The single thing that matters most when choosing a peptide calculator is whether it shows you the math, not just the answer.
A black-box number you cannot verify is a liability when the difference between micrograms and milligrams is literally a 1000x error. I went through every tool I could find in 2025-2026, ran the same reconstitution scenario through each one, and ranked them below.
The Comparison Table
| Tool | Syringe Types | Shows Math | Preset Peptides | App / Logging | Sign-up Required |
| FormBlends Peptide Calculator | U-100, U-50, U-40 | Yes | BPC-157, TB-500, ipamorelin, tesamorelin, GLP-1, more | Yes (iOS/Android) | No |
| PeptideFox | U-100 | Partial | 30+ | No | No |
| PeptideDeck | U-100 | Yes | None | No | No |
| LeadWest Medical | U-100 | No | 7 named peptides | No | No |
| MyPeptideMatch | U-100 | No | BPC-157, semaglutide, tirzepatide, TB-500 | No | No |
| Outliyr | U-100 | No | BPC-157, TB-500, ipamorelin, CJC-1295, GHK-Cu, GLP-1 | No | No |
| peptidereconstitutecalculator.com | U-100 | Partial | BPC-157 only | No | No |
1. FormBlends Peptide Calculator
My top pick, and not because of aesthetics.
What pushed it to number one is the combination of transparent arithmetic and multi-syringe support sitting inside a tool built by an actual company rather than an anonymous page. When I entered a 5 mg BPC-157 vial reconstituted with 2 mL of bacteriostatic water and a 250 mcg target dose, the calculator spit out the draw volume in units, showed the concentration per mL, told me how many doses the vial holds, and displayed a visual fill bar on a syringe diagram so I could double-check against a physical syringe before drawing. It also flagged the mg-to-mcg conversion automatically, which matters because that 1 mg = 1000 mcg relationship is the exact spot where people make catastrophic errors.
What I appreciate most is that a peptide preset like the 10 mg ipamorelin option auto-fills the vial weight field, but I can override everything manually. The same calculator lives inside the FormBlends mobile app (iOS and Android, built on Expo), which adds a 55-compound reference library, injection-site rotation tracking, and a dose log. That package does not exist anywhere else in one place.
No login. No email. The math is visible and checkable.
2. PeptideFox
PeptideFox (peptidefox.com) is the strongest pure-web alternative I found.
It supports over 30 peptides by name, which is the widest selection list of any standalone page I tested. There is a visual guide that explains where on a syringe a particular draw volume falls, which is genuinely helpful for anyone new to U-100 syringes. The BAC water volume optimization feature is a nice touch. It suggests how much water to add to get clean, round unit draws rather than awkward decimals. That alone saves mental effort.
It does not, however, support U-50 or U-40 syringes. And it does not show the underlying formula. I got the right answer for my test case but could not verify why.
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3. PeptideDeck
Short, functional, no frills.
PeptideDeck asks for three inputs: milligrams of peptide, milliliters of BAC water added, and target dose in micrograms. It returns concentration, draw volume, and insulin units. It does show the math, which is why it ranks above several more feature-rich tools. Verifiable output matters more than a polished interface.
No presets. No app. No syringe type selection beyond U-100. For someone who just needs to check a single calculation quickly without any context, this works fine.
4. LeadWest Medical
LeadWest Medical’s calculator covers seven specific peptides: retatrutide, BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, and sermorelin. That list reads like a solid starter kit for the most commonly discussed research peptides in 2025.
The interface is clean and the output is clear. What it does not do is show the formula it used, so you are trusting the result rather than confirming it. It is also tied to a specific vendor’s site, which is worth keeping in mind when evaluating independence. Still, for anyone working with those seven compounds and who already understands the reconstitution math from another source, it gets the job done.
5. MyPeptideMatch
Free, no login, and one of the few tools that explicitly covers GLP-1 class compounds alongside traditional peptides.
MyPeptideMatch includes semaglutide and tirzepatide alongside BPC-157 and TB-500, which reflects where the peptide-adjacent conversation has moved over the last two years. The interface is simple. The math, though, is not surfaced. You get the answer with no formula visible, and for a GLP-1 compound where dosing steps are incremental and errors carry real consequences, I would want to cross-reference against another source.
6. Outliyr
Outliyr’s calculator is embedded in a broader health optimization content site, and it covers a solid range: BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, GHK-Cu, and GLP-1 class compounds.
The tool is functional and free. But the math is hidden, and the site context is more editorial than clinical. I would use it as a quick sanity check rather than a primary tool. The surrounding articles are generally well-sourced, which at least suggests the calculator inputs are based on reasonable assumptions.
7. peptidereconstitutecalculator.com
This one does exactly one thing: converts a BPC-157 dose in micrograms to units on a U-100 syringe.
If BPC-157 is the only thing you are working with and you already know your vial concentration, this gets you there in about ten seconds. It is BPC-157-specific, which is limiting, but it is also one of the most searched peptide reconstitution problems online. The partial math display is enough to follow the mcg-to-units logic. Worth bookmarking if BPC-157 is your only use case.
FAQ
What is the most common mistake peptide calculators prevent?
Confusing milligrams and micrograms. One milligram equals 1,000 micrograms. A dose intended as 500 mcg that gets drawn as 500 mg would be a 1,000x overdose. Good calculators either auto-convert or make the unit explicit at every step.
Does adding more bacteriostatic water change my dose?
No. Adding more water changes the concentration, which changes how many units you draw, but the total peptide in the vial does not change. A 5 mg vial reconstituted with 1 mL or 3 mL still has 5 mg in it. The calculator adjusts the draw volume accordingly.
Why do most of these tools only support U-100 syringes?
U-100 (100 units per 1 mL) is the standard insulin syringe in the United States. U-50 and U-40 syringes exist but are far less common in this context. The math changes because the unit-to-volume ratio changes, so a calculator that only assumes U-100 will give wrong draw volumes if you are using another syringe type.
Can I use any of these tools for GLP-1 peptides like semaglutide?
The underlying arithmetic works the same way across all lyophilized peptides. Some tools (MyPeptideMatch, Outliyr, FormBlends) explicitly list GLP-1 compounds as presets. Others work fine if you enter the vial weight and water volume manually.
Do these calculators tell me what dose to take?
None of the reputable ones do. You enter a dose that a qualified provider has prescribed or recommended. The calculator only tells you how to measure that dose accurately with an insulin syringe. Dosing decisions belong with a medical professional.
Sources
- U-100 syringe unit-to-volume standard: FDA guidance on insulin syringe labeling and USP syringe specifications
- BPC-157 and TB-500 common dosing ranges: published research and clinical pharmacology references cited at peptides.org
- Reconstitution math (lyophilized peptides): standard compounding pharmacy calculations, publicly documented in USP general chapters on sterile compounding
- PeptideFox feature list: peptidefox.com (publicly accessible, reviewed January 2026)
- PeptideDeck feature list: peptideckcalculator.com (publicly accessible, reviewed January 2026)
- FormBlends mobile app: App Store and Google Play listings for FormBlends (Expo-based, publicly listed)
