Peptide calculators are valuable because small unit mistakes can become large dosing mistakes. The better tools make the conversion visible instead of hiding it behind a black-box answer.
Here are 12 free calculators worth bookmarking, ranked by how useful I find them day to day.
1. FormBlends Peptide Calculator
The thing I appreciate most is that it shows the arithmetic. You can see exactly how the concentration per mL was derived from your vial size and water volume, which means you can spot a typo before you draw anything. Enter your vial’s peptide amount, how many mL of BAC water you added, and your target dose per shot. It returns concentration, units to draw, and dose count per vial. It handles the mg-to-mcg conversion automatically, which eliminates the most dangerous user error in this whole process. One-tap presets cover BPC-157 (5 mg and 10 mg vials), TB-500, ipamorelin, tesamorelin, and a GLP-1 preset at 50 mg. A visual syringe fill bar shows where your dose sits on the barrel. Unusually, it supports U-50 and U-40 syringes alongside U-100. The same math engine lives inside the FormBlends mobile app, which adds dose logging, an injection-site rotation map, and a 55-compound reference library. No account required on either version.
Best for: Anyone who wants to verify the math themselves rather than trust a black box.
2. PeptideFox
peptidefox.com covers more than 30 named peptides and does something most tools skip: it helps you pick a BAC water volume that lands your dose on a clean unit mark. No awkward 0.073 mL draws. The visual injection guide is genuinely useful for beginners.
Pro: Optimizes for clean syringe reads.
Con: Peptide list, while long, is fixed. Custom entries require workarounds.
3. PeptideDeck
You enter mg of peptide, mL of water, and target dose in mcg. It outputs concentration and draw volume in both mL and insulin units. Fast. No fluff.
Pro: Clean three-field interface, quick to use on a phone.
Con: No presets. You build every entry from scratch.
4. MyPeptideMatch
Covers BPC-157, semaglutide, tirzepatide, and TB-500, which makes it one of the few free tools that handles GLP-1 class peptides alongside the healing peptides. Free with no login.
Pro: GLP-1 and healing peptides in the same place.
Con: Peptide selection is curated, not open-ended.
5. LeadWest Medical Calculator
Lists retatrutide, BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, sermorelin, and GHK-Cu. The fact that it comes from a medical context means the framing is a bit more clinical, which some people prefer.
Pro: Covers retatrutide, which many tools ignore.
Con: Interface is basic. Not much guidance for first-timers.
6. Outliyr Peptide Tool
Handles BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, GHK-Cu, and GLP-1 class options. Outliyr wraps the calculator inside broader biohacking content, so there’s context around the numbers.
Pro: Good accompanying explanations of what each peptide is.
Con: The editorial content can distract from just getting the number you need.
7. peptidereconstitutecalculator.com
BPC-157 specific. Takes a mcg dose and translates it to the corresponding graduation on a U-100 syringe. That’s the whole tool. If BPC-157 is all you’re working with, that focus is actually a feature.
Pro: Zero learning curve.
Con: Useless for anything other than BPC-157.
8. Prime Peptides Calculator
Straightforward reconstitution tool. Works on the same universal math (which applies to any lyophilized peptide, not just the ones on a preset list).
Pro: Works for generic entries, not just named compounds.
Con: Minimal documentation. Unclear who maintains it.
9. peptides.org Dosage Charts
Static reference tables rather than an interactive tool you type numbers into. Shows typical dose ranges for common peptides.
Pro: Good for double-checking that your provider’s numbers are in a reasonable range.
Con: You still have to do the reconstitution math yourself.
10. Reddit Pinned Calculators (r/Peptides)
The community pins spreadsheet-based tools periodically. Community-vetted, frequently updated.
Pro: Peer-reviewed in a practical sense.
Con: Links change. Not guaranteed to be there next month.
11. Generic Google Sheets Templates
Several circulate in peptide communities. You copy the sheet, enter your numbers, and it runs the same formula every other tool does.
Pro: Fully auditable. You can read every cell.
Con: You have to find a trustworthy template first.
12. Manual Calculation
Concentration (mcg/mL) = total peptide mcg divided by mL of BAC water. Units to draw = (target dose in mcg / concentration) x 100. That’s it.
Pro: Works everywhere, always, with no app required.
Con: Easy to fat-finger, especially under time pressure.
One reminder worth stating: adding more BAC water to a vial changes how many units you draw per dose, but it does not change how much peptide you’re actually injecting. That trips people up constantly. All of these tools do the same underlying math. The differences are interface, transparency, and how much hand-holding they offer around that core formula.
Common Questions
Does it matter which calculator I use if the underlying formula is the same?
Mostly no, but transparency does matter. FormBlends shows its arithmetic step by step, which lets you catch a bad input before you draw. Tools that just spit out a number without showing work give you no way to sanity-check. For anything above a routine dose, pick a tool that shows the math.
Can PeptideFox or MyPeptideMatch handle a peptide that isn’t on their preset list?
PeptideFox requires workarounds for anything outside its fixed list of 30-plus named compounds. MyPeptideMatch’s selection is curated and not open-ended. If you’re working with a less common peptide, PeptideDeck or Prime Peptides Calculator accept generic entries and run the same math without needing a named preset.
Why does FormBlends support U-50 and U-40 syringes when most tools only do U-100?
U-100 is the dominant standard in the U.S., but U-50 and U-40 syringes are common in other countries and occasionally show up domestically. Drawing a dose calculated for U-100 into a U-50 syringe doubles the actual volume injected. FormBlends accounts for this because the conversion factor changes depending on syringe type, and getting it wrong is a significant dosing error.
Is peptidereconstitutecalculator.com actually reliable for BPC-157, or is its narrow focus a red flag?
Narrow focus is not itself a reliability problem. The tool does one thing: convert a BPC-157 mcg dose to a U-100 syringe graduation. That math is simple and verifiable by hand. The limitation is scope, not accuracy. Cross-check the output against the manual formula in entry 12 and you’ll know immediately if something is off.
For semaglutide or tirzepatide, which free tools actually cover GLP-1 class peptides?
MyPeptideMatch is one of the few free options that handles semaglutide and tirzepatide alongside traditional healing peptides. FormBlends includes a GLP-1 preset at 50 mg. Outliyr also lists GLP-1 class options. LeadWest covers retatrutide specifically, which is notable because most tools ignore it entirely.
Sources
- U-100 syringe standardization: FDA insulin syringe guidance (publicly available)
- peptidefox.com, peptidefox.com/about (verified public)
- peptidereconstitutecalculator.com (verified public)
- peptides.org dosage reference section (verified public)
- FormBlends app listing, iOS App Store and Google Play (verified public)
- LeadWest Medical calculator page (verified public)
- Outliyr.com peptide calculator (verified public)
