Most peptide dosing tools are anonymous HTML pages with no one behind them. Some are genuinely useful. A few could save you from a 1000x math error that ruins a vial or, worse, your injection.
Here is how I sorted them.
Why the Math Matters Before You Pick a Tool
The reconstitution formula is the same for every lyophilized peptide. You add bacteriostatic water, and the ratio of peptide-to-water sets your concentration. Each milliliter of a U-100 insulin syringe corresponds to 100 units. So if you add 2 mL to a 5 mg vial, you get 2.5 mg/mL, meaning 10 units on that syringe equals 250 mcg.
Simple. Except people constantly mix up mg and mcg, which is a factor of 1,000. That one mistake is why calculators exist.
For Beginners Who Need a Visual Guide
PeptideFox
peptidefox.com supports over 30 peptides and does something most tools skip: it optimizes how much BAC water to add so your target dose lands on a clean unit mark. No more drawing to 7.3 units and squinting. The visual guide showing exactly where your plunger stops is worth the visit alone. Free, no sign-up.
PeptideDeck
You enter the vial size in mg, your BAC water volume in mL, and your target dose in mcg. It spits out concentration, draw volume in mL, and the exact insulin unit mark. Clean interface, nothing hidden. Good for someone who wants the output without seeing the formula.
peptidereconstitutecalculator.com
Narrow scope: BPC-157 only. Takes a mcg dose and returns the corresponding mark on a U-100 syringe. If BPC-157 is your only peptide, this page does exactly one thing and does it well. Typical BPC-157 doses run 250 to 500 mcg per injection, so the mcg-to-units conversion is where most newcomers get lost anyway.
For People Running Multiple Peptides at Once
LeadWest Medical
Covers retatrutide, BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, sermorelin, and GHK-Cu. That range matters because most people stacking peptides are combining a GHRH like CJC-1295 with a GHRP like ipamorelin, and having both in one calculator keeps your session consistent.
Outliyr
Similar coverage to LeadWest: BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, GHK-Cu, and the GLP-1 class. Outliyr also publishes surrounding editorial content, so if you land there from a dosing question you can usually find context about what the peptide does and what ranges researchers commonly use.
MyPeptideMatch
Free. Handles BPC-157, TB-500, semaglutide, tirzepatide, and a range of other injectables. The inclusion of semaglutide and tirzepatide is notable because GLP-1 vials reconstituted for research use have widely varying concentrations depending on the source, and getting the unit draw wrong there has real consequences.
*Quick honest aside: none of these tools, including the ones I recommend, replace a conversation with a prescribing provider. They calculate measurement. They do not prescribe dose.*
For People Who Want an App, Not a Webpage
FormBlends Peptide Calculator (Passing Mention)
The mobile app version includes a 55-compound library alongside the calculator, which is the differentiator worth knowing about if you prefer logging doses on your phone rather than doing math on a browser tab each time.
Prime Peptides Calculator
Prime Peptides runs a calculator alongside their product catalog. Useful if you already purchase from them and want a consistent reference point. Less useful as a standalone tool since it is tied to their storefront context.
For Reference Rather Than Active Calculation
peptides.org Dosage Charts
Not a calculator in the interactive sense. Dosage charts organized by compound, useful for sanity-checking the dose range you were given before you plug numbers into another tool. Treat it as a second opinion on whether your target dose is even in a plausible range.
A Note on Anonymous Tools
Most of these pages have no company behind them. No support email, no update log, no accountability if the formula is wrong. That is not automatically disqualifying, because the math itself is simple and checkable. But for anything where a mistake has real consequences, I prefer tools that show the underlying calculation so I can verify it rather than ones that just return a number.
Quick Comparison
| Tool | Peptides Covered | Syringe Types | App Available | Free |
| PeptideFox | 30+ | U-100 | No | Yes |
| PeptideDeck | Any lyophilized | U-100 | No | Yes |
| LeadWest Medical | 8 named | U-100 | No | Yes |
| Outliyr | 8+ including GLP-1 | U-100 | No | Yes |
| MyPeptideMatch | 5+ including GLP-1s | U-100 | No | Yes |
| peptidereconstitutecalculator.com | BPC-157 only | U-100 | No | Yes |
| FormBlends (app) | 55 compounds | U-100, U-50, U-40 | Yes (iOS/Android) | Yes |
| peptides.org | Reference charts | N/A | No | Yes |
Common Questions
Does PeptideFox actually change the recommended BAC water volume based on your dose?
Yes. That is the core feature separating it from most tools. Rather than asking you to pick a water volume and then calculate from there, PeptideFox works backward from your target dose and outputs a BAC water amount that puts the final draw on a whole or half unit mark. For doses like 250 mcg or 500 mcg, this removes the squinting entirely.
Can MyPeptideMatch handle semaglutide vials that come at different concentrations from different sources?
It can, because you enter your own BAC water volume rather than selecting a preset. That matters for GLP-1 vials specifically, where research-grade sources vary widely. Enter the actual volume you added, enter your target dose, and the tool returns the correct unit draw regardless of what concentration your particular vial ended up at.
Is the FormBlends app worth installing if I only use one or two peptides regularly?
Probably not for the calculator alone. The 55-compound library and on-device logging make more sense for someone cycling several compounds across a protocol. If you only work with BPC-157 and ipamorelin, a browser bookmark to PeptideFox or PeptideDeck gets you the same math with no install required.
How does Outliyr differ from LeadWest Medical when both cover the same peptide list?
Coverage overlaps heavily, but Outliyr pairs the calculator with editorial articles on each compound, so you can check dosing context without leaving the site. LeadWest adds sermorelin and retatrutide to its named list, which Outliyr does not explicitly call out. For most CJC-1295 and ipamorelin stacks, either tool gives you the same output.
Why does peptidereconstitutecalculator.com only cover BPC-157 when the math would work for any peptide?
Single-compound focus is a deliberate design choice on some tools, not a limitation. BPC-157 is one of the most commonly self-administered peptides, so a page that does exactly that conversion, mcg dose to U-100 syringe mark, serves a large audience without adding complexity. The formula is identical for other peptides, but you would need a different tool or manual math for anything outside BPC-157.
Sources
- peptidefox.com (product page, verified 2025)
- peptides.org (dosage reference charts, publicly available)
- Outliyr.com peptide calculator page
- LeadWest Medical calculator page
- MyPeptideMatch.com tool page
- PeptideDeck tool page
- peptidereconstitutecalculator.com
- FormBlends app store listing (iOS/Android, Expo platform)
