CommunityDosing & Titration

How do you calculate dosage after reconstituting?

27 replies12 peopleMay 28, 2026☆ Follow
Summary

how to figure out mg dose of retatrutide when reconstituting 20mg vial with 2.5ml water and injecting 30 units

The original poster is injecting 30 units from a 20mg vial mixed with 2.5ml water, which equals 2.4mg per week. Multiple replies walk through the basic math of concentration and confirm the dose while stressing the need to understand the calculation rather than rely solely on tools. Several users point out an initial miscalculation by one participant and recommend simpler reconstitution volumes for easier math. The thread ends with thanks for the explanations and general advice on starting low.

What this discussion establishesWhere people disagree

one participant initially stated the user was taking 9.6mg weekly and was corrected on the volume math

Nothing here is advice.

27 replies · 12 people
KeenHarbour73archiveopening postMay 28

I have been reading the forums and want to get my retatrutide dose right but the instructions are confusing. It says to mix 20mg powder with 2.5ml water and inject once a week. I am on my third week using 30 units in a small syringe. All the discussions here talk in mg so I need to know what my current intake actually is.

PatientTimber12archiveMay 28

There is a dosage calculator on one of the peptide info sites that should sort this out for you along with details on various compounds and their typical cycles.

PlainAlder11archiveMay 28

Sounds like you are aiming for 3mg. With 2.5ml added you actually need 38 units to hit that amount. If you had used 2ml then 30 units would have been exactly 3mg. It will still work for what you are doing though.

SharpAnchor92archiveMay 28

You have been taking 9.6mg of retatrutide each week. It seems risky to handle reconstitution without understanding the math or using calculators. Where did the retatrutide come from and what are you mixing it with?

LevelWillow41archiveMay 28

Who passed those directions along to you?

GreyLantern40archiveMay 28
↳ replying to @SharpAnchor92

No, the math needs another look before telling someone else they do not understand it. To take nearly half the vial he would need to inject nearly half the water volume which would be 125 units not 30.

LevelThistle44archiveMay 28
↳ replying to @KeenHarbour73 (opening post)

Forget the calculators and just learn the math because it is straightforward and lowers the chance of mistakes. Weight divided by volume gives concentration then multiply by the dose volume to get the weight delivered. So 20mg divided by 2.5ml is 8mg per ml and 0.3ml is 2.4mg. Or directly 20mg over 2.5ml times 0.3ml equals 2.4mg. The same approach works in reverse if you want a certain dose in a set volume.

LevelThistle44archiveMay 28

It is completely illogical in every respect.

GreyLantern40archiveMay 28

I get annoyed looking at the discussion. Anyone unsure of fundamental arithmetic ought to steer clear of baffling the novice.

SharpAnchor92archiveMay 28
↳ replying to @GreyLantern40

I stand corrected. I was in a sloppy hurry.

SlowBramble67archiveMay 28
↳ replying to @LevelThistle44

I know. I deleted my earlier response. I use a pen where 60 units equal 0.5ml but that does not apply to a syringe so I got mixed up at first then realized it right away.

SlowBramble67archiveMay 28
↳ replying to @GreyLantern40

What spot hurts you the most, in precise terms?

SlowBramble67archiveMay 29
↳ replying to @GreyLantern40

That is not related to the thread it is personal. You suffer from megalomania and there is not much hope but you could try kisspeptin at a high dosage to start.

CopperSignal27archiveMay 29

If you are not confident with the math then use an online peptide calculator. It is not safe to use these compounds without knowing your exact dose. Also for a 20mg vial use 2ml instead of 2.5ml so the numbers stay simple like 1mg per 0.1ml. Write the ratios out on paper and check them against a calculator to avoid mistakes.

KeenHarbour73archiveMay 30
↳ replying to @ClearBeacon24

Are all these calculators essentially the same?

KeenHarbour73archiveMay 30
↳ replying to @PlainAlder11

I still do not know my mg dose that is what I am trying to work out. These calculators should help.

KeenHarbour73archiveMay 30
↳ replying to @SharpAnchor92

Yeah, I see your point there. The same worry is what pulled me into checking out this spot. Someone I know through a mutual contact in healthcare passed along the peptides locally. They also provided the sterile water needed for mixing it up.

KeenHarbour73archiveMay 30
↳ replying to @LevelThistle44

Thank you. I am data driven and this is the insight I needed.

LevelTimber64archiveMay 30
↳ replying to @LevelThistle44

Thanks for this. I have looked at the math many times but never understood it until now. I have been relying on online calculators but it never felt right that I could not work it out myself.

PlainAlder11archiveMay 30
↳ replying to @KeenHarbour73

You have no clue how much you are taking? Start fresh with 2mg for four weeks then 4mg and adjust from there. I like four weeks because it lets the compound build up in the system but do whatever you want.

ClearHarbour45archiveMay 30

For 20mg add 1ml bac water so every 10 units is 2mg and every 5 units is 1mg. No need to fill the vial all the way. Before long you will be on 8mg which is 40 units. I do the same with 30mg vials so 10 units is 3mg. Keep it simple.

LevelWillow41archiveMay 31

Thank goodness you made it here and can learn how it is done.

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