By Austin Witherow and Mason Calvert · Last updated · Sources
What an ester is
An injectable steroid ester is the hormone with a fatty acid chain bonded to it. In oil, the chain slows how fast the hormone leaves the injection site. Once in the blood, the chain is cut off and the hormone is what remains active.
The chain has weight. A vial labelled in milligrams of the ester counts that weight, so 100 mg of an ester is less than 100 mg of the hormone. The longer the chain, the bigger the gap.
The arithmetic
The share is the hormone's molecular weight divided by the ester's, both from PubChem. For testosterone enanthate: 288.4 ÷ 400.6 = 0.72, so 100 mg holds about 72 mg of testosterone.
| Ester | Ester g/mol | Hormone g/mol | Hormone in 100 mg | PubChem |
|---|---|---|---|---|
| Test P | 344.5 | 288.4 (testosterone) | 83.7 mg | CID 5995 |
| Test E | 400.6 | 288.4 (testosterone) | 72 mg | CID 9416 |
| Test C | 412.6 | 288.4 (testosterone) | 69.9 mg | CID 441404 |
| Test U | 456.7 | 288.4 (testosterone) | 63.1 mg | CID 65157 |
| Deca | 428.6 | 274.4 (nandrolone) | 64 mg | CID 9677 |
The lightest ester here, Test P, is 83.7 mg of hormone per 100 mg. The heaviest, Test U, is 63.1 mg. Deca is 64 mg of nandrolone, a different hormone with a lighter molecule (274.4 g/mol).
Why it matters when comparing esters
200 mg of Test E and 200 mg of Test C look like the same amount. They are about 144 mg and 140 mg of testosterone. The difference is small for these two, but between Test P and Test U the same number on the label is 41.1 mg apart in hormone.
Ester weight is separate from how long an ester lasts. The chart shows one 100 mg dose of three testosterone esters. The heights differ partly because of ester weight and partly because a slow release spreads the same amount over more days.
- 100 mg Test P
- 100 mg Test E
- 100 mg Test U
Blends
Sustanon mixes four testosterone esters. Pedplot splits 250 mg into its parts and applies each ester's own share:
| Part | mg in the blend | Testosterone |
|---|---|---|
| Testosterone propionate | 30 mg | 25.2 mg |
| Testosterone phenylpropionate | 60 mg | 41.4 mg |
| Testosterone isocaproate | 60 mg | 45 mg |
| Testosterone decanoate | 100 mg | 65 mg |
In total, 250 mg of the blend is about 177 mg of testosterone.
How the plotter uses it
Every dose entered in the plotter is the amount of the ester. The plotter multiplies it by the share before drawing, so the curve is in milligrams of the hormone. Orals, GLP-1s and peptides are not esters, so their share is 100%. The share appears as a chip under the compound field and in each compound page's key numbers. See the methodology for the full catalog.
Sources
- Computed (PubChem). PubChem, testosterone propionate (CID 5995): molecular weight 344.5 g/mol
- Computed (PubChem). PubChem, testosterone enanthate (CID 9416): molecular weight 400.6 g/mol
- Computed (PubChem). PubChem, testosterone cypionate (CID 441404): molecular weight 412.6 g/mol
- Computed (PubChem). PubChem, testosterone undecanoate (CID 65157): molecular weight 456.7 g/mol
- Computed (PubChem). PubChem, nandrolone decanoate (CID 9677): molecular weight 428.6 g/mol
- Computed (PubChem). PubChem, testosterone (CID 6013): molecular weight 288.4 g/mol
- Computed (PubChem). PubChem, nandrolone (CID 9904): molecular weight 274.4 g/mol
The model and its limits are on the methodology page.