Free · No Account · Any Peptide

Peptide
Reconstitution
Calculator

Three inputs. Four outputs. The math that determines every dose — calculated in under a second. Custom Draw mode inverts the formula: specify your draw, get the BAC water amount.

Full suite with PK plotter, TRT ester, stack cost:
reconstitution.health  ·  Protocol app

Calculator

2,500
mcg/mL
10
Draw Units
0.10
Draw (mL)
20
Doses/Vial

U-100 syringe. Draw to marked unit on syringe.

How It Works

The Reconstitution Formula

A peptide reconstitution calculator takes three inputs and derives four outputs through two sequential formulas. Input: vial size in mg (converted to mcg internally), bacteriostatic water volume in mL, and target dose in mcg. Output: concentration in mcg/mL, syringe draw units for a U-100 syringe, draw volume in mL, and doses per vial.

Standard mode: Concentration = (Vial mg × 1,000) ÷ BAC water mL  ·  Draw units = (Dose mcg ÷ Concentration) × 100

Custom Draw mode: BAC water = (Vial mg × 1,000) ÷ [(Draw units ÷ 100) × 1,000 ÷ Dose mcg]

Custom Draw is available in both this calculator and at reconstitution.health. It's the only free web calculator with this feature — Protocol's app (iOS + Android) also includes it.

Reference

Common Configurations

VialBAC WaterConcentration250mcg500mcg1mg
5mg2mL2,500 mcg/mL10 units20 units40 units
5mg4mL1,250 mcg/mL20 units40 units80 units
10mg4mL2,500 mcg/mL10 units20 units40 units
2mg1mL2,000 mcg/mL12.5 units25 units50 units
2mg2mL1,000 mcg/mL25 units50 units—

Highlighted draws are 10–25 units — optimal accuracy range on a U-100 insulin syringe.

FAQ

Calculator Questions

What is Custom Draw mode?
Custom Draw reverses the standard reconstitution calculation. Instead of entering BAC water and getting draw units as output, you specify the draw units you want per dose as input and the calculator returns the BAC water volume that produces exactly that draw. It's useful when you want a specific draw unit (say, 20 units) for ease of measurement and want to build the reconstitution around that target.
What is a U-100 syringe?
A U-100 insulin syringe holds 1mL and is graduated in 100 units (1 unit = 0.01mL). It's the standard for subcutaneous peptide injections. When this calculator shows "draw units," it means the graduation marking on a U-100 syringe to fill to. Never use a U-40 syringe with U-100 calculations.
Does this calculator work for semaglutide and tirzepatide?
Yes. The calculator works for any lyophilized compound requiring reconstitution — including compounded semaglutide and tirzepatide. Enter the vial size (mg), BAC water volume (mL), and target dose (mcg) for any GLP-1 compound. Custom Draw mode is useful during GLP-1 titration when vial sizes change but you want a consistent draw unit per injection.
Where is the full peptide calculator suite?
The full suite — Custom Draw, PK half-life plotter for 22 compounds, TRT ester calculator, and stack cost calculator — is at reconstitution.health (web, no download) and in the Protocol app (free on iOS and Android at protocolapp.health).

Full Suite: Five Calculators Free

Custom Draw · PK Plotter · TRT Ester · Stack Cost · iOS + Android

App Store Google Play

No account · On-device · iOS + Android · Also at reconstitution.health