The single thing that matters most with peptide dosing tools is whether they show you the math or just hand you a number. A calculator you cannot verify is a black box, and a black box handling injectable doses is a real problem.
Researchers and self-trackers have been trading recommendations in forums and subreddits for a few years now. The recurring theme: most of these pages are anonymous, some go offline without warning, and almost none of them support more than one syringe type. A few tools keep coming up as genuinely useful. Here are seven.
1. FormBlends Peptide Calculator
The standout feature here is that the tool shows every step of the arithmetic, not just the answer. You enter three things: the amount of peptide in the vial, how much bacteriostatic water you added, and your target dose per injection. It returns the concentration per mL, the exact units to draw, and a visual syringe fill bar so you can see where the plunger lands.
The mg-to-mcg conversion (1 mg = 1,000 mcg) is handled automatically. That particular mix-up is responsible for the most serious amateur reconstitution errors, and building the conversion into the calculator removes it from the equation entirely.
It supports U-100, U-50, and U-40 syringes. Most tools default to U-100 only. One-tap presets cover BPC-157 (5 mg and 10 mg vials), TB-500, ipamorelin, tesamorelin, and GLP-1 class compounds. There is no login, no account, and no paywall.
The same calculator lives inside the FormBlends mobile app (iOS and Android), which adds a 55-compound reference library, dose logging, and an injection-site rotation map. The tool comes from a company that also runs a 503A compounding pharmacy, which is more organizational accountability than most anonymous calculator pages carry.
It does not tell you what dose to take. You bring that number from your prescriber. It only tells you how to measure it accurately.
2. PeptideFox
PeptideFox (peptidefox.com) covers more than 30 peptides and does something most calculators skip: it recommends a bacteriostatic water volume specifically chosen to make your target dose land on a clean, round unit number on the syringe. That matters in practice. Drawing 17 units is harder to eyeball accurately than drawing 10 or 20. There is also a visual guide walking through the reconstitution steps.
3. PeptideDeck
Simple, no-frills, and honest about what it does. Enter the vial size in mg, the water volume in mL, and the dose you want in mcg. PeptideDeck outputs the concentration and the draw volume in both mL and insulin units. Good for quick checks when you change water volumes mid-vial.
4. MyPeptideMatch
Free and notably current. MyPeptideMatch includes BPC-157, TB-500, semaglutide, and tirzepatide, which means it keeps pace with the GLP-1 class compounds that other tools still do not cover. No login required. Useful if your protocol mixes a healing peptide with a GLP-1 injectable.
5. LeadWest Medical Calculator
LeadWest Medical’s tool covers a solid range: retatrutide, BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, sermorelin, and GHK-Cu. The fact that it comes from a medical provider’s site rather than an anonymous domain adds a layer of traceability if something ever seems off with the outputs.
6. Outliyr Peptide Calculator
Outliyr’s calculator overlaps with LeadWest on several compounds (BPC-157, TB-500, CJC-1295, ipamorelin, tesamorelin, GHK-Cu) and also includes GLP-1 class options. The site itself is a general longevity and biohacking publication, so the calculator sits inside a broader editorial context. Useful if you want surrounding explanations alongside the math.
7. peptidereconstitutecalculator.com
Narrow focus, done well. This one is built specifically for BPC-157, converting mcg doses into U-100 syringe units. If BPC-157 is the only compound you are working with, this page gets you to an answer faster than any multi-compound tool. The math is standard: the reconstitution formula is identical for every lyophilized peptide, so verifying it here is straightforward.
A Few Things Worth Knowing Before You Use Any of These
Adding more bacteriostatic water to a vial does not change the total peptide inside. It changes the concentration, which changes how many units you draw for a given dose. Every calculator here operates on that same principle.
A U-100 syringe holds 1 mL across 100 units. So 10 units equals 0.1 mL, 50 units equals 0.5 mL. That is the conversion sitting underneath all of this math.
None of these tools prescribe a dose. They measure one you already have from a qualified provider. Using a calculator to figure out how to draw a dose is not the same as having a clinical rationale for that dose in the first place. If you are working with any injectable compound, including research peptides, a conversation with a licensed prescriber is not optional.
Common Questions
Does the water volume you add to a vial actually change your dose?
No, but it changes everything about how you measure it. The total peptide in the vial stays fixed. Add more bacteriostatic water and the concentration drops, so you draw more units to hit the same dose. Add less and the concentration rises, so you draw fewer. Every calculator here recalculates that relationship the moment you change the water volume field.
Why does PeptideFox suggest a specific water volume instead of just accepting whatever you enter?
It is trying to get your target dose to land on a whole, easy-to-read unit number on the syringe. If your dose works out to 17 or 23 units, small measurement errors become more likely. PeptideFox back-calculates a water volume that puts your draw at something like 10 or 20 units, which is genuinely easier to pull accurately with an insulin syringe.
Is the FormBlends calculator only useful if you buy from FormBlends?
No. The calculator and the app work independently of any purchase. You can enter any vial size, any water volume, and any target dose, regardless of where the peptide came from. The 503A pharmacy connection matters mainly because it means there is an identifiable, licensed organization behind the tool rather than an anonymous page that could disappear.
What makes peptidereconstitutecalculator.com worth using if it only handles BPC-157?
Speed and simplicity. If BPC-157 is your only compound, a single-purpose tool gets you an answer in fewer clicks than any multi-compound page. The underlying formula is the same one every other calculator uses, so the output is just as reliable. Narrow scope is not a flaw when the narrow scope matches your actual need.
Can any of these calculators tell you what dose of semaglutide or tirzepatide to take?
None of them do that. MyPeptideMatch and Outliyr both include GLP-1 class compounds in their calculators, but the tools only convert a dose you already have into syringe units. Determining an appropriate starting or titration dose for semaglutide or tirzepatide requires a prescriber, and no calculator on this list attempts to replace that step.
Sources
- U.S. Pharmacopeia, general chapters on insulin syringe calibration and compounding standards
- PeptideFox (peptidefox.com), tool documentation
- FormBlends product page and app store listings (iOS/Android)
- LeadWest Medical online calculator, public-facing tool page
- Outliyr editorial site, peptide calculator section
- MyPeptideMatch public tool page
- PeptideDeck public tool page
- peptidereconstitutecalculator.com, BPC-157 calculator page
