Testosterone Esters
Seven esters, one hormone. What changes is the release curve and the weight.
An ester is a fatty-acid chain attached to the testosterone molecule. It does not change what is ultimately delivered. It changes two things: how quickly the compound is released from the injection site, and what proportion of the labelled weight is testosterone rather than chain.
| Ester | Chain | Half-life | Testosterone per 100 mg |
|---|---|---|---|
| Propionate | 3-carbon (propanoic acid) | Approximately 0.8 days, often quoted as around 20 hours | 83 mg |
| Phenylpropionate | Phenyl-substituted 3-carbon | Approximately 1.5 days | 77 mg |
| Isocaproate | 6-carbon, branched | Approximately 2 days | 72 mg |
| Enanthate | 7-carbon (heptanoic acid) | Approximately 4.5 days | 70 mg |
| Cypionate | 8-carbon (cyclopentylpropionic acid) | Approximately 5 days | 69 mg |
| Decanoate | 10-carbon (decanoic acid) | Approximately 7.5 days | 64 mg |
| Undecanoate | 11-carbon (undecanoic acid) | Approximately 20 to 34 days depending on the carrier oil | 61 mg |
Reading the table
Chain length and half-life move together. So does the testosterone fraction, in the opposite direction: the longer the chain, the more of each milligram is ester. Propionate is the shortest and the most testosterone-dense at roughly 83%. Undecanoate is the longest and the least, at roughly 61%.
Half-lives are approximate published figures. They vary between sources, and for undecanoate they vary with the carrier oil as much as with the chain.