---
title: "When to Start Your PCT After a Steroid Cycle"
description: "When to start PCT based on your last injection and ester half-life: the time-on equals time-off principle."
lang: en
dateModified: 2026-05-23
canonical: https://anaprotokol.com/en/guides/when-to-start-pct
---

# When to Start Your PCT After a Steroid Cycle

The **delay before starting PCT** is one of the two or three parameters that on their own decide whether a restart succeeds or fails — on the same level as the choice of SERM and its dose. Start too early, and the SERMs are working in an environment still saturated with exogenous testosterone: the brain does not catch the signal and the restart never takes off. Start too late, and you drag out the post-cycle hypogonadism window for nothing.

This guide lays out the math: based on the half-life of the longest ester (or compound) in the cycle, at what point residual serum levels drop low enough for SERMs to actually act. For the PCT protocols themselves, see the pillar [PCT protocol guide](/en/guides/pct-protocol-guide). For the broader context on cycle length and off-time, see [short vs long cycle](/en/guides/short-vs-long-steroid-cycle).

## The principle: wait until residual levels drop

A compound's half-life is the time it takes for its blood concentration to drop by half. After an injection, concentration follows an exponential decay. As a practical rule, after 4 to 5 half-lives, the residual concentration is around 3 to 6% of the initial serum level — that is the threshold at which there is no longer enough peripheral signal to block central signaling [1].

The [half-life calculator](/en/calculators/half-life) lets you visualize that decay day by day for a given compound. It is the concrete tool to pinpoint your PCT start — more reliable than a rough rule picked up on a forum.

> The "5 half-lives" logic gives you a benchmark, not an absolute truth. Individual sensitivity, the accumulated dose during the cycle and the cycle duration all add a margin of uncertainty. Best bet: aim at the higher end of the window when the cycle was long or suppressive.

## Standard delays by ester

| Compound | Half-life | Delay after last injection |
| --- | --- | --- |
| Testosterone propionate | 2 days | 3 to 5 days |
| Testosterone enanthate | 4.5 days | ~ 2 weeks |
| Testosterone cypionate | 5 days | 2 to 2.5 weeks |
| Trenbolone acetate | 1 day | 3 to 5 days |
| Trenbolone enanthate | 5 days | 2 to 3 weeks |
| Masteron enanthate | ~ 4 to 5 days | 2 weeks |
| Nandrolone decanoate (Deca) | 6 days | 3 weeks, sometimes longer on long cycles |
| Boldenone undecylenate (EQ) | 14 days | 3 to 5 weeks, sometimes longer |
| Sustanon (ester mix) | ~ 8 days (longest ester) | 2.5 to 3 weeks |

These delays are standard starting points, calibrated against the published half-life for each compound on AnaProtoKol's compound pages (see for example the [testosterone enanthate](/en/molecule/test-enanthate) or [nandrolone decanoate](/en/molecule/nandrolone-deca) pages). On a multi-compound cycle, the longest compound dictates the timing [3] — not testosterone if you stacked deca on top.

## Multi-compound cycles: pin against the longest

Typical setup: a cycle combines several esters with different half-lives. Starting PCT against testosterone when you ran deca for 16 weeks means starting while nandrolone (half-life 6 days, very long residual after a long cycle) is still fully blocking the HPTA [2].

### Examples

- **Test E + Masteron E (12 weeks)**: both have very close half-lives (4 to 5 days). PCT about 2 weeks after the last injection.
- **Test E + Tren A (10 weeks, Tren A dropped 2 weeks before the end)**: enanthate dictates. PCT 2 weeks after the last Test E injection.
- **Test E + Deca (14 weeks, simultaneous stop)**: nandrolone decanoate dictates. PCT 3 weeks after the last injection, sometimes longer depending on cumulative dose.
- **Test E + Boldenone (16 weeks, simultaneous stop)**: boldenone (half-life 14 days) dictates. PCT 3 to 5 weeks after the last injection.

### Classic strategy: drop the long compound early

To avoid stretching the gap between last injection and PCT excessively, a common practice is to drop the longest compound a few weeks before cycle end and finish on a shorter compound (for example, finishing a deca cycle with two weeks of testosterone propionate alone). PCT can then start earlier, pinned against the short ester — provided the long compound had time to drop. Cycle structure detail in [how to design a steroid cycle](/en/guides/how-to-design-a-steroid-cycle).

## And after PCT: "time on = time off"

The delay before PCT is only one piece of the calendar. Once PCT wraps (4 to 6 weeks of SERMs depending on the protocol), a gear-free window — the 'off-period' — must at minimum match the cycle duration. That is the largely consensual 'time on = time off' rule, which gives the HPTA enough time to functionally recover [4].

### Sample full calendar (12-week enanthate cycle)

- Weeks 1 to 12: testosterone enanthate cycle.
- Weeks 13 to 14: wait before PCT (~ 2 weeks after the last injection).
- Weeks 15 to 18: PCT (4 weeks of Nolvadex 40/40/20/20).
- Week 22 to 24: follow-up post-PCT blood panel (4 to 6 weeks after the last Nolvadex dose).
- Weeks 19 to 30: off-period (~ 12 weeks, to validate via the post-PCT bloods).
- Total: ~ 30 weeks between the first injection and the start of any eventual next cycle.

> Cutting the off-period short means starting the next cycle on an un-recovered axis. It is the first step on the slope toward [blast and cruise](/en/guides/blast-and-cruise-explained) — which is not a shortcut but a distinct lifestyle choice (permanent TRT in practice).

## The most common timing mistakes

- **Starting PCT the day after the last long-ester injection**: levels are still at plateau. SERMs spin in a vacuum for 1 to 2 weeks.
- **Pinning PCT against testosterone when the cycle included long deca**: residual nandrolone blocks everything. Result: recovery that looks like it is failing, panic, sometimes a return to gear "to feel better".
- **Confusing half-life with clinical effect duration**: a compound stops having 'full' effect well before 5 half-lives, but holds central suppression up to that point. What matters for PCT is suppression — not how you feel.
- **Wanting to start PCT "to be safe" very early**: it speeds up nothing and burns SERM with no benefit. A well-timed, well-dosed PCT beats a too-long, poorly-positioned one.

The concrete tool to pinpoint the right start stays the [half-life calculator](/en/calculators/half-life), applied to the longest compound in the cycle. And for the ester mechanics in detail, see [steroid esters explained](/en/guides/steroid-esters-explained).

## FAQ

### Why exactly 2 weeks after the last enanthate?

It is a practical approximation: 2 weeks works out to about 3 half-lives of enanthate (4.5 days × 3 = 13.5 days). Residual levels are then around 12% of the initial level — close to the threshold where central suppression fades and SERMs can act effectively. An extra margin is legitimate if the cycle ran longer than 14 weeks or the dose was high.

### Does the delay change if the cycle dose was high?

Slightly, yes. A high dose on a long cycle produces tissue accumulation and a higher serum level at the time of the last injection. The time needed to drop under the SERM-useful threshold is therefore a bit longer. Not by several weeks, but by a few extra days on the high end of the table. Conversely, for a contained dose on a short cycle, the low end of the table is enough.

### Should you get bloods before PCT to confirm levels dropped?

In the vast majority of cases, no — the half-life calculation is enough. The critical blood panel is the one done 4 to 6 weeks after PCT ends to confirm recovery (LH, FSH, testosterone, estradiol). A pre-PCT panel can have value after a particularly long and suppressive cycle, or when stepping out of an extended blast, to confirm exogenous signal has cleared — but those are edge cases. See [blood test schedule on cycle](/en/guides/blood-test-schedule-cycle).