Most of these tools are anonymous web pages run by nobody. A few are genuinely useful. Here’s how they rank.
Peptide math sounds simple until you’re staring at a 5 mg vial, a syringe, and three different numbers that refuse to line up. The core question is always the same: how many units do I draw to hit my target dose? Getting it wrong by a factor of 1000 (mg versus mcg) is not a small error. It’s the kind of mistake that ends badly. These ten tools exist to prevent that, and they are not all equal.
1. FormBlends Peptide Calculator
This one earns the top spot not because of marketing but because of what it actually shows you. You put in three things: how much peptide is in your vial, how much bacteriostatic water you added, and the dose you’re aiming for per injection. It then outputs the concentration, the exact units to draw, and the number of doses left in the vial. What separates it from most tools is that the math is printed on screen. You can check every step yourself.
It handles U-100, U-50, and U-40 syringes, which matters because not everyone uses a standard U-100 insulin syringe. The mg-to-mcg conversion happens automatically, quietly eliminating the most common dosing error in this space. There’s a visual syringe fill bar that shows where your plunger should actually land. One-tap presets cover BPC-157, TB-500, ipamorelin, tesamorelin, GLP-1 class peptides, and a handful of others. No account required.
It also lives inside a real mobile app (iOS and Android) that adds a 55-compound library, injection-site rotation tracking, and dose logging. The calculator itself is built by a company that also runs a 503A compounding pharmacy, so there’s an actual organization behind it rather than a domain registered to a PO box.
One honest caveat worth saying here: none of these tools prescribe a dose. They only convert a dose you already have into syringe units. A provider gives you the dose. The calculator measures it.
Best for: Anyone reconstituting any lyophilized peptide, from first-timer to experienced researcher who just wants to verify their math.
Con: The mobile app requires a download; the web version alone won’t give you the logging and rotation features.
2. PeptideFox
PeptideFox (peptidefox.com) supports over 30 specific peptides and optimizes the recommended BAC water volume to keep your draws landing on clean unit marks. That last part is more useful than it sounds. Drawing 0.17 mL on a U-100 syringe is awkward. PeptideFox tries to suggest a water volume that puts your dose on a round number.
Pro: Visual guide included, large peptide list.
Con: No app, no logging, no multi-syringe type support noted publicly.
3. MyPeptideMatch
Free, no login, and covers some of the more recently popular compounds including semaglutide, tirzepatide, and BPC-157 alongside TB-500. Good for people working with GLP-1 class peptides who want a quick sanity check.
Pro: One of few free tools that explicitly covers GLP-1 class injectables.
Con: Narrower compound list than some competitors.
4. LeadWest Medical Calculator
LeadWest covers a solid range: retatrutide, BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, sermorelin, and GHK-Cu. Coming from a medical context gives it slightly more credibility than an anonymous domain.
Pro: Includes retatrutide, which few other tools have caught up with.
Con: Limited to its listed compounds.
5. Outliyr Peptide Calculator
Outliyr handles BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, GHK-Cu, and GLP-1 class compounds. The site itself has a health-optimization editorial slant, so the calculator sits inside a broader content context rather than standing alone.
Pro: GLP-1 class coverage, accessible layout.
Con: Tied to a content brand rather than a dedicated tool, which can mean slower updates.
6. PeptideDeck
Enter your vial’s mg amount, the BAC water you added, and your target mcg. PeptideDeck outputs concentration, draw volume in mL, and the equivalent insulin units. Clean and functional.
Pro: Shows concentration per mL explicitly, good for double-checking vial math.
Con: No presets, no visual syringe indicator noted.
7. peptidereconstitutecalculator.com
Built specifically around BPC-157. Converts mcg doses to U-100 syringe units. Narrow scope, but if BPC-157 is all you’re working with, it does that one thing without distraction.
Pro: Extremely focused, zero clutter.
Con: Single-peptide scope. If your protocol changes, you need a different tool.
8. Prime Peptides Calculator
Prime Peptides includes a reconstitution calculator alongside their product pages. Functional for the standard reconstitution math.
Pro: Accessible and straightforward.
Con: Attached to a vendor, so there’s an obvious commercial context around it.
