OptiPin
Testosterone microdosing calculator
Take the weekly dose your prescriber set and split it across daily, every-other-day or every-third-day injections. You get the units to draw per shot and the one number the other calculators leave out: how flat the curve actually becomes.
How to use this microdosing calculator
What microdosing changes and what it does not
It does not raise your weekly exposure. Seven 20 mg injections deliver the same 140 mg as one 140 mg injection. Average level across the week is essentially unchanged. Anyone promising more from the same milligrams is describing a different dose, not a different schedule.
It flattens the curve and most of the flattening is cheap. On cypionate the model puts once weekly near 2.3 to 1 and twice weekly near 1.3 to 1. That single step removes most of the swing. Every other day gets to about 1.11 to 1 and daily to about 1.03 to 1, so the last two steps cost four more injections a week for a small remaining gain.
The shorter the ester, the more frequency matters. Propionate on a weekly schedule is not a protocol, it is a spike. The same schedule that barely changes undecanoate is the difference between usable and unusable on propionate. That is the whole reason the ester selector is here.
A trough-timed lab result can rise without the dose changing. If you move from weekly to daily and your trough testosterone reads higher, that is the trough coming up to meet the average, not more testosterone. It is worth knowing before anyone reads the result as a dose increase.
It restarts the clock. Changing frequency needs four to five half-lives before the curve settles into its new shape, so roughly four to six weeks on cypionate or enanthate. The TRT timeline covers what that means for bloodwork.
Peak-to-trough by schedule
| Ester | Weekly | 2×/week | EOD | Daily |
|---|---|---|---|---|
| Testosterone propionate (t½ ~1.0 d) | 25.9 : 1 | 3.01 : 1 | 1.49 : 1 | 1.11 : 1 |
| Testosterone cypionate (t½ ~3.8 d) | 2.29 : 1 | 1.33 : 1 | 1.11 : 1 | 1.03 : 1 |
| Testosterone enanthate (t½ ~4.5 d) | 2.27 : 1 | 1.38 : 1 | 1.14 : 1 | 1.04 : 1 |
Steady-state peak divided by steady-state trough, at a constant weekly total. Computed with the same one-compartment absorption model and the same published half-life and t-max values that drive the half-life calculator, so the two pages agree. It is a model of an idealized depot, not a measurement of you: absorption from a real injection site varies, which tends to blunt the extremes rather than sharpen them. Treat the ratios as a comparison between schedules, not as a prediction of your own numbers.
The floor on measurable volume
This is where microdosing stops being free. Splitting a week into seven makes each volume one seventh the size and syringes do not get more precise as the volume shrinks. At 100 mg a week and 250 mg/mL, a daily injection is 5.7 units on a U-100 syringe. Half a unit of misdraw there is a 9% dosing error, every day. The same protocol at 100 mg/mL is 14.3 units, where the same misdraw is under 4%.
Two things follow. Low weekly totals and high concentrations are the worst combination for daily dosing. Concentration is the lever that fixes it – but it is a prescription change rather than a syringe change, so it is a conversation rather than a decision. And below roughly 10 units, the arithmetic argument for going from every other day to daily is weaker than the measurement argument against it.
The split dose calculator handles the general case, including uneven gaps such as a Monday and Thursday split, where the two doses are deliberately not equal. This page is the microdosing-specific view: even intervals, the peak-to-trough figure, the volume floor.
Frequently asked questions
What is testosterone microdosing?
Taking the same weekly total as many small injections rather than one large one, typically daily or every other day. The weekly dose does not change. What changes is the shape of the curve: smaller, more frequent injections narrow the gap between the peak after a shot and the trough before the next. It is a scheduling change rather than a dose change and the weekly total still belongs to your prescriber.
Does microdosing testosterone raise your levels?
No. Splitting 140 mg a week into seven 20 mg injections delivers the same 140 mg and average exposure over the week is essentially unchanged. What moves is the peak-to-trough ratio: on cypionate, once weekly swings about 2.3 to 1 at steady state, twice weekly about 1.3 to 1, daily about 1.03 to 1. A trough-timed blood test can read higher on a daily schedule simply because the trough is higher.
How many units is a daily testosterone microdose?
Divide the weekly milligrams by 7, divide by your vial concentration, then multiply by 100 for U-100 units. At 140 mg a week and 200 mg/mL, a daily dose is 20 mg = 0.1 mL = 10 units. At 100 mg a week and 250 mg/mL it is 14.3 mg = 0.057 mL = about 5.7 units, where half a unit of misdraw is a 9% error.
Is daily better than every other day?
Flatter, yes. Better is a clinical judgment rather than an arithmetic one. On cypionate the model puts every other day near 1.11 to 1 and daily near 1.03 to 1, so most of the flattening is already done by every other day and the remaining step is small. Against it: seven injections a week and seven very small volumes to measure. Frequency is a conversation with your prescriber.
Does microdosing need subcutaneous injection?
Not necessarily, though small volumes are one reason subcutaneous injection is common on frequent schedules. The point this page makes is arithmetic rather than route: a microdosing schedule produces small volumes and small volumes are harder to measure on any syringe. Route, needle and site belong with your prescriber. The injection guide covers technique.
How long before a schedule change shows in bloodwork?
About four to five half-lives, so roughly four to six weeks on cypionate or enanthate. Changing frequency restarts that clock even at an unchanged weekly dose, because the curve has to settle into its new shape. Draw at the same point in the cycle each time or the result is not comparable to the last one.
Related calculators & guides
- TRT dose calculator, the weekly total converted to mL and insulin units at any frequency.
- Split dose calculator, uneven intervals and fixed days of the week, where the doses are deliberately not equal.
- Half-life calculator, the full curve for 65 compounds, including time to steady state.
- TRT timeline, how long each effect takes and when bloodwork starts to mean something.
- TRT protocols compared, once weekly through daily microdosing, with the trade-offs.
- Testosterone cypionate half-life, why the label number and the literature disagree.
Sources
- Bhasin S, Brito JP, Cunningham GR, et al. Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab 2018;103(5):1715–1744. Behind the monitoring point above: symptoms, adverse effects, testosterone and hematocrit are reassessed after therapy starts and periodically afterwards, aiming at a mid-normal concentration.
- Half-life and time-to-maximum values are the same dataset used by the OptiPin half-life calculator; per-compound provenance and evidence grades are listed there.