Calculator Guide

How a Peptide Calculator
Actually Works

Three inputs. Four outputs. One formula. The math takes 30 seconds — but only if you're using the right inputs in the right order.

The Core Formula

Three Inputs, Four Outputs

Vial
Peptide amount in mg or mcg
BAC
Bacteriostatic water in mL
Dose
Target dose in mcg

Enter these three values and a calculator returns: concentration (mcg/mL), syringe draw units for a U-100 syringe, draw volume in mL, and total doses per vial. Every output flows from the concentration — get the BAC water volume right and everything else is arithmetic.

The formula

Concentration = Vial mcg ÷ BAC water mL
Draw units = (Dose mcg ÷ Concentration) × 100

Example: 5mg vial (5,000mcg) + 2mL BAC water = 2,500 mcg/mL. For 250mcg dose: (250 ÷ 2,500) × 100 = 10 units on a U-100 syringe. For 500mcg: 20 units. This is the full calculation — nothing more complex than division and multiplication by 100.

The Input That Drives Everything

Why BAC Water Volume Is the Critical Variable

Vial size and dose are fixed — the peptide determines the vial, your protocol determines the dose. The only variable you control is how much bacteriostatic water you add. That choice determines your concentration, which determines your syringe draw for every dose you take from that vial.

Add more BAC water: lower concentration, higher draw units (easier to read on a small syringe). Add less: higher concentration, lower draw units (harder to measure accurately below 5 units). The practical recommendation: choose a BAC water volume that gives you 10–20 units per dose. Sub-5-unit draws introduce too much measurement error on a U-100 insulin syringe. Above 40 units, you're drawing from a large portion of the syringe and may want to use a larger vial or higher concentration.

Protocol's Custom Draw mode inverts this calculation — you specify the syringe units you want per dose, and it calculates the BAC water volume that produces exactly that draw. No other free calculator has this mode. Try it at reconstitution.health.

Common Inputs

Reference Table — Standard Vial Sizes

VialBAC WaterConcentration250mcg Draw500mcg Draw
5mg2mL2,500 mcg/mL10 units20 units
5mg4mL1,250 mcg/mL20 units40 units
10mg2mL5,000 mcg/mL5 units10 units
10mg4mL2,500 mcg/mL10 units20 units
2mg1mL2,000 mcg/mL12.5 units25 units

All draws are for U-100 insulin syringes (100 units = 1mL). Highlighted draws are in the 10–25 unit range — easiest to measure accurately.

FAQ

Common Questions

What is the difference between mg and mcg in peptide calculations?
1mg = 1,000mcg. Vials are typically labeled in mg (2mg, 5mg, 10mg) and doses are described in mcg (250mcg, 500mcg). Enter the vial size converted to mcg — a 5mg vial is 5,000mcg — and enter the dose in mcg. Most calculators handle this automatically but it's worth verifying which unit your calculator expects.
What is a U-100 syringe?
A U-100 insulin syringe holds 100 units per 1mL of liquid. It's the standard for peptide dosing. The graduation marks on the syringe represent units from 0–100 (or 0–50 for a half-unit syringe). When a calculator gives you a "draw units" result, it means the marking on a U-100 syringe to fill to. Do not use a U-40 syringe with U-100 math — it produces a 2.5× dosing error.
Can I change my BAC water volume mid-vial?
No. Once you've reconstituted, the concentration is fixed. Adding more BAC water to a reconstituted vial would change the concentration for all remaining doses — and you'd have no reliable way to know exactly how much was added versus what's already been drawn. Always calculate before reconstituting and commit to one BAC water volume per vial.

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