Half-Life Calculator
Visualize how compound blood levels change over time based on half-life and injection frequency.
⚠️ Disclaimer
This tool is for educational and research purposes only. Pharmacokinetics vary between individuals based on injection site, body composition, metabolism, and carrier oil. Actual blood levels may differ.
Twice per week
Blood Concentration Over Time
Testosterone Cypionate — 250mg every 3.5 days for 12 weeks
Blood level Steady state Last injection PCT window
Key Metrics
Half-Life
10d
Time to Steady State
~7.1 wks
~5 half-lives
Peak at Steady State
648.4 mg
Trough at Steady State
399.1 mg
Peak / Trough Ratio
1.62x
Moderate fluctuation
Total Compound Used
6.3g
25 injections
PCT Start Recommendation
~27 days after last injection (Day 111)
When blood levels drop below 10% of peak (64.8 mg)
How to Read This Chart
- •Each spike represents an injection adding to your blood level. The compound then decays based on its half-life until the next injection.
- •Steady state is reached after ~5 half-lives. At this point, the amount leaving your system equals the amount being injected.
- •A lower peak/trough ratio means more stable blood levels. Injecting more frequently reduces fluctuation.
- •The PCT window marks when compound levels are low enough (<10% of peak) that recovery protocols can begin effectively.