The single thing that matters most here is unit conversion accuracy. Get the mg-to-mcg math wrong by a factor of 1,000 and you draw a dose ten times too large or too small. These tools exist to close that gap.
Quick Comparison
| Tool | Syringe Types | Peptide Presets | Shows Math | App Available | Sign-up Required |
| FormBlends Peptide Calculator | U-100, U-50, U-40 | Yes (BPC-157, TB-500, ipamorelin, more) | Yes | Yes (iOS/Android) | No |
| PeptideFox | U-100 | 30+ peptides | Partial | No | No |
| MyPeptideMatch | U-100 | BPC-157, semaglutide, tirzepatide, TB-500 | No | No | No |
| LeadWest Medical | U-100 | Retatrutide, BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, sermorelin, GHK-Cu | No | No | No |
| Outliyr | U-100 | BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, GHK-Cu, GLP-1 class | No | No | No |
| PeptideDeck | U-100 | Any (manual entry) | Partial | No | No |
| peptidereconstitutecalculator.com | U-100 | BPC-157 only | No | No | No |
| peptides.org charts | Reference only | Multiple | N/A | No | No |
The Picks
1. FormBlends Peptide Calculator
The clearest thinking in this category. Before you even touch a syringe, the tool asks three things: how many milligrams came in the vial, how much bacteriostatic water you added, and what dose your provider told you to inject. From those three numbers it produces the concentration per mL, the exact units to pull into a syringe, and a running count of remaining doses.
What separates it from the anonymous pages below is transparency. The arithmetic is displayed in full so you can check it yourself, not just accept the output. That matters. A miscalculation at the measurement step is the kind of mistake nobody notices until something goes wrong.
It handles U-100, U-50, and U-40 syringes, which is unusual. Most tools assume U-100 only. A visual fill-bar shows where on the barrel your draw falls, which is genuinely useful for anyone new to insulin syringes. Presets cover the most common peptides in circulation today, BPC-157 in both 5 mg and 10 mg vials, TB-500, ipamorelin, tesamorelin, and a 50 mg GLP-1 option.
The tool also explains something most calculators ignore entirely: adding more BAC water to a vial does not change the total peptide inside it. It only changes how many units you draw per dose. That explanation alone prevents a common and costly misunderstanding.
It is built by a real company running a licensed 503A pharmacy. That does not make it infallible, but it does mean someone with regulatory accountability put their name on it. Free, no account needed, and available inside a full iOS/Android app that adds dose logging, an injection-site rotation map, and a 55-compound reference library.
2. PeptideFox
Covers more than 30 named peptides, which is the widest roster on this list. The BAC water optimization feature is a nice touch: it suggests a water volume that keeps your draw in a clean, easy-to-read range on a standard U-100 syringe. Comes with a visual reference guide. Anonymous project with no company behind it, but the functionality is real.
3. MyPeptideMatch
Free and straightforward. Notable for including semaglutide and tirzepatide alongside the classic healing peptides, so it is one of the few options that spans both GLP-1 injectables and research-oriented compounds on the same page. No math shown, no extra features. Works fine for a quick calculation.
4. LeadWest Medical
Covers a thoughtful list: retatrutide, BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, sermorelin, and GHK-Cu. Retatrutide appearing here is notable since most calculators have not caught up to newer GLP-1/GIP/glucagon tri-agonists yet. A medical clinic operates this one, which at least implies some professional review of the output.
5. Outliyr
Overlaps with LeadWest on most peptides but adds a GLP-1 class category. The site leans toward biohacking content more broadly, and the calculator reads as a companion resource rather than a standalone tool. Adequate for the peptides it lists. No login, no cost.
6. PeptideDeck
Fully manual entry. You type in the mg amount, the BAC water volume, and your target dose in mcg, and it returns concentration plus draw volume in units. No presets, no explanations. That simplicity is actually useful if you are working with a less common compound not on any preset list. The reconstitution math is the same for every lyophilized peptide regardless of what is inside the vial, so a clean general-purpose calculator like this has real utility.
7. peptidereconstitutecalculator.com
Single-purpose. BPC-157 only, mcg to units, U-100 assumed. The scope is narrow by design. If BPC-157 is the only thing you are calculating and you want the simplest possible page with no distractions, it does that job. Not useful for anything else.
8. peptides.org Dosage Charts
Not a calculator at all. Static reference charts rather than an interactive tool. Useful as a second-opinion source when cross-checking common dose ranges, but you will still need one of the tools above to convert a dose into syringe units. Worth having open in a second tab.
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One Number to Keep in Mind
1 mg equals 1,000 mcg. Full stop. Every calculator on this list exists partly because that single conversion trips people up. A U-100 insulin syringe holds 100 units across 1 mL, so 10 units is 0.1 mL. Know those two facts and the outputs from any of these tools start to make intuitive sense.
Common Questions
Which calculator is the only one that works for U-50 and U-40 syringes, not just U-100?
FormBlends is the only tool on this list that handles all three syringe types. Every other calculator assumes U-100. If your provider prescribed a U-50 or U-40 syringe for any reason, using a U-100-only calculator will produce the wrong draw volume and that is a meaningful dosing error, not a rounding issue.
Does adding more bacteriostatic water to a vial give you a weaker peptide, or does the total amount stay the same?
The total peptide stays the same. Adding more BAC water only changes the concentration, meaning you draw more units per dose to get the same amount of peptide. FormBlends explicitly explains this in its interface. Most other calculators on this list do not address it at all, which leaves a common misunderstanding unresolved.
If I am calculating for retatrutide, which tools actually have a preset for it?
LeadWest Medical is the only calculator on this list with a retatrutide preset. Retatrutide is a newer tri-agonist compound and most tools have not added it yet. If your tool of choice does not list it, PeptideDeck’s manual entry mode works for any lyophilized compound since the reconstitution math does not change by peptide name.
Is there any calculator here that also logs doses over time rather than just doing a one-time conversion?
Yes. FormBlends includes dose logging inside its iOS and Android app, along with an injection-site rotation map. None of the other tools on this list offer logging. Everything else is a one-time calculation with no record kept after you close the browser tab.
PeptideFox lists over 30 peptides but has no named company behind it. Does that make the math less trustworthy?
The math itself is the same formula regardless of who runs the site: (dose in mcg / vial size in mcg) multiplied by BAC water volume gives you the draw in mL, then converted to units. You can verify any output by hand. Anonymous authorship is worth knowing, but it does not automatically make the arithmetic wrong. Cross-checking with a second tool is a reasonable habit with any calculator.
Sources
- U-100 insulin syringe specifications: standard pharmaceutical labeling and FDA device definitions
- PeptideFox feature descriptions: peptidefox.com (public, observed 2025)
- LeadWest Medical calculator peptide list: LeadWest Medical public website
- Outliyr peptide calculator: Outliyr.com public tool
- PeptideDeck calculator: PeptideDeck.com public tool
- peptidereconstitutecalculator.com: public tool, observed 2025
- peptides.org dosage reference charts: peptides.org public pages
- FormBlends Peptide Calculator features: FormBlends public web tool and app store listing (iOS/Android)
