Half-Life Calculator
Visualize how compound blood levels change over time based on half-life and injection frequency.
Disclaimer
This tool is for education and research only and is not medical advice; results differ from person to person, so check every figure and talk to a healthcare professional before you act on anything here.
Blood levels differ with injection site, body composition, metabolism and carrier oil, so real levels may not match the chart.
Twice per week
Blood Concentration Over Time
Testosterone Cypionate: 250 mg every 3.5 days for 12 weeks
Key Metrics
Half-Life
10d
Time to Steady State
~7.1 wks
~5 half-lives
Peak at Steady State
1157.1 mg
Trough at Steady State
891.8 mg
Peak / Trough Ratio
1.30x
Very stable levels
Total Compound Used
6.0g
24 injections
Estimated PCT window
~34 days after last injection (Day 115)
This is when levels fall under 10% of peak (115.7 mg); the store's templates start PCT 2 weeks after the last long-ester shot.
Your last injection is on day 80.5; the cycle ends on day 84.
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.