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Billed every 28 days: the 13th GLP-1 payment
A GLP-1 price "per month" and a price "per 28 days" look alike on a pricing page. Over a year they are not: one is paid 12 times, the other 13. This guide shows the arithmetic with prices read on October 15, 2026, and how to put any two programs on the same footing.
A program that bills every 28 days charges 13 times a year instead of 12, so a $239 cycle price costs $3,107 over a year rather than the $2,868 that twelve monthly payments suggest, an extra $239 that the headline hides. As of October 15, 2026, Found prices compounded tirzepatide per 28-day cycle, and Enhance.MD bills its plans every 4, 12, 24 or 48 weeks. NexLife and Eden quote prices per month. To compare fairly, multiply a cycle price by 13, or by 365 divided by the cycle length in days, before you set it beside a monthly price.
Why do GLP-1 programs bill every 28 days?
Because the medicine is weekly. Tirzepatide and semaglutide injections are taken once a week, so a box of four pens or a four-dose vial lasts 28 days, not a calendar month. Many programs bill per shipment, and a shipment is four doses. Fifty-two weeks divided by four is 13, so a patient who refills on time pays 13 times a year. A calendar-month price is paid 12 times.
Neither approach is wrong. The problem is comparison. A program that writes "$239/mo" for a 28-day cycle and a program that writes "$239/mo" for a calendar month are $239 apart over a year.
The same year, priced on different cycles
| Program and plan | Printed price | Cycle | Payments a year | Yearly cost | Per calendar month |
|---|---|---|---|---|---|
| Eden, tirzepatide | $129 | month | 12 | $1,548 | $129 |
| NexLife, tirzepatide, 12-month plan | $115 | month | 12 | $1,380 | $115 |
| Found, tirzepatide, 12-month plan | $239 | 28 days | 13 | $3,107 | $258.92 |
| Found, tirzepatide, month to month | $359 ($219 first) | 28 days | 13 | $4,527 | $377.25 |
| Enhance.MD, tirzepatide, 12-month plan | $280 | 4 weeks (billed every 48 weeks) | 13 | $3,640 | $303.33 |
| Enhance.MD, tirzepatide, 1-month plan | $329 | 4 weeks | 13 | $4,277 | $356.42 |
| Noom Med, tirzepatide (GLP-1Rx Plus) | $897 | 12 weeks | 4.33 | $3,887 | $323.92 |
| Wegovy pen, self-pay (NovoCare) | $349 | 4-dose fill (28 days) | 13 | $4,537 | $378.08 |
Arithmetic: yearly cost = printed price × payments in 52 weeks. Found month to month = $219 + 12 × $359 = $4,527 for 13 cycles. Enhance.MD bills its 12-month plan as one payment of $3,360 every 48 weeks (12 × $280); a full 52 weeks is 13 four-week cycles, $3,640. Noom = $897 × 52 ÷ 12 = $3,887. Per calendar month = yearly cost ÷ 12. Prices from each provider's own page, read 2026-10-15; Wegovy from NovoCare.
How do I convert a 28-day price to a monthly price?
Multiply by 13 and divide by 12, which is the same as adding 8.3%. If you want to be exact about the extra day in a year, multiply the cycle price by 365 and divide by the cycle length in days: a 28-day cycle is paid 13.04 times a year, a 30-day cycle 12.17 times and an 84-day (12-week) cycle 4.35 times.
- $239 per 28 days × 13 ÷ 12 = $258.92 per calendar month.
- $329 per 4 weeks × 13 ÷ 12 = $356.42 per calendar month.
- $897 per 12 weeks × 52 ÷ 12 ÷ 12 = $323.92 per calendar month.
Once every price is a calendar-month price, add any membership or program fee for the same period, and only then compare.
Worked examples
Example 1: Found against NexLife. Found's 12-month compounded tirzepatide plan is $239 per 28-day cycle and includes its care and membership. NexLife's 12-month plan is $115 per calendar month with no membership. Found's year is 13 × $239 = $3,107; NexLife's is 12 × $115 = $1,380. Read naively as "$239 vs $115 a month", the gap looks like $1,488 a year. The real gap is $1,727.
Example 2: the 48-week prepaid term. Enhance.MD's 12-month plan is billed every 48 weeks: $3,360 for twelve 4-week cycles. Forty-eight weeks is about 11 months, so the second charge arrives roughly a month before the first anniversary. If you budget "once a year", you will be four weeks early. Over a full 52 weeks the cost is $3,640.
