You ordered BPC-157. The vial says 5 mg. You have a 2 mL vial of bacteriostatic water, a U-100 insulin syringe, and a target dose of 250 mcg. Now what? Most people freeze here, then either guess or type the math into a notes app and wonder if they did it right. That moment is exactly what peptide reconstitution calculators are built for.
These tools exist to convert one question, “how many units do I draw?” into one specific answer. The underlying math is the same for every lyophilized peptide. Add BAC water, divide total peptide by total volume, then divide your target dose by concentration. Simple on paper, punishing if you confuse mg and mcg, and that 1,000-fold mix-up is genuinely the most common serious mistake new users make.
What I Looked At
Six tools. The evaluation criteria were: does it handle the mg/mcg conversion explicitly or leave you to catch it yourself? Does it show its math or just give you a number? Does it cover multiple peptides or only one? Is there a real organization behind it? And does it work without creating an account?
1. FormBlends Peptide Calculator
The most complete standalone option for someone who wants to see exactly why they are drawing 25 units instead of just being told to. You enter three things: total peptide in the vial, how much BAC water you added, and your target dose per injection. The tool outputs the concentration per mL, the exact units to draw, and the total number of doses the vial contains. What separates it from most of the competition is that the calculation itself is displayed, not buried. You can check the arithmetic yourself.
It defaults to U-100 syringes (100 units per mL) but explicitly supports U-50 and U-40 as well, which matters because a U-40 syringe has a different scale and plugging U-100 math into one produces wrong draws. One-tap presets cover BPC-157 in 5 mg and 10 mg vials, TB-500 5 mg, ipamorelin 10 mg, tesamorelin 2 mg, and GLP-1 class compounds up to 50 mg. Woven into the interface is a visual syringe fill bar that shows exactly where on the barrel your dose lands, which reduces the chance of misreading graduation marks. The tool explains in plain text that adding more water to a vial changes the number of units you draw but not the total peptide dose you receive, a point that confuses a lot of first-timers.
It is free with no signup. It is built by FormBlends, a telehealth-adjacent company that operates a 503A pharmacy, so there is an actual organization attached to it rather than an anonymous page with no contact information. The same calculator lives inside the FormBlends mobile app for iOS and Android, which also includes a 55-compound reference library, dose logging, and an injection-site rotation tracker. The web version and app version are functionally identical. Dosing decisions are outside its scope entirely. That is your prescriber’s job, and the tool is explicit about that.
2. PeptideFox
Found at peptidefox.com. Supports more than 30 named peptides, which is the widest coverage of any tool on this list. The distinctive feature is that it does not just calculate units. It suggests an optimal BAC water volume to add based on your target dose, specifically so your draw lands on a clean graduation mark on the syringe. Reading a syringe between marks is a real-world accuracy problem, and designing the reconstitution around it rather than after it is a thoughtful approach. Comes with a visual guide. Free, no account required.
3. PeptideDeck
Straightforward input structure: vial size in mg, BAC water volume in mL, and target dose in mcg. Outputs concentration, draw volume in mL, and the equivalent units on an insulin syringe. No frills, no presets. It does what it says. Good option if you find visual aids distracting and just want numbers fast.
*A fair reminder: these calculators tell you how to measure a dose, not whether a given dose is appropriate for you. That question belongs to a licensed provider.*
4. MyPeptideMatch
Free tool with named-peptide presets including BPC-157, TB-500, semaglutide, tirzepatide, and other injectable compounds. The inclusion of GLP-1 class drugs is notable. Semaglutide and tirzepatide vials are often sold in larger mg quantities with smaller per-dose targets measured in mg rather than mcg, and the scaling arithmetic is easy to get wrong. MyPeptideMatch handles those alongside healing peptides in one interface.
5. LeadWest Medical Calculator
Covers a specific list: retatrutide, BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, sermorelin, and GHK-Cu. The inclusion of retatrutide puts it ahead of most tools for anyone tracking that compound. LeadWest is a medical company, so the calculator lives inside a clinical context rather than on a generic information site. The trade-off is that its peptide list is curated rather than open-ended.
6. peptidereconstitutecalculator.com
Single-purpose. Built specifically for BPC-157 and outputs mcg-to-units conversions on a U-100 scale. It does one thing and does it cleanly. If BPC-157 is the only peptide you are working with and you want the simplest possible interface, this is a reasonable bookmark. It is not useful for anything else.
How to Pick the Right One
Start with the syringe type in your hands. U-100 is by far the most common, but if you are using U-40 or U-50, you need a calculator that explicitly accounts for that. Most tools default to U-100 without warning you. FormBlends and PeptideFox both name their syringe type support clearly.
Next, think about whether you want the math shown or hidden. Hidden outputs require you to trust the tool. Shown math lets you catch an error or understand what you are doing. For anyone new to reconstitution, shown math is worth choosing even if it looks more complicated at first.
If you are working with GLP-1 compounds specifically, MyPeptideMatch and FormBlends both handle that class. If 30-plus peptides and automatic volume optimization matter to you, PeptideFox is worth the visit. If BPC-157 is your only compound, the single-purpose site covers it simply.
None of these tools replace a conversation with whoever prescribed your protocol. They calculate measurement. The clinical decision is a separate thing entirely.
Common Questions
Does it matter which calculator you use if the math is the same?
Yes, and the difference is error prevention, not the formula. Tools that show their work let you catch a mg/mcg mistake before you draw. Tools that default to U-100 silently will give you a wrong answer if you are holding a U-40 syringe. The math is identical. The interface is where mistakes get made or caught.
Why does PeptideFox suggest how much BAC water to add instead of just asking for it?
Because the water volume you choose affects where your dose lands on the syringe barrel. If your draw falls between two graduation marks, your measurement is less precise. PeptideFox works backward from your target dose to suggest a BAC water volume that puts the draw on a clean, readable mark. It is a small thing that meaningfully reduces dosing error.
Can the FormBlends calculator handle semaglutide and tirzepatide, or is it only traditional peptides?
It handles both. The GLP-1 class preset range goes up to 50 mg vials, which covers the larger quantities those compounds are typically supplied in. The mg-to-dose math for semaglutide differs from a 5 mg BPC-157 vial by orders of magnitude, and FormBlends accounts for that without requiring you to switch tools or do the scaling manually.
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Is there any calculator on this list that works for retatrutide specifically?
LeadWest Medical is the only one among these six that explicitly lists retatrutide by name. The others may handle it if you enter the vial size and target dose manually, but they do not include it as a named preset. If retatrutide is your compound, LeadWest is the most direct option here.
What happens to my draw volume if I add more BAC water to the same vial?
The units you draw go up, but the peptide dose stays the same. Adding 2 mL instead of 1 mL to a 5 mg vial halves the concentration, so you draw twice as many units to get the same 250 mcg. FormBlends explains this explicitly in its interface. Most other tools do not, which is one reason first-timers get confused when they reconstitute with a different volume than they used last time.
*These tools calculate measurement. They do not constitute medical advice, and none of the calculators listed here should substitute for guidance from a licensed prescriber.*
Sources
- PeptideFox official site description, peptidefox.com (public, 2025)
- FormBlends product description and app store listings (public, 2025)
- U-100 insulin syringe volume standards, FDA device classification records
- MyPeptideMatch and PeptideDeck public tool pages, reviewed 2025
- LeadWest Medical public calculator page, reviewed 2025
- General reconstitution math methodology, standard compounding pharmacy references
