and once the ester has been removed through the esterase enzyme, the amount of pure hormone testosterone left over is very different than what you thought you were administering.

Long chain esters, such as Cypionate, Decanoate, Enanthate, etc. possess a significantly greater molecular weight than short chain esters. Consequently, on a mg per mg basis, you are receiving far more unesterified steroid in a short estered compound compared to a large estered compound. 100mg of Testosterone Propionate is not equivalent to 100mg of Testosterone Enanthate, contrary to common belief. This is due to the shorter, and consequently lighter weight of the propionate ester relative to the larger and heavier enanthate ester. Mindful bodybuilders should always consider this factor as one of the various elements that determine their choice of AAS type or dosage. Esters are an essential component of how steroid hormones are metabolized and should be common knowledge for anyone taking AAS.

In order to more appropriately convey the massive differences in the quantity of raw hormone in a given dosage depending on ester, here is a list of some of the most common esterified injectable compounds and how much free hormone is left in a given amount of the compound (standardized to 100mg),


\100mg Testosterone Suspension (un-esterified Testosterone) = 100mg Testosterone

100mg Testosterone Acetate = 83mg Testosterone

100mg Testosterone Propionate = 80mg Testosterone

100mg Testosterone Isocaproate = 72mg Testosterone

100mg Testosterone Enanthate = 70mg Testosterone

100mg Testosterone Cypionate = 69mg Testosterone

100mg Testosterone Phenylpropionate = 66mg Testosterone

100mg Testosterone Decanoate = 62mg Testosterone

100mg Testosterone Undecanoate = 61mg Testosterone

100mg Trenbolone Acetate = 87mg Trenbolone

100mg Trenbolone Enanthate = 70mg Trenbolone

100mg Trenbolone Hexahydrobenzylcarbonate = 70mg Trenbolone


100mg Nandrolone Phenylpropionate = 67mg Nandrolone

100mg Nandrolone Decanoate = 64mg Nandrolone


100mg Drostanolone Propionate = 80mg Drostanolone

100mg Drostanolone Enanthate = 70mg Drostanolone


Now that I have given you a basic background on what steroid esters are and what they do, I can give you specifics about how to apply this to your career, your recycle plant, and finding the amount of pure hormone you’re ultimately going to want/need.

If you wish to find out the amount of pure steroid in a specific amount of esterified hormone, the steps are simple. Let’s take Primobolan (Methenolone Enanthate) as an example. We want to figure out how much free Methenolone exists in 750mg of Methenolone Enanthate (Primobolan).

First we must find out the molecular weight of Methenolone itself (In its unesterified and pure form; this is very important): 302.45 g/mol

We must then calculate the molecular weight of the Enanthate ester (when unattached to any molecules, it is technically referred to as heptanoic or enanthic acid): 130.18 g/mol

The two weights must then be added in order to determine the total weight of Methenolone Enanthate: 302.45 + 130.18 = 432.63 g/mol

The total weight must then be divided by the weight of the ester in order to find out what  percentage of the compound’s total weight is occupied by the Enanthate ester: 432.63 / 130.18 = 3.32

This number is our percentage; we multiply it by 10 to obtain the proper value. We get a total of 33% (rounded off).

33% of the Methenolone Enanthate molecule is occupied by the Enanthate ester. We wanted to know how much pure and free Methenolone is left over in 750mg of Primobolan Enanthate. This is a two-step process, so we must subtract 33% from 750mg: 750 x 0.33 = 247.5mg

247.5mg is how much weight the Enanthate ester comprises the 750mg total of Primobolan. If we subtract that number from 750, we get: 502.5mg of un-esterified free Methenolone left over from 750mg of Methenolone Enanthate (Primobolan).

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Nick Trigili is a respected IFBB Pro bodybuilder and trainer. Check him out on Instagram, Twitter, and Facebook for more informative content. Also make sure to visit his official personal training website – World Class Trainers.

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