If you’ve ever stared at a tiny peptide vial, a syringe, and a bottle of bacteriostatic water wondering “how much do I actually draw up?” — you’re not alone. Peptide dosing isn’t complicated once you understand the math, but one wrong decimal point can mean the difference between a precise dose and a wasted vial.
That’s where peptide calculators and tracking apps come in. Whether you’re reconstituting BPC-157 for the first time or managing a multi-peptide protocol with compounds like Retatrutide or CJC-1295, the right tools can save you time, reduce errors, and help you stay consistent.
This guide breaks down everything — from how reconstitution calculators work, to the best mobile apps for tracking your doses and protocols.
Free Tool
Peptide Reconstitution Calculator
Convert vial strength, water volume, and desired dose into precise syringe units. Works for BPC-157, TB-500, GHK-Cu, and all research peptides.
Try the Calculator →Why Peptide Calculators Matter
Peptides come as lyophilized (freeze-dried) powder in a vial. Before you can use them, you need to reconstitute them with bacteriostatic water (BAC water). The amount of water you add determines your concentration, which determines how much liquid you draw into the syringe for each dose.
Here’s a quick example. Say you have a 5mg vial of BPC-157 and you want to dose 250mcg. If you add 2mL of BAC water, your concentration is 2.5mg/mL (or 2,500mcg/mL). To get 250mcg, you’d need to draw 0.1mL — which is 10 units on a standard U-100 insulin syringe.
Simple enough in theory. But when you’re working with different vial sizes, different peptides at different doses, and different syringe types (U-100, U-40, U-30), the math gets layered fast. A calculator eliminates the guesswork entirely.
The Best Online Peptide Reconstitution Calculators
There are several solid free tools available right now. Here are the ones worth bookmarking.
PeptideCalc.io
PeptideCalc.io is one of the cleanest options out there. You enter your peptide amount (in mg), how much BAC water you’re adding, and your desired dose — it instantly gives you your syringe measurement. It also has an iOS app if you prefer mobile. The interface is minimal and the results are clear, which is exactly what you want when you’re mid-reconstitution.
PeptideScalculator.com
PeptideScalculator.com is another popular free tool. It walks you through the full process: vial amount, water volume, desired dose, and syringe type. It’s particularly beginner-friendly because it explains each field as you fill it in, so you understand why you’re drawing a certain number of units — not just what to draw.
PepDose
PepDose takes a slightly different approach by showing you the full picture at once: how much BAC water to add, your final concentration, and exactly how many units to draw for your desired dose. It’s fast, no sign-up required, and works well on mobile browsers.
PeptideFox AI Calculator
PeptideFox goes a step further with an AI-powered calculator that double-checks your math. If you’re newer to peptides or just want an extra layer of confidence, the automated verification is a nice touch. It handles reconstitution, dosing, and unit conversions.
When to Use an Online Calculator
Online calculators are ideal when you’re reconstituting a new vial or working with a peptide you haven’t used before. For example, if you’re trying Tesofensine capsules the dosing is straightforward, but when you’re reconstituting something like Ipamorelin or MK-677 in injectable form, a calculator makes sure you get the concentration right from the start.
The Best Peptide Calculator Apps (Mobile)
If you’d rather have everything on your phone — especially when you’re actually standing at your desk with a syringe in hand — these mobile apps are worth checking out.
PepCalc (iOS)
PepCalc is a no-frills calculator app that does one thing well. Enter your vial strength, BAC water volume, and desired dose — it gives you the syringe units instantly. Clean interface, no ads, no account required. It also handles the reverse calculation: figuring out how much BAC water to use for a target concentration.
Peptide Calculator App (Android)
The Peptide Calculator App on Google Play includes a BAC water calculator, supports multiple syringe types (U-20, U-30, U-40, U-100), and even has a blend calculator for mixing multiple peptides into a single vial. That last feature is particularly useful if you’re running a stack — say CJC-1295 and Ipamorelin together in one reconstitution.
Peptide Tracking and Logging Apps
Calculators handle the math, but what about everything else? When did you last dose? Which injection site did you use? How many doses are left in this vial? Are you on the right day of your protocol? That’s where tracking apps come in — and the peptide app space has exploded recently.
