Last updated: October 2026
Masteron Dosage Calculator
Quick answer: A 300 mg/week dose over 3.5 shots from a 100 mg/mL vial is 0.857 mL (85.7 units) per shot, ≈ 252 mg active hormone/week. mL = (weekly mg ÷ shots) ÷ mg/mL.
Injectable ester — about 84% of each mg is Masteron; the calculator converts dose → mL, units and active mg. Aromatizes: No. Liver-strain (17α-alkylated): No. Half-life: Propionate ≈ 2 days (drug monograph); Enanthate.
About this calculator
Masteron (drostanolone) is a DHT-derived injectable that does not aromatize. It comes as a fast propionate (≈84% active) and a slow enanthate (≈73% active). This calculator converts a dose into mL and U-100 units; pick the ester to set the active fraction. The propionate has a monograph half-life; the enanthate’s is not established, so its timeline is omitted.
Drostanolone is a 2α-methyl dihydrotestosterone derivative valued for its non-aromatizing, "dry" profile. Propionate is usually 100 mg/mL and enanthate 200 mg/mL.
How the injection-volume maths works
Propionate is about 84% drostanolone (304.5 ÷ 360.5) and enanthate about 73% (304.5 ÷ 416.6), so the same labelled dose delivers different active milligrams. The calculator applies the factor for whichever ester you choose.
How to use this calculator
Pick the ester first, since propionate and enanthate carry different shares of active hormone. Next type in the total for the week, the concentration on your vial, and how many injections that total is spread across. The calculator returns the volume for each injection, the equivalent U-100 syringe units, and the drostanolone that the shot actually delivers.
Worked examples
Weekly dose: 300 mg · Concentration: 100 mg/mL · Injections/week: 3.5
85.71 mg/shot ÷ 100 = 0.857 mL (85.7 units) · active ≈ 252 mg/week
Weekly dose: 400 mg · Concentration: 200 mg/mL · Injections/week: 2
200 mg/shot ÷ 200 = 1 mL (100 units) · active ≈ 336 mg/week
Half-life & clearance
Illustrative single-dose elimination by half-life (t½ ≈ 2 days). Each marker is one half-life; after ~5 the dose is essentially cleared. For an oil depot the real rise-and-fall is slower (absorption-limited release), so treat this as a timing reference, not a blood-level prediction.
Masteron propionate has a ~2-day depot (a drug-monograph figure, not a primary trial); the enanthate has no citable human half-life, so we show the conversion without a timeline for that ester.
How to interpret your result
The volume is what you draw to on the syringe, and the units figure is the same volume counted on a 100-unit scale. Use the active-milligram line when you swap between propionate and enanthate or between vial strengths, because it shows the real hormone regardless of the label. The timing reference is a plain decay curve built from a documented half-life, so it is shown for the propionate only.
Aromatization, liver & monitoring
As a DHT derivative drostanolone does not aromatize, so it adds no estrogen of its own. It is not 17α-alkylated, so it is not directly hepatotoxic; its androgenic nature (hair, prostate) is the more typical concern.
Common mistakes
Mixing the two esters is the usual error — a 100 mg/mL propionate and a 200 mg/mL enanthate need different draw volumes for the same labelled dose. Set the ester first, then read the mL.
Masteron at a glance
| Property | Masteron |
|---|---|
| Form | Injectable (oil/suspension) |
| Active fraction | 0.84 (esterFactor) |
| Half-life | Propionate ≈ 2 days (drug monograph); Enanthate — not reliably established |
| Aromatizes | No — a DHT derivative, not an aromatase substrate. |
| Liver (17α-alkylated) | No (not 17α-alkylated). |
| Approx. detection | ~3 weeks (propionate); longer for the enanthate. |
Masteron propionate and enanthate draw table
These rows show what the Masteron calculator produces for each ester at one label strength, with the week split into two shots. They are arithmetic illustrations only and carry no advice about what anyone should inject. Each active figure is the shot milligrams times the ester factor, which is why propionate and enanthate diverge even when the label dose matches.
| Ester | Vial | Weekly dose | Shots/week | mL per shot | Units | Active per shot |
|---|---|---|---|---|---|---|
| Propionate | 100 mg/mL | 300 mg | 2 | 1.5 mL | 150 | 126 mg |
| Propionate | 100 mg/mL | 400 mg | 2 | 2 mL | 200 | 168 mg |
| Enanthate | 200 mg/mL | 300 mg | 2 | 0.75 mL | 75 | 109.5 mg |
| Enanthate | 200 mg/mL | 400 mg | 2 | 1 mL | 100 | 146 mg |
How Masteron differs from Primobolan
Masteron and Primobolan are the two DHT-derived injectables on this site. Neither aromatizes and neither is 17α-alkylated, so on those two rows the pages read almost the same. What separates them is the timing evidence and the ester arithmetic. Masteron propionate has a monograph half-life of about 2 days, while Masteron enanthate has no reliably established figure. Primobolan is described by a pharmacology textbook (Westreich 2011) at about 10.5 days. So the Masteron page can draw a decay curve only for the propionate, and the Primobolan page carries a single half-life. On active fraction, Masteron propionate is 0.84 and enanthate 0.73, against 0.73 for Primobolan, which means Masteron enanthate and Primobolan deliver the same share of active hormone per label milligram while the propionate delivers more. Because the formula is shared, the choice between the pages is about which ester and which evidence you are reading, not a different method.
Frequently asked questions
Related guides
Other compounds
Other calculators
References
- PubChem — drostanolone (molecular weight), CID 6011
- PubChem — drostanolone propionate (molecular weight), CID 224004
- PubChem — drostanolone enanthate (molecular weight), CID 13014314
- Kicman AT. Pharmacology of anabolic steroids. Br J Pharmacol 2008;154(3):502–521
Every citation URL was verified to return HTTP 200. Citations are provided for transparency and education and do not imply the cited authors or bodies endorse this tool. Anabolic steroid use carries real health risks — always consult a qualified clinician.
How this is calculated
Weekly milligrams are divided by the number of shots, and the result is divided by the vial strength to give mL, which is multiplied by 100 for units. The active portion uses the ester factor: 0.84 for propionate (304.5 ÷ 360.5) and 0.73 for enanthate (304.5 ÷ 416.6), each built from PubChem molecular weights. The propionate decay figure follows ke = ln2 ÷ t½ with the usual five half-life cutoff. It is arithmetic only — nothing you enter is stored or sent anywhere, and the result is not medical advice or an endorsement of anabolic steroid use.