Select a peptide to see its half-life, pharmacokinetic decay curve, recommended dosing frequency, and a visual 7-day dosing schedule. Understand how often to dose and when steady state is reached.
Choose from the dropdown to see half-life data, a pharmacokinetic decay curve, and a 7-day dosing schedule.
A peptide's half-life is the time it takes for its concentration in the blood to drop by exactly 50%. After two half-lives, 25% remains. After three, 12.5%. After five half-lives, less than 3.2% of the original dose is still circulating — which is why pharmacologists consider five half-lives the point at which a drug is essentially cleared.
Half-life determines dosing frequency. Short half-life peptides like Sermorelin (10–20 minutes) or GHK-Cu (approximately 10 minutes subcutaneously) need to be dosed daily to maintain meaningful levels. Long half-life peptides like Semaglutide (approximately 7 days) or CJC-1295 with DAC (approximately 8 days) can be injected once weekly because they persist in circulation far longer.
Steady state occurs when the amount of peptide entering the body equals the amount being eliminated, resulting in a consistent average concentration. It takes roughly 5 half-lives of consistent dosing to reach steady state. For a weekly semaglutide injection with a 7-day half-life, that means about 5 weeks. For BPC-157 dosed twice daily with a 4-hour half-life, steady state arrives within about 20 hours.
Understanding steady state matters because many peptides don't produce their full effects until this equilibrium is reached. This is why peptide cycling protocols typically recommend consistent dosing for several weeks before evaluating results.
Once you know how often to dose, you'll need to know how much to draw. Use our peptide reconstitution calculator to convert milligram doses into insulin syringe units. If you're combining multiple peptides, our peptide stacking guide covers timing, compatibility, and sequencing strategies.
Click any row to load the peptide in the calculator above. Half-life values are sourced from published pharmacokinetic studies where available.
| Peptide | Half-Life | Typical Frequency | Steady State |
|---|---|---|---|
| BPC-157 (subQ) | ~4 hours | 2x daily | ~20 hours |
| TB-500 | ~3 hours | 2x weekly (loading) | ~2 weeks |
| GHK-Cu (subQ) | ~10 minutes | 1-2x daily | ~50 minutes |
| Ipamorelin | ~2 hours | 1-3x daily | ~10 hours |
| CJC-1295 (no DAC) | ~30 minutes | 1-3x daily | ~2.5 hours |
| CJC-1295 (with DAC) | ~8 days | 1-2x weekly | ~6 weeks |
| Sermorelin | ~15 minutes | 1x daily (bedtime) | ~75 minutes |
| DSIP | ~7 minutes | 1x daily (bedtime) | ~35 minutes |
| Selank (nasal) | ~20 minutes | 2-3x daily | ~100 minutes |
| Semax (nasal) | ~20 minutes | 2-3x daily | ~100 minutes |
| AOD-9604 | ~22 minutes | 1x daily | ~2 hours |
| PT-141 | ~2 hours | As needed (min 24h gap) | N/A (as-needed) |
| Tirzepatide | ~5 days | 1x weekly | ~4 weeks |
| Semaglutide | ~7 days | 1x weekly | ~5 weeks |
| Retatrutide | ~6 days | 1x weekly | ~4.5 weeks |
| Epithalon | ~30 minutes | 1x daily (10-day cycles) | ~2.5 hours |
| KPV | ~1.5 hours | 1-2x daily | ~7.5 hours |
| Thymosin Alpha-1 | ~2 hours | 2x weekly | ~2 weeks |
| MOTS-c | ~3 hours | 3-5x weekly | ~1 week |
Weekly peptide research, pharmacokinetic updates, and practical dosing guidance — written for people who actually use peptides.