Most peptide calculators are anonymous web pages with no company behind them, no explanation of the math, and no way to know if the output is right. That’s a problem when the difference between milligrams and micrograms is a 1000x dosing error.
I went through every tool I could find and ranked them by one standard: would I trust this before drawing a syringe? Here’s what I actually think.
1. FormBlends Peptide Calculator
This one earns the top spot for a specific reason. It shows the math.
Most calculators spit out a number. You accept it on faith. FormBlends shows you the concentration step and the unit conversion step so you can follow along and catch an error if something looks wrong. That transparency matters when you’re working with compounds dosed in micrograms.
The tool is free, requires no account, and lives both as a standalone web page and inside the FormBlends mobile app for iOS and Android. You enter three things: the total peptide in the vial, how much bacteriostatic water you added, and the dose you’re targeting per injection. It outputs the concentration per mL, the exact units to draw on an insulin syringe, and the total number of doses you’ve got.
A few things make this one genuinely different from the pack. It handles U-100, U-50, and U-40 syringes. It converts mg to mcg automatically, which removes what is honestly the most dangerous single mistake in peptide prep. There is a visual syringe fill bar so you can see where your plunger lands, not just read a number. And it includes one-tap presets for common compounds, BPC-157 at 5 mg and 10 mg, TB-500 at 5 mg, ipamorelin at 10 mg, tesamorelin at 2 mg, and a GLP-1 option at 50 mg.
The company behind it runs a 503A compounding pharmacy. That’s not a guarantee of accuracy, but it means there’s an actual organization with accountability attached to this tool, which puts it in a different category from a random calculator with no author listed.
One honest caveat worth stating clearly: the tool does not suggest a dose. You enter the dose you’ve been given by a provider, and it tells you how to measure it. It’s a measurement aid. That’s the right scope for something like this.
The mobile app adds dose logging, injection-site rotation tracking, and a 55-compound reference library. For anyone doing multi-peptide protocols, that’s where the real value sits.
2. PeptideFox
PeptideFox at peptidefox.com covers more than 30 individual peptides, which is the widest compound list I’ve seen from a single web tool. The feature I keep coming back to is BAC water volume optimization. It suggests a water amount that puts your target dose at a clean, round number of units on a U-100 syringe. That’s a genuinely useful idea. Drawing 23 units is less error-prone than drawing 17.4 units. There’s also a visual guide. Worth bookmarking.
3. MyPeptideMatch
Free, no account needed, and covers BPC-157, semaglutide, tirzepatide, TB-500, and a handful of other injectables. The GLP-1 coverage is what makes it stand out. Semaglutide and tirzepatide reconstitution catches people off guard because the vial sizes and dose increments work differently than healing peptides. Having a dedicated tool that handles both categories in one place is useful. Simple interface, nothing fancy.
4. PeptideDeck
You input the vial size in milligrams, the BAC water volume in mL, and the dose you want in micrograms. It gives you the concentration, the draw volume in mL, and the draw in insulin units. Clean and direct. No frills at all. The fact that it outputs both mL and units is good because some people think in one unit and some think in the other.
5. LeadWest Medical Calculator
This one covers a specific and somewhat unusual list: retatrutide, BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, sermorelin, and GHK-Cu. Retatrutide is newer than most tools bother to include. If you’re working with a protocol that includes sermorelin or CJC-1295 alongside a healing peptide, having them under one roof without switching tabs is worth something.
6. Outliyr Peptide Calculator
Outliyr covers BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, GHK-Cu, and GLP-1 class compounds. The site has a health optimization bent and tends to include context around the compounds rather than just the math. That extra context is good for someone new to reconstitution who wants to understand what they’re doing, though it can feel like a lot of reading when you just want the numbers.
7. peptidereconstitutecalculator.com
Narrow focus: BPC-157 specifically. It converts micrograms to units on a U-100 syringe and does that one thing cleanly. Because U-100 means 100 units per 1 mL, a 500 mcg dose from a 5 mg vial reconstituted in 2 mL works out to a specific unit draw, and this page handles that math without making you think about it. If BPC-157 is the only thing you’re calculating, this is fast.
8. Prime Peptides Calculator
Available through the Prime Peptides website. Functional reconstitution calculator, covers the standard inputs and outputs. Useful as a quick cross-check. The backing brand is a known vendor in the research peptide space, which is at least traceable, though I’d treat any vendor-hosted tool as a second opinion rather than a primary reference.
9. peptides.org Dosage Charts
Not a calculator in the interactive sense, but dosage reference charts that show typical ranges for a wide list of compounds. Most useful for understanding the ballpark before you sit down with a calculator. Knowing that healing peptides like BPC-157 and TB-500 are commonly dosed somewhere between 250 and 500 mcg helps you sanity-check any output before you draw.
One Thing True of Every Tool Here
Adding more bacteriostatic water to a vial changes the number of units you draw per dose. It does not change how much peptide is in each dose. That distinction confuses people constantly, and understanding it makes every calculator on this list easier to use correctly.
A Word Before You Use Any of These
None of these tools prescribe a dose, and neither do I. If you’re working with injectable compounds, a qualified medical provider should determine your protocol. A calculator’s job is to translate a prescribed dose into a measurable syringe draw. That’s the beginning of responsible use, not the whole picture.
Common Questions
Does FormBlends work if you have a U-40 syringe instead of a U-100?
Yes. FormBlends explicitly supports U-100, U-50, and U-40 syringes, which is uncommon among free web tools. You select the syringe type before calculating, and the unit draw output adjusts accordingly. Most other tools on this list assume U-100 by default, so switching syringe types without adjusting your math is a real source of error elsewhere.
Can PeptideFox handle semaglutide and tirzepatide, or is it only healing peptides?
PeptideFox covers more than 30 compounds but its documented strength is traditional research peptides. For GLP-1 class compounds like semaglutide and tirzepatide specifically, MyPeptideMatch is the better fit on this list, since it was built with those dose-escalation structures in mind.
If I change how much BAC water I add to my vial, do I need to recalculate everything?
Every time. The reconstitution volume directly determines your concentration, which changes every draw amount. PeptideFox’s BAC water optimization feature is useful here because it helps you pick a water volume upfront that keeps your unit draws at clean, round numbers, reducing the chance of a measurement mistake later.
Is the FormBlends app worth using over the web calculator, or are they the same thing?
The web calculator and the app share the same core math. The app adds things the web page does not: dose logging, injection-site rotation tracking, and a 55-compound reference library. For a single calculation, the web version is fine. For anyone running a multi-peptide protocol over weeks, the app’s logging features are where the difference shows up.
Why does peptidereconstitutecalculator.com only cover BPC-157 when other tools handle dozens of compounds?
Narrow focus is the point. BPC-157 is one of the most commonly self-administered peptides, and the single-compound approach means the page loads fast and has no extra inputs to confuse a first-time user. If your only compound is BPC-157, that specificity is an advantage. For anything else on this list, you need a different tool.
Sources
- peptides.org dosage reference charts (public, independently maintained)
- peptidefox.com tool documentation
- U-100 insulin syringe standard (100 units per 1 mL), USP/FDA labeling convention
- FormBlends mobile app (iOS/Android, Expo framework, publicly listed)
- LeadWest Medical peptide calculator (public web tool)
- Outliyr peptide calculator (public web tool)
- peptidereconstitutecalculator.com (public web tool)
- MyPeptideMatch (public web tool)
- PeptideDeck (public web tool)
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