Enter a dose, ester and injection frequency and this tool models the blood level it produces at steady state, including the peak, the trough, and how far your levels swing between injections. Absolute levels are anchored to published human dose-response data rather than estimated, and the model exists to help you plan when to test, not to replace testing.
At 2×/week your level swings ±13% around the average each cycle.
Splitting the same weekly dose to EOD would tighten that to ±5% with no change to the average. Flatter levels mean steadier mood, libido and side-effects.
Educational estimate, not medical advice and not a prescription. Real levels vary widely with SHBG, body composition, aromatisation, clearance and product purity, so treat every number as a wide range. A single blood draw at trough beats this model. Use it to decide when to test and how to space injections, then confirm with actual bloodwork.
Injected testosterone esters show what pharmacologists call flip flop kinetics. Release from the oil depot is slower than clearance from the blood, so the ester's release rate, not the body's clearance rate, determines the shape of the curve. Each ester carries a different half life and a different percentage of testosterone by weight, which is why 100 mg of propionate and 100 mg of undecanoate behave nothing alike.
The absolute scale is calibrated to a landmark dose response study in which men received graded weekly doses of testosterone enanthate under suppression, producing a clean and proportional relationship between milligrams injected and blood level achieved.
The same weekly dose, split more often, produces the same average level with a far smaller swing. Weekly enanthate swings roughly plus or minus a third around the average. Split across two injections a week, that drops to around plus or minus a thirteenth, with no change in the total dose.
That flatness is what people feel. Large peaks and crashing troughs drive mood swings, fluctuating libido and inconsistent side effects. The frequency optimiser shows you the trade directly. If you want to work the problem backwards — picking the level you want and solving for the dose — use the TRT Dose Calculator instead.
Individual variation is enormous. Clearance, distribution volume, SHBG, aromatisation and product purity all vary between people, which is why every number here carries a wide band. The model is deliberately capped at moderate confidence, because a model is not a blood test.
Its real value is planning. It tells you when your trough falls, so you know when to draw blood for a result that actually means something. Once you have that result, run it through the Bloodwork Analyzer to see it in context, or check Estradiol & Aromatase Inhibitor guidance if it comes back with symptoms.
Testosterone enanthate has a half life of roughly four and a half days and cypionate roughly eight days, which is why both are commonly injected once or twice weekly. Propionate is around two days and needs far more frequent injection to stay stable.
At trough, meaning immediately before your next injection. That is the lowest point in the cycle and the standard reference point for adjusting a protocol. Testing at a random point produces a number that cannot be compared to anything.
Roughly four to five half lives of the ester. For enanthate that is about three weeks, for cypionate closer to five to six. Testing before then measures a level that is still climbing.
No, it does not change your average level, because the total weekly dose is the same. What it changes is stability, reducing the gap between peak and trough substantially, which is what most people notice in mood, libido and side effects.
Because individual pharmacokinetics vary widely, and because injection timing, product concentration and assay differences all shift the number. Trust the blood test. Use the model to decide when to draw it and how to adjust frequency.
