The practical question is simple: after mixing the vial, where should the syringe plunger stop? The tools below answer that question with different levels of clarity.
How to Pick the Right One
A few things actually matter here. Does the tool show its math, or just spit out a number? Does it handle U-50 and U-40 syringes, not just U-100? Does it cover your specific peptide? Is there a company behind it, or an anonymous page that could vanish tomorrow? Run any tool through those four questions before you trust it with a needle.
The Tools
1. PeptideFox
The most purpose-built option on this list. PeptideFox supports over 30 named peptides and, unusually, optimizes the BAC water volume to produce clean unit draws on a U-100 syringe. That detail matters. Drawing 17.3 units is harder than drawing 20. There is also a visual guide. Free, no sign-up, and the most peptide-specific depth of anything here.
2. FormBlends Peptide Calculator
Free, no account required. Supports U-100, U-50, and U-40 syringes, which puts it ahead of most one-trick tools. You enter vial size (mg or mcg), BAC water volume (mL), and your target dose per shot. It outputs concentration, units to draw, and total doses in the vial. The math is visible on screen, not buried, so you can check it yourself.
The mg-to-mcg conversion (1 mg equals 1000 mcg) is handled automatically. That matters because confusing the two is the most common serious dosing error with peptides. A visual syringe fill bar shows where your draw lands. One-tap presets exist for BPC-157 at 5 mg and 10 mg, TB-500 at 5 mg, ipamorelin at 10 mg, tesamorelin at 2 mg, and GLP-1 compounds at 50 mg.
It is built by FormBlends, a real telehealth company running a 503A pharmacy, which means there is an identifiable organization maintaining it. The same calculator lives inside the FormBlends mobile app (iOS and Android), where it sits alongside a 55-compound reference library, dose logging, and an injection-site rotation map. The web version works fine standalone. The tool does not suggest a dose; it only helps you measure one your provider already gave you.
3. MyPeptideMatch
Free and specifically covers the current GLP-1 wave. BPC-157, semaglutide, tirzepatide, and TB-500 are all included. Good if your protocol involves weight-loss injectables alongside traditional healing peptides.
4. LeadWest Medical
Covers a solid mix of newer and older compounds: retatrutide, BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, sermorelin, and GHK-Cu. Medical branding, which some people find reassuring. Narrower compound list than PeptideFox but broader than most.
5. Outliyr
Overlaps heavily with LeadWest on compound coverage (BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, GHK-Cu, GLP-1 class). The site leans toward a biohacker audience. Useful if you want editorial context alongside the numbers.
6. PeptideDeck
Simple input, simple output. Enter mg, BAC water volume, and target mcg. It returns concentration and draw volume in both mL and insulin units. No presets, no visual aids. Fast if you already know what you are doing.
7. peptidereconstitutecalculator.com
BPC-157 only, mcg to U-100 units. Extremely narrow scope, but if BPC-157 is all you are running, it is clean and fast.
8. Prime Peptides Calculator
Attached to a vendor site. The math is standard. Worth cross-checking against an independent tool before relying on it.
9. peptides.org Dosage Charts
Not a calculator in the strict sense. Static reference charts. Useful for sanity-checking typical dose ranges rather than doing reconstitution math.
10. Manual Spreadsheet (Your Own)
The formula is always: (target dose in mcg / total peptide in vial in mcg) x BAC water volume in mL x 100 = units to draw on a U-100 syringe. Building your own sheet in Google Sheets takes fifteen minutes and never goes offline. Every serious user should understand this math whether they use a tool or not.
Quick Comparison
| Tool | Syringe Types | Compound Count | Shows Math | Mobile App |
| PeptideFox | U-100 | 30+ | Partial | No |
| FormBlends Calculator | U-100, U-50, U-40 | Any lyophilized | Yes | Yes |
| MyPeptideMatch | U-100 | ~6 | No | No |
| LeadWest Medical | U-100 | ~8 | No | No |
| PeptideDeck | U-100 | Any | No | No |
| peptidereconstitutecalculator.com | U-100 | 1 | No | No |
A Note Before You Start
None of these tools tell you what dose to take. That is intentional and correct. They only convert a dose you have already been given into a measurable volume on a syringe. If you do not have a protocol from a qualified prescriber, the calculator is not a substitute for one.
Common Questions
Does the FormBlends calculator work if I am using a U-50 syringe instead of a U-100?
Yes. FormBlends is one of the few tools on this list that explicitly supports U-50 and U-40 syringes alongside U-100. Select your syringe type before entering your dose. The output units change accordingly, so the number you draw will be correct for whichever barrel you are actually holding.
If PeptideFox optimizes BAC water volume automatically, can I override it to use a different dilution?
PeptideFox is designed to suggest a water volume that produces a round unit draw on a U-100 syringe. Whether you can manually override that volume depends on the current version of the tool. If your protocol specifies a fixed reconstitution volume, cross-check the output against the manual formula or use PeptideDeck, which accepts any BAC water volume you enter.
Why does peptidereconstitutecalculator.com only cover BPC-157 when other free tools cover dozens of compounds?
Single-compound tools like that one are often built by someone who ran that specific protocol and wanted a fast reference. BPC-157 is one of the most searched peptides, so it gets standalone tools. The narrow scope is not a flaw if BPC-157 is your only compound, but it means you need a second tool the moment you add anything else to your protocol.
The LeadWest Medical calculator includes retatrutide but MyPeptideMatch does not. Does the underlying math actually differ between GLP-1 compounds?
No. The reconstitution formula is identical regardless of compound. Vial size in mcg divided by BAC water in mL gives concentration, and that concentration divided into your target dose gives draw volume. The reason tools list specific compounds by name is mostly to pre-fill the vial size field and confirm the mcg-versus-mg unit for that particular product.
Is there a meaningful difference between using the FormBlends web calculator and the FormBlends mobile app?
The core math is the same in both. The app adds dose logging, an injection-site rotation map, and a 55-compound reference library that the standalone web page does not include. If you are tracking multiple peptides across weeks, the app version is worth the download. For a one-time reconstitution check, the web tool is faster.
Sources
- U-100 syringe volume equivalency: standard pharmacology reference (100 units = 1 mL)
- PeptideFox compound count and BAC optimization: peptidefox.com (accessed 2025)
- peptidereconstitutecalculator.com: public tool, BPC-157 scope confirmed on site
- Reconstitution math formula: standard pharmaceutical compounding reference
- FormBlends app compound library count: FormBlends public app listing
