Let's talk about half-lives

Just wanted to give a refresher to some and maybe there are those out there who don’t fully understand the concept of half-life.

First thing, what does half-life mean?

Let’s say a compound has a half-life of 7 days. What this means is that 7 days after administration there will be half of the compound left in the system. So does that mean in 14 days it’s out of your system? NO!

In an additional 7 days, 50% of what’s left will still be in your system. So, if you take 100mg, 7 days later there will be 50mg left. In another 7 days, or 14 days after administration, 25mg will be left in your system. In another 7 days, or 21 days later, 12.5mg will be left in your system. In another 7 days, or 28 days later, 6.25mg will be left in your system. So you can see that compounds remain in your system for quite some time.

Also, there is conflicting data on half-lives as well. So you may read in one place that something has a 5 or 6 day half life and somewhere else it might 7…

Here are some of the most popular compounds and their respective half-lives:

Oral steroids Drug Active half-life
Anadrol / Anapolan50 (oxymetholone) 8 to 9 hours
Anavar (oxandrolone) 9 hours
Dianabol (methandrostenolone, methandienone) 4.5 to 6 hours
Winstrol (stanozolol) (tablets or depot taken orally) 9 hours

Depot steroids Drug Active half-life
Deca-durabolin (Nandrolone decanate) 14 days
Equipoise 14 days
Finaject (trenbolone acetate) 3 days
Primobolan (methenolone enanthate) 10.5 days
Sustanon or Omnadren 15 to 18 days
Testosterone Cypionate 12 days
Testosterone Enanthate 10.5 days
Testosterone Propionate 4.5 days
Testosterone Suspension 1 day
Winstrol (stanozolol) 1 day

Steroid esters Drug Active half-life
Formate 1.5 days
Acetate 3 days
Propionate 2 days
Phenylpropionate 4.5 days
Butyrate 6 days
Valerate 7.5 days
Hexanoate 9 days
Caproate 9 days
Isocaproate 9 days
Heptanoate 10.5 days
Enanthate 10.5 days
Octanoate 12 days
Cypionate 12 days
Nonanoate 13.5 days
Decanoate 15 days
Undecanoate 16.5 days

Ancillaries Drug Active half-life
Arimidex 3 days
Clenbuterol 1.5 days
Clomid 5 days
Cytadren 6 hours
Ephedrine 6 hours
T3 10 hours
Letrozole 5 hours
Nolvadex (Tamoxifen Citrate) 14 days
Viagra (Sildenafil) 3-5 hours
Cialis (Tadalafil) 17.5 hours
Caber 2.5 days


Nice post Rambo :facepunch:t2: The most confused topic and misunderstood around.


Nice read and info. I didn’t know adex or nolva was active that length


I was just looking for the Nolva half-life. Thank you :pray:t3:


Me trying explain my dosing calendar.


Definitely a very good breakdown of half life’s and how to track.

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Great post and information brother

Added Caber to the list

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Just about E3D. This info is invaluable. Should be part of anyones cycle prep.


Yes sir… I know when I started out on this journey I didn’t understand or fully grasp it so I hoped this would help someone out.

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I’m just going to add that the reason we measure half lives is to approximate when it’s OK to take the next dosage — usually with other medications (other than anabolics) that we’re trying to keep at a stable level inside the body

It’s useful for anabolics because the whole point of cycles is to keep levels above the activation threshold “forever**”

**not actually forever

It also generally allows for covering requirements of both slow and fast metabolizers

A “therapeutic dosage” is one designed to match normal levels in the human body, meaning 200+ mg / week is NOT one since the average male produces 42-49 mg / week

(You might need therapeutic dosages for thyroid or pancreatic problems and you would have to calculate that out of your cycle, for example)