Half-life & timing · Visualizer
Half-Life & Re-Dose Timing Visualizer
A half-life is the time it takes to clear half a dose from your system, and it quietly sets the rhythm of a whole dosing schedule: fast in and fast out, or slow and steady. Give this visualizer three things — a compound's half-life, how often it's dosed, and how many doses — and it draws the curve people actually want to see: how repeated doses pile up into a steady plateau, and where the peaks and troughs settle once they do. It's a teaching picture in relative units, not a real blood level, and it's honest about what a simple model can and can't tell you.
Half-life and re-dose timing visualizer
- Levels build to about 2.00× a single dose at this interval (accumulation ratio).
- Reaches a practical plateau after ~5d (about 5 half-lives).
- At steady state, peaks land near 2.00× and troughs near 1.00× a single dose.
What this simplified model ignores
This is a one-compartment, first-order model in relative units — a teaching picture of timing and accumulation, not a predicted blood level. It assumes the whole dose appears instantly (IV-like), so real subcutaneous peaks are lower and rounder than these. It ignores bioavailability, distribution, protein binding, active metabolites, and any saturable (nonlinear) kinetics. And the half-life you enter is only as good as its source — many research peptides have no published human PK at all.
What a half-life actually tells you
Half-life is the clock behind everything else on this chart. It's the time it takes for half a dose to clear — after one half-life, half is left; after two, a quarter; after four or five, it's basically gone, the way a cup of coffee wears off in steps rather than all at once. That one number sets the shape of the curve: a short half-life means each dose mostly clears before the next one lands, so levels swing up and down; a long half-life means doses overlap and stack into a smooth plateau. Under the hood it's one line of math, k = ln(2) ÷ half-life, and the rest of the curve follows from it.
Why levels climb to a plateau, then stop
Dose something faster than your body clears it, and the leftovers from earlier doses ride along with each new one. That's accumulation, and it's why a compound can feel stronger a few weeks in than it did on day one. But it doesn't climb forever: as the level rises, so does the amount cleared every interval, until what goes in each time matches what leaves. That truce is steady state, and you reach it after roughly five half-lives regardless of the dose size. The accumulation ratio works out to1 ÷ (1 − e^(−k·interval)) — and when the dosing interval equals the half-life, that lands at exactly 2×, which is what the "t½ = interval" example shows on the chart.
Why a long half-life means smoother, more forgiving dosing
A long half-life is a forgiving one. A once-weekly compound with a roughly week-long half-life barely dips between doses — the curve rides almost flat, and taking it a day late hardly moves the line. Something with a half-life measured in minutes to hours is the opposite animal: it spikes and clears in a hurry, which is why those get dosed several times a day. Flip between the weekly and the short-acting examples above and you'll watch the same model draw those two very different pictures.
What this model deliberately leaves out
Being honest about what it can't see is half the point of a tool like this, so here's the fine print. It assumes the whole dose shows up the instant you take it — true for an IV push straight into a vein, but not for a shot into the fat under the skin (a subcutaneous injection), where the compound trickles in over time and the real peaks come lower and rounder. It also ignores how much of a dose actually reaches your blood (bioavailability), how the compound spreads into tissues, protein binding, active breakdown products, and any kinetics that jam up at higher doses. One more limit worth saying out loud: a half-life is not the same as how long something "works" — the effect can outlast or lag the blood level. And the curve is only ever as good as the half-life you feed it. Plenty of research peptides have no published human pharmacokinetics at all, so treat those numbers as educated estimates, not facts.
How this pairs with the other tools
Half-life answers how often. Ourreconstitution & dosing calculatorhandles how much to draw into the syringe for each of those doses, and thecost-per-dose calculator turns the whole schedule into a dollar figure you can compare between vendors. Together they cover the three questions people ask before starting anything: how much, how often, and what it costs.
Model and guidance current as of July 2026. Educational information, not medical advice.