Peptide Dosing Calculator: Why Weight Matters

The Science Behind Weight-Based Dosing

When researchers study peptides, doses are almost always reported in micrograms per kilogram of body weight (mcg/kg). This isn't arbitrary — it's because the effective concentration of a peptide in your bloodstream depends on your total body mass.

Think of it like this: adding a teaspoon of salt to a cup of water produces a very salty solution. Adding that same teaspoon to a bathtub barely changes the taste. Your body works the same way — a larger body needs a proportionally larger dose to achieve the same blood concentration.

How We Calculate Doses

The basic formula is straightforward:

Total dose (mcg) = Body weight (kg) × Dose rate (mcg/kg)

For example, an 80 kg person taking BPC-157 at a standard rate of 5 mcg/kg:

• 80 kg × 5 mcg/kg = 400 mcg per injection

Understanding Dose Ranges

Most peptides have a range of studied doses rather than a single "correct" dose. Our calculator breaks these into three tiers:

Conservative (Low) Dose

The starting point. This is where you should begin, especially if:

• You've never used this peptide before
• You're sensitive to medications
• You want to assess tolerance before increasing

Standard (Medium) Dose

The most commonly referenced dose in research literature. This represents the "sweet spot" that most studies have found effective with manageable side effects.

Aggressive (High) Dose

The upper end of what has been studied. Higher doses don't always mean better results — many peptides have a ceiling effect where additional dose provides diminishing returns with increasing side effects.

Why Starting Low Matters

Individual responses to peptides vary enormously due to:

• Genetics — enzyme variants that affect metabolism
• Body composition — lean mass vs. fat mass distribution
• Receptor density — individual variation in receptor populations
• Existing conditions — health status affects clearance and sensitivity
• Other medications — potential interactions and competition for metabolic pathways

Starting at the low end and titrating up based on response is the safest approach. Our Dosage Calculator makes it easy to see all three dose tiers for your specific weight.

Common Dosing Mistakes

• Using flat doses regardless of weight — a 60 kg person and a 120 kg person should not take the same dose
• Starting at the highest dose — always titrate up from the lowest effective dose
• Changing doses too quickly — give each dose level at least 1-2 weeks to assess response
• Ignoring frequency — dose per injection and total weekly dose both matter
• Not tracking — keep a log of doses, timing, and effects to optimize your protocol

The Role of Frequency

Dosing isn't just about how much — it's also about how often. A peptide's half-life determines optimal frequency:

• Short half-life (BPC-157, Ipamorelin): Multiple daily doses maintain stable levels
• Medium half-life (TB-500): A few times per week is sufficient
• Long half-life (Semaglutide, CJC-1295 DAC): Once weekly maintains therapeutic levels

Use our Half-Life Visualizer to see how different frequencies affect your blood levels over time.