Testosterone Enanthate half-life and steady state
4.5 days modelled half-life, peaking 36 h after a dose. What that means for how long it lasts, how much it builds up, and when bloodwork is worth drawing.
- Also known as
- Test E, TE
- Class
- Androgens / TRT
- Modelled half-life
- 4.5 days
- Time to peak
- 36 h
- Formulation
- Oil-based (intramuscular or subcutaneous)
- Cleared per dosing interval
- 42% gone, 58% still present after 3.5 days
- Time to steady state
- ~22.5 days (about five half-lives)
- Accumulation at that cadence
- 2.4× a single dose
- Peak-to-trough at steady state
- 1.35×
- Regulatory status
- Off-label dosing above TRT levels. TRT itself requires prescription.
- Monitoring panel
- Same panel as Testosterone Cypionate.
- Storage
- Room temperature, 20–25 °C, out of direct light.
- Once opened
- Same once opened. Oil-based vials do not get a fridge.
- What ruins it
- Do not refrigerate. Cold thickens the carrier and can bring the ester out of solution. If you see crystals or cloudiness, warm the vial in your hand or a cup of warm water and look again — if it does not clear, do not use it.
- Handling caveat
- General handling practice for this formulation. Your supplier’s own insert or COA overrides anything here.
Enanthate is cypionate's near-twin, and the honest version of this page says so rather than manufacturing a distinction. The ester is a seven-carbon chain instead of eight, which makes the modelled half-life about a day and a half shorter and moves the time-to-peak forward by half a day. The app's own entry for it states the practical upshot directly: clinically interchangeable with cypionate in all protocols.
Where the difference does show up is at the sparse end of the cadence range. On a once-weekly schedule the shorter half-life means slightly less accumulation and a slightly bigger swing than cypionate on the same schedule — a difference of a few per cent, visible on a chart and generally not in a person. At twice weekly or more often it vanishes into the noise of injection site, absorption and assay variability.
The reason both esters exist at all is historical and regional rather than pharmacological: enanthate is the more commonly prescribed preparation across Europe, cypionate across North America. What can differ in practice is the carrier oil and how a given preparation feels going in, which is a formulation property of a particular product rather than of the ester. If you are switching between them, the thing worth knowing is that you are not changing the shape of your curve in any way you will measure.
One dose
pkCurve function — a
one-compartment absorption-and-elimination model with the absorption rate fitted so the
peak lands at the published time to peak.Dosed twice weekly
Charted at twice weekly because that is one of the schedules in the app's own dosing rows. It is what the numbers below are indexed to, not a recommendation about frequency — that is a prescribing decision.
The arithmetic behind those numbers
fraction left after one interval = 2^(−0.78) = 0.583
accumulation ratio = 1 ÷ (1 − 0.583) = 2.4
time to steady state ≈ 5 × half-life = 22.5 days
peak-to-trough = simulated, 2.603 ÷ 1.9252 = 1.35
The accumulation ratio is a closed form; the peak-to-trough figure is not. The generator adds up enough repeated curves for the total to stop changing, then reads the highest and lowest points of the last interval — which is what steady state means in practice. The vertical axis is relative, not a concentration: the shape and the ratios carry across people, the absolute levels do not.
The dosing rows this cadence came from
Off-label or community practice Reproduced from the app's entry so you can see what the chart above is indexed to. Which row applies to a particular person, if any, is a clinical decision this page does not make.
| Label | Amount | Route and frequency |
|---|---|---|
| TRT | 100-150mg/week | Once or twice weekly |
When to draw bloodwork
The panel the app records for Testosterone Enanthate is: Same panel as Testosterone Cypionate.. The pharmacokinetic point is the timing rather than the list: after any change, a level takes about 22.5 days to settle, so a panel drawn sooner measures something still moving. The swing at this cadence is small (1.35×), so draw timing within the interval matters less here than it does for a short-acting compound. Whether a result means anything is a question for the clinician who ordered it, read against the reference range your own lab printed. The lab-marker pages cover what the individual analytes measure.
Related: the interactive half-life calculator to try other cadences.
The app draws this curve from the doses you actually logged — your dates, your cadence — and projects seven days forward from the last one.
Save this dose to your log