A monthly figure is the unit this market advertises in, and it is rarely the unit anyone is billed in. Multiplying it by twelve gives a true year only when four conditions hold at once. The billing period is a calendar month, the price holds as the dose climbs, nothing recurs outside the medication line, and the first charge is the standing one. Those four are seldom all true, which is why the withdrawal trials make the annual total the number worth building.
Why a year, and not three months
The clinical evidence points at continuation, so a purchase made on a monthly page is usually a commitment with no stated end. The behavioral evidence points the other way. A 2026 claims-based analysis reports that in obesity cohorts without diabetes, roughly one third of members are still on therapy at one year. Among people with type 2 diabetes, nearly half discontinue by twelve months and about 70% by twenty-four.[1]
A separate primary-care records study found documented courses of compounded product running longer on average than branded ones, at 10.0 months against 7.8.[2] Both figures matter to the same decision. The year is the horizon the trials imply, and it is also longer than the course most people actually complete, which is exactly the tension a twelve-month prepay tier sits on.
A four-week cycle bills thirteen times
Four weeks is 28 days. A calendar month averages 30.44, because 365.25 divided by twelve is not 28. A year therefore holds just over thirteen four-week cycles, so a page that writes “$199 every 4 weeks” and prints “/mo” beside it is describing a charge that lands thirteen times before the year is out.
That is $2,587 a year, which works out to about $216 a calendar month — roughly 8.7% above the number on the page. Nothing is hidden: the cycle length is usually stated plainly a line away from the price. The conversion is simply one nobody performs while comparing two tabs.
The cleanest proof sits on the same pricing pages. Where a seller also publishes a 52-week tier, 52 weeks is a year by definition, and thirteen charges of $199 is the $2,587 that tier has to total. A twelve-month figure and a four-week figure on one page can be reconciled, and when they are, the four-week rate is the one that was understated.
Twelve weeks is 2.76 months, not three
Eighty-four days divided by 30.44 is 2.76. A twelve-week package sold at $299 therefore costs $108 a month, not the $99.67 that dividing by three produces. The gap is the same 8.7% as the four-week case, and for the same reason: both periods are shorter than the month they are being divided into.
Across a year it compounds quietly. A year holds 4.35 of those packages, so the annual outlay is about $1,300 against the $1,188 that “$99 a month” implies — $112 that never appears on any single invoice. A package quoted at $597 every twelve weeks and advertised as a $199 monthly average is the same shape at a larger size, and lands at $216 a month.
A membership charged on its own clock
Some sellers price the medication and bill membership separately, and the membership runs on a different cadence from the drug. Monthly ones in this market sit between $74 and $149 a month. Annual ones can be a single charge of $199, which spreads to $16.58 a month.
Both are easy to compute once the structure is visible. A plan at $59 a month plus a $199 annual membership is $76 a month and $907 in the first year. A plan at $199 of medication plus a mandatory $149 monthly membership is $348 a month and $4,176 a year, of which the membership alone is $1,788.
A third shape resists arithmetic entirely. Where a figure is labeled as membership plus medication cost, and the medication cost appears nowhere, there is no annual total to build — only a fee and an unknown. That pattern, and the others in how these pages present themselves, is set out in the presentation article.
The opening rate is the one paid once
A first-month rate can sit 50% to 65% below the standing one. Take $60 for a first month against $160 thereafter, a 62.5% opening discount. The year is $60 plus eleven charges of $160, which totals $1,820, or $152 a month. The headline was $60.
Worse for comparison is a page that publishes the opening figure and shows the ongoing rate only at checkout. No annual total can be constructed from it at all. The Federal Trade Commission’s enforcement policy statement on negative-option marketing lists what a buyer is entitled to see before agreeing to a recurring charge. Those disclosures include that charges recur, that they may rise once a trial period ends, the amount or range, and the dates each charge will be submitted.[3]
A dose ladder puts the cheap rung first
Both molecules titrate upward over months, so a price indexed to dose quotes you the rung you occupy briefly and charges you for the rung you occupy for years. The worked arithmetic for that lives in the titration article, and sellers that hold one price across every dose take the variable out of the annual calculation.
What a prepay tier is really pricing
The lowest per-month figure on most pricing pages belongs to the longest term, and that term is usually charged as one payment up front. Against the continuation evidence, committing to a year is a reasonable thing to do. Against the persistence figures above, it is a payment made in full by a population in which roughly a third reach month twelve.
So the discount is not the question. The refund term is. What happens to the unused balance if the drug is stopped for side effects, for a pregnancy, or for a move to a state the service does not cover? That is the term deciding whether the lowest per-month figure was low.
Building the annual number yourself
Four questions do the work, and every one has a written answer. What is the billing period, in days? What is charged when that period repeats, once any opening rate has expired? What else recurs outside the medication line, and on what cadence? And what is the standing rate at the dose expected in month six?
Then one calculation. Count how many billing periods land inside 365 days, multiply by the standing charge, add every recurring fee at its own frequency, and add the opening charge once. That total is the figure that compares against another seller’s total, against a covered copay in the coverage article, and against nothing else.
Where a seller publishes enough to complete that sum, the result is on the price board, and the terms behind each figure are recorded in the seller write-ups. Where a seller does not publish enough, the honest state is no price rather than a flattering one, which is the rule the methodology sets out.