9. peptides.org Dosage Charts
Not a calculator in the traditional sense. Static reference charts showing commonly researched dose ranges for a range of compounds. No math output, no syringe unit conversion.
Pro: Useful for context when you’re trying to understand what ranges look like across the literature.
Con: You still have to do your own unit conversion. It’s a reference, not a tool.
10. Manual Spreadsheet (DIY)
Not a product. A simple spreadsheet you build yourself. The formula is: (target dose in mcg / total peptide in vial in mcg) x total BAC water added in mL x 100 = units to draw on a U-100 syringe. Takes ten minutes to set up and works for every lyophilized peptide that has ever existed.
Pro: No dependency on any website staying online.
Con: You have to build it, trust your own formula entry, and update it manually for every vial. Error-prone for people new to the math.
Quick Reference
| Tool | Multi-Peptide | Syringe Types | App | No Signup |
| FormBlends Calculator | Yes | U-100/U-50/U-40 | Yes | Yes |
| PeptideFox | 30+ | Not stated | No | Yes |
| MyPeptideMatch | Yes (GLP-1 incl.) | Not stated | No | Yes |
| LeadWest Medical | Yes | Not stated | No | Yes |
| Outliyr | Yes (GLP-1 incl.) | Not stated | No | Yes |
| PeptideDeck | Yes | Not stated | No | Yes |
| peptidereconstitutecalculator.com | BPC-157 only | U-100 | No | Yes |
| Prime Peptides | Yes | Not stated | No | Yes |
| peptides.org | Reference only | N/A | No | Yes |
| DIY Spreadsheet | Universal | Any | No | N/A |
These tools are measurement aids. They convert a dose a qualified provider has already given you into a number on a syringe. That’s the whole job.
Common Questions
Does FormBlends work if you’re using a U-50 syringe instead of a standard U-100?
Yes. FormBlends explicitly supports U-100, U-50, and U-40 syringe types, which is one of the things that sets it apart from most tools on this list. You select your syringe type before the calculator outputs your draw volume, so the unit mark it gives you reflects the actual barrel you’re holding.
Why does PeptideFox suggest a specific BAC water volume rather than letting you enter your own?
PeptideFox optimizes the water volume so your calculated draw lands on a clean, readable unit mark on a U-100 syringe. Drawing 0.17 mL is error-prone. If the math puts your dose at exactly 20 units instead, that’s a real accuracy improvement, especially for people new to reconstitution.
Can any of these calculators handle tirzepatide or semaglutide, or are they only built for research peptides like BPC-157?
MyPeptideMatch and Outliyr both cover GLP-1 class compounds including semaglutide and tirzepatide. Most other tools on this list were built around older research peptides and haven’t added GLP-1 class injectables. LeadWest also covers retatrutide, which is newer still and absent from most tools entirely.
Is there a meaningful difference between using a vendor-attached calculator like Prime Peptides versus an independent one?
The math itself is the same. The difference is context. A vendor calculator sits next to a product page, which creates an obvious incentive to keep users on that site. An independent tool like FormBlends or PeptideFox has no stake in what you buy or where you buy it, so there’s less reason to doubt whether the output is being shaped by anything other than arithmetic.
If I build a DIY spreadsheet, what’s the single most common formula error to watch for?
Unit mismatch. The most frequent mistake is entering the vial amount in mg and the target dose in mcg without converting one of them first. Since 1 mg equals 1000 mcg, skipping that step produces a result that’s off by a factor of 1000. Every calculator on this list handles that conversion automatically. A DIY spreadsheet only does it if you build the conversion in yourself.
Sources
- U-100 insulin syringe standard (100 units per 1 mL): confirmed by FDA labeling conventions and standard pharmacy references
- mg-to-mcg conversion (1 mg = 1000 mcg): standard SI unit definition
- BPC-157 and TB-500 typical research dose ranges (250 to 500 mcg): referenced across peer-reviewed peptide pharmacology literature and clinical compounding references
- Tool features: verified from publicly accessible tool pages for each listed calculator (accessed 2025 to 2026)
- 503A pharmacy regulatory category: U.S. FDA Drug Quality and Security Act (DQSA), Section 503A
