What Is Masteron? Half-Life, Dosing Math & How to Track It
Also known as: Drostanolone Propionate · Mast P · Drolban
Masteron is the common name for drostanolone propionate, a DHT-derived anabolic steroid attached to a short propionate ester — which is why it is typically injected every other day. The ester’s half-life is only ~2–3 days, and about 84% of the milligrams in the vial are drostanolone itself. As a DHT derivative it does not aromatize to estrogen, but it carries its own lipid, skin, and prostate-related monitoring considerations. Educational only; not a recommendation to use.
What Masteron is and how it works
Masteron is the trade name most people use for drostanolone propionate — a steroid derived not from testosterone directly but from dihydrotestosterone (DHT). That lineage matters: like DHT itself, drostanolone cannot be converted to estrogen by aromatase, so it does not raise estradiol the way testosterone or boldenone can.
Drostanolone was originally developed as a medical antiestrogen — marketed for a time as Drolban for breast cancer treatment — before that use was discontinued in favor of newer drug classes. Its androgenic activity is high relative to its anabolic activity, which is the receptor-level reason its side-effect list leans toward androgenic ones like skin and hair changes rather than estrogenic ones.
About 84% of the milligrams in drostanolone propionate are drostanolone itself, with the propionate ester making up the rest — a short ester that is cleaved off quickly, which is why the injection schedule has to be frequent.
Dosing math & the mg/mL trap
Masteron is labeled by concentration like any injectable ester: volume (mL) = dose (mg) ÷ concentration (mg/mL). Because propionate esters are known for causing more injection-site discomfort than longer esters, getting the volume right — and not over-drawing — matters for comfort as much as accuracy.
On an every-other-day schedule the weekly total is typically split across three or four shots; divide by the injection count first, then apply the volume formula for each individual draw.
| Amount | 100 mg/mL | 150 mg/mL | 200 mg/mL |
|---|---|---|---|
| 50 mg | 0.50 mL (50u) | 0.33 mL (33u) | 0.25 mL (25u) |
| 100 mg | 1.00 mL (100u) | 0.67 mL (67u) | 0.50 mL (50u) |
| 150 mg | 1.50 mL (150u) | 1.00 mL (100u) | 0.75 mL (75u) |
Volume to draw at three reference concentrations (U-100 syringe units in parentheses). Reference numbers for the arithmetic only — the HRT tab of the calculator handles any concentration.
Half-life & what it means for frequency
A ~2–3-day ester half-life means Masteron is almost always run every other day; a weekly injection would spend most of the week well below any useful level. The short ester does mean it reaches a steady blood level quickly compared to a long-ester compound.
It also clears quickly after stopping — typically within a couple of weeks — which is useful if a side effect appears and the plan is to stop rather than push through it.
What to monitor & the real risks
Because it doesn’t aromatize, Masteron’s risk profile leans androgenic rather than estrogenic: hair loss (in those genetically predisposed to androgenic alopecia) and acne are the most commonly reported skin/hair effects, driven by its high androgenic activity. As a DHT derivative, prostate health is worth a baseline and ongoing conversation, particularly with a family history of prostate issues.
A lipid panel matters here too — DHT derivatives are generally associated with meaningful HDL suppression — alongside standard hematocrit monitoring for any AAS. Like other AAS, it suppresses the HPTA, so total/free testosterone and LH/FSH are worth tracking if fertility or post-use recovery is a concern.
How to track Masteron in Frontload
Log every Masteron injection with its dose and site — at every-other-day frequency it is easy to lose the pattern without a log. Keep lipids, hematocrit, and any skin/hair notes trending alongside it so early androgenic changes are visible rather than a surprise months in.
Model it yourself · free, no account
Dosing Calculator (HRT tab)
Model it yourself: enter your dose and vial concentration on the HRT tab and get the exact mL and syringe units for any amount — the same math built into the Frontload app.
Related compounds
Related reading: TRT Math: what mg/mL actually means · Injection frequency: daily vs EOD vs weekly
Frequently asked questions
What is Masteron’s generic name?
Drostanolone propionate — Masteron is the trade name most commonly used. It is derived from DHT rather than testosterone, which is why it does not aromatize to estrogen.
What is the half-life of Masteron?
Roughly 2–3 days for the propionate ester, which is why it is almost always injected every other day. It also clears relatively quickly — typically within a couple of weeks — after the last shot.
How do you calculate a Masteron dose in mL?
Volume (mL) = dose (mg) ÷ concentration (mg/mL). A 100 mg amount from a 100 mg/mL vial is 1.00 mL, or 100 units on a U-100 syringe. The HRT tab of the calculator handles any concentration.
What should I monitor on Masteron?
A lipid panel (DHT derivatives are notable HDL suppressors), hematocrit, and — given its high androgenic activity — hair and skin changes and prostate health. Total/free testosterone and LH/FSH are worth a baseline too, since it suppresses the HPTA like other AAS.
This is educational information, not medical advice. Doses and protocols above reflect published references and community practice — protocol decisions belong with your prescribing physician. Generic names used throughout. How this reference is built & how the AI is tested →
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