Last updated: June 2026
NPP Dosage Calculator
Quick answer: A 100 mg/week dose over 3.5 shots from a 100 mg/mL vial is 0.286 mL (28.6 units) per shot, ≈ 67 mg active hormone/week. mL = (weekly mg ÷ shots) ÷ mg/mL.
Injectable ester — about 67% of each mg is NPP; the calculator converts dose → mL, units and active mg. Aromatizes: Partial / weak. Liver-strain (17α-alkylated): No. Half-life: ≈ 2.7 days (65 h) oil-depot; free nandrolone clears in < 4.3 h.
About this calculator
NPP is the short-ester form of nandrolone (19-nortestosterone). About 67% of each milligram is active nandrolone. This calculator converts your weekly dose into draw volume and syringe units, and shows the depot half-life that drives its more-frequent injection schedule versus long-ester Deca.
NPP is nandrolone attached to the short phenylpropionate ester — the fast counterpart to long-ester Deca-Durabolin. It is usually supplied at 100 mg/mL, and about 67% of each milligram is the parent hormone.
How the injection-volume maths works
The phenylpropionate ester accounts for a third of the molecule’s weight (274.4 ÷ 406.6 = 0.67), so a 100 mg dose delivers about 67 mg of nandrolone. The calculator shows that active figure alongside the draw volume.
How to use this calculator
Enter your weekly dose, the concentration printed on your vial (mg/mL), and how many injections per week. The result updates instantly with the mL to draw, the U-100 syringe units, and the active-hormone milligrams delivered.
Worked examples
Weekly dose: 100 mg · Concentration: 100 mg/mL · Injections/week: 3.5
28.57 mg/shot ÷ 100 = 0.286 mL (28.6 units) · active ≈ 67 mg/week
Weekly dose: 150 mg · Concentration: 100 mg/mL · Injections/week: 3
50 mg/shot ÷ 100 = 0.5 mL (50 units) · active ≈ 101 mg/week
NPP dose chart
Common doses at 100 mg/mL, 2 injections/week (each row is the calculator’s arithmetic worked out):
| Weekly dose | mL/shot | Units | Active/week |
|---|---|---|---|
| 50 mg | 0.25 mL | 25 | 34 mg |
| 75 mg | 0.375 mL | 37.5 | 50 mg |
| 100 mg | 0.5 mL | 50 | 67 mg |
| 150 mg | 0.75 mL | 75 | 101 mg |
| 200 mg | 1 mL | 100 | 134 mg |
Half-life & clearance
Illustrative single-dose elimination by half-life (t½ ≈ 3 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.
With a ~2–3 day depot, NPP is injected more often than Deca to keep levels steady; once the ester is cleaved, free nandrolone itself clears within hours (Minto 1997). The 19-norandrosterone metabolite, however, remains detectable for months.
How to interpret your result
The result is the volume to draw per injection and its mark on a U-100 syringe. The active-hormone figure shows how much actual NPP that ester delivers — useful when comparing esters or switching concentrations. The half-life figure is a pharmacokinetic timing reference only.
Aromatization, liver & monitoring
Nandrolone aromatizes only weakly but is strongly progestogenic, which drives its own estrogen-like and prolactin-related effects. It is not 17α-alkylated, so it is not directly hepatotoxic.
Common mistakes
Treating NPP and Deca as interchangeable is the common error — they share the parent hormone but their esters give very different injection frequencies and active fractions (0.67 vs 0.64).
NPP at a glance
| Property | NPP |
|---|---|
| Form | Injectable (oil/suspension) |
| Active fraction | 0.67 (esterFactor) |
| Half-life | ≈ 2.7 days (65 h) oil-depot; free nandrolone clears in < 4.3 h |
| Aromatizes | Partial / weak — aromatizes far less than testosterone; mainly progestogenic. |
| Liver (17α-alkylated) | No (not 17α-alkylated). |
| Approx. detection | Very long — the 19-norandrosterone marker is detectable for months. |
Frequently asked questions
Related guides
Other compounds
Other calculators
References
- Minto CF et al. Pharmacokinetics and pharmacodynamics of nandrolone esters in oil vehicle. J Pharmacol Exp Ther 1997;281(1):93–102 (PMID 9316843)
- PubChem — nandrolone (molecular weight), CID 9904
- PubChem — nandrolone phenylpropionate (molecular weight), CID 229455
- 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
For injectables the calculator divides your weekly dose by the number of injections, then by the vial concentration, to get the mL per shot — and multiplies by 100 for U-100 syringe units (1 mL = 100 units). The active-hormone milligrams are the dose multiplied by the esterFactor (the parent hormone’s molecular weight divided by the full ester’s molecular weight, both from PubChem). For orals it divides the daily dose by your doses-per-day and tablet strength to get tablets per dose. Half-life timing uses ke = ln2 ÷ t½ and the ~5-half-life rule of thumb for steady state and clearance. 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.