PepTracker
PepTracker is built specifically for GLP-1 and peptide tracking. You can create structured protocols, schedule injections, calculate syringe volumes, and keep a detailed record of your progress — all in one app. It supports popular peptides like Semaglutide, Tirzepatide, and Retatrutide, and it handles multi-compound stacks well. If you’re running a protocol with TB-500 for recovery alongside a GLP-1 compound, PepTracker keeps everything organized.
SHOTLOG
SHOTLOG (available on both iOS and Android) is one of the most popular options right now. It lets you create custom protocols for any peptide, has a built-in calculator that converts between mg, mcg, and IU instantly, and supports one-tap dose logging with automatic injection site rotation. The reminder system is solid too — no more forgetting your evening dose of GHK-Cu.
Peptide Log
Peptide Log stands out with its concentration curve modeling. It offers different models depending on whether you’re using a long-acting peptide (like weekly Semaglutide) or a fast-acting one (like BPC-157 or TB-500). Being able to visualize how your peptide levels rise and fall over time adds a layer of understanding that most apps don’t offer.
PeptIQ
PeptIQ is tailored toward GLP-1 peptides specifically — Semaglutide, Tirzepatide, Retatrutide, and newer compounds. It tracks weekly doses, titration schedules, weight trends, and side effect patterns. If weight management is your primary goal and you’re using something like 5-Amino-1MQ or MOTS-C alongside a GLP-1, PeptIQ helps you see the full picture.
Peptide Library (Android)
Peptide Library is the most comprehensive Android option. It combines a peptide guide, an advanced dose calculator, a lab inventory tracker, protocol management, and even an amino acid calculator. Think of it as a one-stop research toolkit on your phone.
How to Choose the Right Tool
It depends on where you are in your peptide journey.
Just starting out? Use an online calculator like PeptideScalculator.com — it walks you through every step and explains the logic. Pair it with a simple tracker like SHOTLOG so you don’t lose track of your doses.
Running a multi-peptide protocol? You’ll want a dedicated tracking app. PepTracker or SHOTLOG handle stacks well, and the Peptide Calculator App on Android supports blend calculations for multi-vial reconstitution.
Focused on GLP-1s and weight management? PeptIQ is purpose-built for that. Combine it with compounds from Prax Peptides like Retatrutide or Tesofensine and you have a solid system for tracking your progress.
Want everything in one place? Peptide Library on Android comes closest to an all-in-one solution with its calculator, tracker, inventory management, and research database combined.
Quick Tips for Accurate Peptide Dosing
No matter which tools you use, keep these fundamentals in mind.
Always use bacteriostatic water — not sterile water, not saline. BAC water contains a small amount of benzyl alcohol that prevents bacterial growth, keeping your reconstituted peptide safe for multiple draws over days or weeks.
Store reconstituted peptides in the fridge. Once you’ve mixed your vial, it should stay refrigerated (2-8°C / 36-46°F). Most reconstituted peptides stay stable for 3-4 weeks when stored properly.
Use insulin syringes for precision. U-100 insulin syringes are the standard for peptide dosing. They’re cheap, widely available, and the fine gauge needles make subcutaneous injection comfortable.
Double-check your math the first time. Even with a calculator, verify your numbers once manually. After you’ve done it a few times, it becomes second nature — but that first reconstitution deserves extra attention.
Log everything. Whether it’s an app or a notebook, recording your doses, timing, injection sites, and any effects helps you optimize over time. The data compounds (no pun intended).
Final Thoughts
The peptide space has matured significantly. A couple of years ago, you’d be doing math on the back of a napkin or trusting a random forum post. Now there are purpose-built calculators, professional tracking apps, and real tools designed to make dosing accurate and consistent.
If you’re sourcing quality peptides, Prax Peptides carries a full range — from research staples like BPC-157 and GHK-Cu to newer compounds like Retatrutide and Kisspeptin-10. Pair them with the right calculator and tracking app, and you’ve got a system that’s precise, organized, and easy to maintain.
The tools are there. Use them.