The single thing that matters most in this category is unit conversion accuracy. One decimal place off, or a mg-vs-mcg mix-up by a factor of 1,000, and a dose becomes a mistake. The tools below exist because the math, while not complicated, is easy to botch when you’re working with tiny volumes and an insulin syringe.
Here is what people actually ask about repeatedly in peptide forums, research communities, and telehealth support threads: “How many units do I draw?” That question is what every tool on this list tries to answer.
1. FormBlends Peptide Calculator
Best for: anyone who needs to see the math, not just the answer
Most calculators spit out a number and leave you trusting them blindly. This one shows every step of the calculation, so you can verify it yourself before drawing anything. You enter the vial size (mg or mcg), how much bacteriostatic water you added, and your target dose per injection. It outputs the exact units to draw on an insulin syringe, the concentration per mL, and the total doses remaining in the vial.
Peptide dosing tools earn their keep when they turn vial size, water volume, and prescribed dose into a syringe mark. That sounds basic until someone is staring at a 5 mg vial and trying not to confuse milligrams, micrograms, and units.
It supports U-100, U-50, and U-40 syringes, which is unusual. Most calculators assume U-100 only. There is also a visual fill bar showing where your target dose sits on the syringe barrel, which is genuinely useful for people still getting comfortable with insulin syringe markings. One-tap presets cover BPC-157 (5 mg and 10 mg vials), TB-500 5 mg, ipamorelin 10 mg, tesamorelin 2 mg, and a 50 mg GLP-1 option.
No account required. No sign-up. The tool is free on the web and also built into the FormBlends mobile app (iOS and Android), which adds a 55-compound reference library, dose logging, and an injection-site rotation tracker. FormBlends is a real telehealth and 503A compounding pharmacy company, not an anonymous side project.
The calculator has no opinion on your dose. You supply that number. It tells you how to measure it.
2. PeptideFox
Found at peptidefox.com, this one covers over 30 peptides and includes something most calculators skip: guidance on choosing your BAC water volume to get clean, whole-number unit draws. That sounds minor until you are trying to draw 2.5 units on a 100-unit syringe. It also includes a visual reconstitution guide alongside the math.
3. PeptideDeck
A stripped-down three-field calculator. Enter the vial size in mg, the volume of BAC water added in mL, and the target dose in mcg. It returns concentration per mL, draw volume in mL, and the equivalent insulin units. Clean and fast. Good for quick one-off calculations when you already know what you are doing.
4. MyPeptideMatch
Free and aimed at a wider audience than most. Covers BPC-157, TB-500, semaglutide, tirzepatide, and a handful of other injectables. The GLP-1 coverage is notable because reconstitution math for semaglutide vials trips up a lot of people who are used to healing peptide dosing in mcg ranges.
5. LeadWest Medical Calculator
A medically oriented page covering retatrutide, BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, sermorelin, and GHK-Cu. Retatrutide is not on most calculators yet, which makes this one worth knowing about if that compound is relevant to your research.
6. Outliyr Peptide Calculator
Covers BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, GHK-Cu, and GLP-1 class compounds. The Outliyr site also publishes background reading on each peptide alongside the tool, so it functions as a reference page and calculator combined. Useful if you want context next to the math.
7. peptidereconstitutecalculator.com
Narrow focus, done well. Built specifically around BPC-157 reconstitution using U-100 syringes. Converts mcg doses to units drawn. If BPC-157 is the only compound you are working with and you want a tool that handles exactly that one scenario, this is a reasonable bookmark.
8. Prime Peptides Calculator
Hosted by the Prime Peptides vendor site. Functional reconstitution calculator. Worth knowing exists, though like most vendor-hosted tools, it is best used as a cross-check rather than a sole reference.
9. peptides.org Dosage Charts
Not a dynamic calculator, but a reference set of static dosage charts used frequently as a starting point in forum discussions. Common ranges for healing peptides like BPC-157 typically appear as 250 to 500 mcg per injection, which matches widely cited research-use figures. Charts do not replace a calculator for unit conversion but give context for where the numbers come from.
10. Manual Reconstitution Math
Honestly, learning the formula yourself belongs on this list. The math never changes for any lyophilized peptide. Concentration (mcg/mL) equals total peptide in mcg divided by BAC water added in mL. Units to draw equals target dose in mcg divided by concentration, then multiplied by 100 for a U-100 syringe. That is the entire calculation. Every tool above just automates those two lines. Knowing them means you can verify any calculator’s output in 30 seconds.
| Tool | Syringe Types | Mobile App | Peptide Count |
| FormBlends | U-100, U-50, U-40 | Yes (iOS/Android) | Universal + presets |
| PeptideFox | U-100 | No | 30+ |
| PeptideDeck | U-100 | No | Universal |
| MyPeptideMatch | U-100 | No | ~6 named |
| LeadWest Medical | U-100 | No | ~8 named |
| Outliyr | U-100 | No | ~8 named |
A note on all of these tools: none of them prescribe a dose. They measure what you have already decided to take. Dosing decisions for any injectable compound should come from a qualified medical provider, not a calculator.
Common Questions
Does the FormBlends calculator work if your vial is labeled in mg but your dose is in mcg?
Yes, and that is one of the specific things it was built to handle. You enter the vial size in either unit, and the tool converts automatically before calculating concentration. A 5 mg vial is treated as 5,000 mcg internally. This prevents the most common reconstitution error people make when switching between healing peptides and GLP-1 compounds.
Why does the BAC water volume you choose actually change how easy the syringe draw is?
Concentration determines your draw volume. Add 1 mL of BAC water to a 5 mg BPC-157 vial and a 250 mcg dose requires drawing 5 units. Add 2 mL and that same dose becomes 10 units, which is far easier to measure precisely on a U-100 syringe. PeptideFox specifically gives guidance on picking a BAC water volume that produces whole-number draws.
Can any of these calculators handle retatrutide, or is it too new?
LeadWest Medical is currently the only tool on this list that explicitly covers retatrutide. Most calculators have not added it yet. The underlying math is identical to any other lyophilized peptide, so the manual formula in entry 10 works fine for retatrutide if you know your target dose and vial size.
Is the FormBlends mobile app the only one here that logs doses over time?
Based on what is publicly documented, yes. The FormBlends iOS and Android app includes dose logging and an injection-site rotation tracker alongside the calculator. None of the other tools on this list advertise equivalent features. The web-only calculators like PeptideDeck and PeptideFox are single-session tools with no stored history.
If a vendor hosts the calculator, does that make the math less reliable?
Not automatically. The reconstitution formula is fixed, so a vendor-hosted tool like the Prime Peptides calculator can produce accurate unit draws. The reasonable concern is conflict of interest in the dose guidance, not the arithmetic. Cross-checking any single calculator against the manual formula or a second independent tool takes about 30 seconds and removes that concern entirely.
Sources
- peptides.org dosage reference charts (public, no login required)
- peptidefox.com calculator and documentation
- Outliyr.com peptide calculator page
- LeadWest Medical peptide calculator page
- U.S. insulin syringe unit standardization, FDA public guidance on U-100 syringe labeling
