How does the PCT Start-Date Calculator work?

The calculator uses the half-life of your compound to determine when approximately 97% of the substance has cleared your system (roughly 3-4 half-lives). This is the point where your HPTA can begin responding to SERMs effectively.

Why can't I start PCT immediately after my last injection?

SERMs work by tricking the pituitary gland into producing LH and FSH. If synthetic testosterone is still active in your system, the body won't respond to that signal. You need to wait for the exogenous compound to clear before SERMs can be effective.

How long after Testosterone Enanthate should I start PCT?

Testosterone Enanthate has a half-life of approximately 4.5-7 days. The recommended wait time is 14-18 days after your last injection before beginning your SERM protocol.

PCT Start-Date Calculator - When to Begin Post Cycle Therapy

Compound Half-Life Reference

This table shows the commonly accepted half-lives and recommended PCT start windows. The calculator uses the formula: Start Date = Last Injection + (Half-Life x 3.5), which targets the point where the compound is roughly 90-97% cleared.

Compound	Half-Life	Recommended PCT Start
Testosterone Propionate	~0.8-2 days	3-5 days after last shot
Testosterone Enanthate	~4.5-7 days	14-18 days after last shot
Testosterone Cypionate	~8 days	18-21 days after last shot
Nandrolone Decanoate (Deca)	~12-15 days	21-30 days after last shot
Oral Steroids (Dbol, Anadrol)	~4-8 hours	1-3 days after last dose
SARMs (Ostarine, RAD-140)	~16-24 hours	1-3 days after last dose

Why Timing Matters

SERMs work by blocking estrogen receptors in your pituitary gland, which tricks it into ramping up LH and FSH production. But here's the thing - if there's still a significant amount of synthetic testosterone floating around in your bloodstream, your body won't respond to that signal. The exogenous hormones override everything.

That's why you need to wait for the compound to clear before starting your SERM protocol. Start too early and you're wasting your PCT drugs. Start too late and you've spent unnecessary days in a suppressed, low-hormone state where cortisol is eating your gains.

The "sweet spot" is typically around 3 to 4 half-lives after your last dose. At that point, roughly 90-97% of the compound has cleared, and your HPTA is ready to respond to SERM stimulation.

Calculator FAQ

It multiplies your compound's half-life by 3.5 to estimate when ~90-97% of the substance has cleared your system. That's the window where your HPTA can begin responding to SERMs effectively.

If synthetic testosterone is still active in your system, SERMs won't work properly. Your body's feedback loop needs to "see" low androgen levels before it'll restart natural production. Starting early just wastes your PCT compounds.

Always base your PCT timing on the compound with the longest half-life. If you ran Test-E and Deca together, you'd time your PCT based on Deca's 12-15 day half-life, not Test-E's shorter one.

No. This gives you a solid starting estimate, but bloodwork is always the gold standard. If possible, get your levels checked before starting PCT to confirm your exogenous hormones have actually cleared.