Example 3: brand pens. NovoCare lists the Wegovy pen at $349 a month for self-pay (with a $199 introductory price on the first two fills of the lowest doses through December 31, 2026). A fill is four weekly doses, so a patient who refills every 28 days buys 13 fills: $4,537, not $4,188. The same applies to Zepbound through LillyDirect, where the $449 refill price for 7.5–15 mg becomes $5,837 over 13 fills.
The other 28-day rule: vial discard
There is a second "28 days" in GLP-1 care, and it affects cost too. FDA's consumer page on unapproved GLP-1 drugs (current as of October 1, 2026) tells patients to discard compounded multi-dose GLP-1 vials 28 days after first use. If a program ships one vial meant to last 8–10 weeks, and you follow that rule, the vial covers 4 weeks and the cost per month roughly doubles. Ask the program for the beyond-use date on the label; our beyond-use date guide explains what to look for.
A five-point check before you sign up
- Find the cycle. Look for "per 28 days", "every 4 weeks", "billed every 12 weeks" or "per shipment". If the page only says "/mo", ask whether that means a calendar month.
- Count the payments in a year. 12 for monthly, 13 for 28-day or 4-week, about 4.33 for 12-week cycles.
- Add the fees for the same period. A $75 monthly program fee is $900 a year whatever the medication cycle.
- Check the renewal date of prepaid terms. A "12-month" plan billed every 48 weeks renews about four weeks early.
- Check the dose. Many programs charge more at higher doses. A flat price at every dose, such as Eden's $129 or NexLife's $115 on 12 months, is the easiest to project; tiered prices need the dose you expect to reach.
What this means for you
If two prices are within about 8% of each other and one is per 28 days, they may be the same price. If they are further apart, the 28-day price is usually the more expensive one over a year. When you compare programs on this site, the price tables state the basis of each figure, and the true-cost calculator lets you enter the cycle length. Of the programs we re-read in October, Found and Enhance.MD bill in four-week units, Noom bills every 12 weeks, and NexLife and Eden quote calendar months.
Sources
- Found: compounded tirzepatide, prices per 28-day cycle (read 2026-10-15)
- Enhance.MD: advanced tirzepatide, billing every 4, 12, 24 or 48 weeks (read 2026-10-15)
- Noom Med: GLP-1Rx, billed quarterly (read 2026-10-15)
- Eden: GLP-1 weight loss pricing (read 2026-10-15)
- NexLife tirzepatide plans (read 2026-11-06)
- NovoCare: Wegovy self-pay offer (read 2026-10-15)
- LillyDirect Zepbound self-pay prices (archived 2026-09-30)
- FDA: Concerns with unapproved GLP-1 drugs used for weight loss (current as of 2026-10-01)
Related: October 2026 price changes · True Cost Index · how we normalise to a month.
Frequently asked questions
Is a price per 28 days the same as a monthly price?
No. A 28-day price is paid 13 times a year and a calendar-month price 12 times. To compare them, multiply the 28-day price by 13 and divide by 12, which adds about 8.3%. A $239 cycle price is $258.92 a calendar month.
Which GLP-1 telehealth programs bill every 28 days?
Of the programs we re-read on October 15, 2026, Found prices compounded tirzepatide per 28-day cycle and Enhance.MD bills in 4-week units (every 4, 12, 24 or 48 weeks). Noom bills its GLP-1 plans every 12 weeks. NexLife and Eden quote calendar-month prices.
Why would a 12-month plan renew before a year is up?
If it is billed as twelve 4-week cycles, the term is 48 weeks, about 11 months. The next charge then arrives roughly four weeks before the anniversary of your first payment. Check the renewal date and the cancellation notice period before you prepay.
Do brand-name GLP-1 pens also cost 13 payments a year?
Usually, if you refill on time. A pen box or fill holds four weekly doses, which last 28 days. The Wegovy pen at $349 per fill costs $4,537 over 13 fills a year rather than $4,188 for 12, using NovoCare's self-pay price read October 15, 2026.
Does the 28-day vial discard rule change my cost?
It can. FDA tells patients to discard compounded multi-dose GLP-1 vials 28 days after first use. If a program sells one vial as an 8–10 week supply, following that rule means buying more often, which can roughly double the monthly cost. Ask for the beyond-use date.