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ForumsDosing & ProtocolsMath is hard - help me with reconstitution please Page 2

Math is hard - help me with reconstitution please

WendyG_ATL Sun, Feb 8, 2026 at 10:05 PM 13 replies 656 viewsPage 2 of 3
zoe_NC
Member
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1,234
Nov 2024
Charlotte, NC
Feb 9, 2026 at 12:55 AM#6

Wait I'm confused. My vial says 3mg not 5mg. Do I just use the same formula?

49 8Dr.BariatricHTX, LindaRN_retired, tommy_boulder and 46 others
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NicoleRaleigh
Member
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1,567
Aug 2024
Raleigh, NC
Feb 9, 2026 at 1:12 AM#7
Previously posted:
My vial says 3mg not 5mg. Do I just use the same formula?

Same exact formula, just different numbers. The universal formula is:

Volume to inject (mL) = Desired dose (mg) ÷ Concentration (mg/mL)

And concentration = Total mg in vial ÷ mL of BAC water added

So for your 3mg vial, if you add 1.5mL BAC water:

  • Concentration = 3mg / 1.5mL = 2mg/mL
  • 0.25mg dose = 0.25 / 2 = 0.125mL = 12.5 units (draw to halfway between 10 and 15)
  • 0.5mg dose = 0.5 / 2 = 0.25mL = 25 units

Or if you want easier numbers, add 1.2mL BAC water to get 2.5mg/mL, then 0.25mg = 10 units. Same as the 5mg vial example. The total number of doses per vial will be different of course (3mg total instead of 5mg).

31 19MikeFit_NJ, InsuranceTom, WendyG_ATL and 28 others
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VendorMark
Senior Member
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14,567
Jan 2024
Texas
Online
Feb 9, 2026 at 1:29 AM#8

you are an absolute angel. I just did my first reconstitution and injection — 10 units, right in the belly, barely felt it. This community is the best. Thank you all so much!! 🙏🥹

19 10MarkLI_maint, Dr.PeteFamMed, claudia_zurich and 16 others
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MounjBrad
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278
890
Oct 2024
Kentucky
Feb 9, 2026 at 1:46 AM#9

Pinning this thread. We get this question at least twice a week. Excellent explanations as always from our knowledgeable members. For anyone reading this in the future, we also have a reconstitution calculator in the Tools section of the wiki.

And a reminder: always verify your math before injecting. If something seems off, ask here or call your provider. It's never a dumb question when it comes to dosing.

11 0pam_columbus, nick_SD_fit, ben_calgary and 8 others
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