Testosterone dose calculator
A weekly dose split by injection frequency — milligrams, millilitres and syringe units per shot — with the modelled peak-to-trough swing for cypionate, enanthate and propionate at that cadence. Free, no account.
Two calculations, and they are usually run together. The first is arithmetic: a weekly dose divided by the number of injections gives milligrams per shot, that divided by the vial's concentration gives millilitres, and that times a hundred gives units on a U-100 syringe. 120 mg a week at 200 mg/ml, twice weekly, is 60 mg per shot, 0.3 ml, 30 units.
The second is why the cadence question exists at all. Testosterone esters differ in how fast they release, and that decides how much a level rises and falls between injections. This page models it from the half-life and time-to-peak the app uses, and reports the peak-to-trough ratio — how many times higher the peak is than the trough at steady state. Once-weekly cypionate is a noticeably bigger swing than twice weekly; propionate, with a half-life under a day, is a bigger swing again at any weekly cadence, which is the entire reason it is injected as often as it is.
Established clinical use Testosterone therapy itself is established clinical use and requires a prescription. Off-label or community practice The specific cadences below — twice weekly, every other day — are common clinical and community practice rather than what most approved labelling specifies, which is longer intervals. This page computes what a cadence does to a modelled level; it does not tell anyone which dose or cadence is right for them, and that is a decision for the clinician who prescribes it.
How the math works
volume (ml) = per injection (mg) ÷ vial concentration (mg/ml)
units (U-100) = volume (ml) × 100
interval (hours) = 168 ÷ injections per week
accumulation = 1 ÷ (1 − 2^(−interval ÷ half-life))
time to steady state ≈ 5 × half-life
The peak-to-trough figure is not a formula but a simulation: the app's own
pkCurve function builds a one-compartment absorption-and-elimination curve
matched to the compound's published time-to-peak, and the page adds up enough repeated
doses for the total to stop changing, then reads the highest and lowest points of the last
interval. That is what "steady state" means — not that the level is flat, but that each
cycle repeats the one before.
The same dose at five cadences
Worked for 120 mg a week of testosterone cypionate at 200 mg/ml, so only the split changes. The ratio column is the modelled peak divided by the modelled trough — closer to 1 is flatter.
| Cadence | Per injection | Volume | Units (U-100) | Peak:trough |
|---|---|---|---|---|
| Once weekly | 120 mg | 0.600 ml | 60 u | 1.72× |
| Twice weekly | 60 mg | 0.300 ml | 30 u | 1.21× |
| Three times weekly | 40 mg | 0.200 ml | 20 u | 1.1× |
| Every other day | 34.3 mg | 0.171 ml | 17.1 u | 1.07× |
| Daily | 17.1 mg | 0.086 ml | 8.6 u | 1.02× |
Where these half-lives come from, and what they are not
Provenance matters more here than the incumbents on this query admit. The figures are the ones app.html's PK table carries — cypionate 6 days, enanthate 4.5 days, propionate 19 h, with times to peak of 2 days, 36 h and 12 h — drawn from published pharmacokinetic literature on intramuscular ester preparations. None of the three is flagged as an estimate; where a compound's half-life in this app is an estimate, every page saying so is a rule rather than a courtesy.
What they are not: a prediction of your serum testosterone. A one-compartment model with a matched Tmax reproduces the shape of a release curve well and says nothing about absolute concentration, which depends on the injection site and depth, the volume, your SHBG, and your clearance. The number that settles what a protocol is actually doing is a trough draw taken immediately before the next injection, on a total testosterone assay whose method you know.
Questions people actually ask
Cypionate or enanthate — does it matter?
Pharmacokinetically, barely. The modelled half-lives here differ by about a day and a half (6 days against 4.5 days), which at a weekly or twice-weekly cadence moves the peak-to-trough ratio only slightly. The app's own entry for enanthate says it is clinically interchangeable with cypionate in all protocols. Where they differ in practice is the carrier oil and local tolerability, not the curve.
Why does splitting the dose change anything if the weekly total is the same?
Because the total is not what varies — the swing is. Injecting once a week means the level peaks a day or two after the shot and falls for the rest of the week; twice weekly halves both the rise and the fall. Whether a flatter curve feels better is individual, and the honest position is that the model tells you the swing, not whether you will notice it.
How long before a change shows up in bloodwork?
About five half-lives to reach the new steady state — roughly 30 days for cypionate, 23 for enanthate, and 4 for propionate. Drawing labs before that measures a level still on its way somewhere, which is the most common reason two panels a fortnight apart disagree.
Does this calculator suggest a dose?
No, and it will not. It takes a dose you enter and tells you what that dose looks like split different ways. Which dose is appropriate depends on symptoms, bloodwork, haematocrit, prostate history and a clinical examination, and belongs with the person who prescribes it.
Related: testosterone cypionate half-life and enanthate half-life, the free testosterone calculator, and the insulin syringe unit converter.
The app charts this curve against the doses you have actually logged, and flags a bloodwork result against the reference range your own lab printed.
Save this dose to your logThis calculator does the arithmetic you typed and nothing else. It does not know what is actually in your vial, whether the label is accurate, or anything about you. Confirm the vial strength and the diluent volume on your own label before you draw, and take dosing decisions to a qualified provider.