Calculator

Testosterone Enanthate Half-Life Calculator

No curve is modelled on this page, and the reason is the point of it. A half-life for the enanthate ester in humans is not something Prof. Peptide has been able to read from a label or a published study — the label’s own figure is for testosterone rather than the depot, and the nearest measured ester half-life found was in monkeys. The tool refuses rather than drawing a confident-looking curve from a number nobody checked.

Last reviewed: September 21, 2026

No curve is modelled here, because no half-life for it has been read from a source. Three sources were opened on 2026-09-21 and none of them supports a human half-life for the ester. The testosterone enanthate prescribing information gives a half-life for TESTOSTERONE itself — \u201cconsiderable variations ... ranging from 10 to 100 minutes\u201d — which is the hormone, not the oil depot a curve would model. A search for a human pharmacokinetic study returned none; the only enanthate terminal half-life found, about four days, is from a 1990 study in cynomolgus monkeys. And the figure carried in Prof. Peptide\u2019s own iOS app, ~4.5 days, is attributed there to a book chapter that has not been opened and is explicitly marked as not an FDA-label figure.

A curve looks far more certain than the number it was drawn from. Producing one from a figure nobody has checked would make an unsourced number look measured, which is the opposite of what this tool is for.

What was checked, and why none of it qualifies

The FDA prescribing information. Testosterone enanthate’s label states a half-life for testosterone itself — “considerable variations”, ranging from 10 to 100 minutes — which is the hormone once it has been released from the injected depot. That is a different quantity from the depot’s own release half-life, which is what determines how often the ester needs to be injected.
A human pharmacokinetic study of the ester. A search for one returned none. Without a human PK study, there is no measured release half-life for the enanthate depot to cite.
The nearest measured figure found. A terminal half-life of about four days for testosterone enanthate, but from a 1990 study in cynomolgus monkeys — an animal figure, not a human one, and not treated as equivalent here.

A separate figure, approximately 4.5 days, appears in Prof. Peptide’s own iOS app. That figure is attributed there to a book chapter that has not been opened for this page, and the app itself marks it as not an FDA-label figure — so it is reported here as a fact about what the app states, not adopted as a sourced half-life for this tool.

The calculator above will model a curve for testosterone enanthate the moment a human pharmacokinetic source for the ester is read and added to Prof. Peptide’s reference module — not before. Until then, this page states the absence rather than drawing a curve from a number nobody has checked.

FAQ

testosterone enanthate half life calculator

This page cannot model a curve for testosterone enanthate, because Prof. Peptide has not been able to read a human pharmacokinetic source for the ESTER's own half-life — see the sourcing note below for what was checked and why each source fell short.

What is the half-life of testosterone enanthate?

Prof. Peptide has not identified a human pharmacokinetic study or FDA label establishing testosterone enanthate's own elimination half-life as an ester. The enanthate prescribing information states a half-life for testosterone itself (10 to 100 minutes, "considerable variations"), which is the hormone once released — not the oil-based depot that determines how often the ester is injected. Figures commonly quoted online (around 4.5 to 8 days) trace to sources this page could not verify as human pharmacokinetic data — see below.

Why doesn't Prof. Peptide show a half-life for testosterone enanthate?

Because the tool that would model it refuses to draw a curve from a number nobody has read from a source — a curve looks more certain than the figure behind it, and producing one from an unverified number would make it look measured when it isn't. Three sources were checked; none supports a human ester half-life. That refusal is explained in full below rather than papered over with an unsourced figure.

For the arithmetic of a testosterone dose’s volume and syringe reading (which needs only the concentration printed on the vial, not a half-life), see the TRT dose calculator.