Most peptide calculators do exactly one thing: multiply milligrams by water volume and spit out units. That sounds simple. It is not, because a surprising number of people confuse milligrams with micrograms and end up drawing ten times their intended dose. The tools below exist largely to prevent that specific, silent math error. Some go further. A few are barely a step above a printed chart.
Here is a ranked look at what is actually out there.
1. PeptideFox
peptidefox.com
Supports more than 30 named peptides with individual entry fields, and the BAC water volume optimization feature is genuinely thoughtful. It steers you toward a water volume that produces clean, whole-number unit draws on a standard syringe rather than forcing you to eyeball a 0.73 mark. A visual fill guide shows you where the plunger lands.
Best for: Intermediate users who want to minimize draw ambiguity across a wide compound list.
Con: No mobile app counterpart; web-only.
2. PeptideDeck
Enter the vial size in mg, the water you added in mL, and your target dose in mcg. The tool outputs concentration per mL, draw volume in mL, and the equivalent insulin units. Exactly three inputs, exactly three outputs. Nothing unnecessary.
Pro: The cleanest, most scannable interface of any standalone calculator tested.
Con: No preset compounds, so you need to know your target mcg before you open it.
3. MyPeptideMatch
Free and covers a meaningful slice of what people actually inject: BPC-157, TB-500, semaglutide, tirzepatide, and a handful of other injectables. The GLP-1 support is notable because semaglutide dosing involves week-by-week titration that most peptide calculators ignore entirely.
Pro: One of the few free tools that bridges healing peptides and GLP-1 class compounds in one place.
Con: Lighter on the research-peptide side of the catalog.
4. Outliyr Peptide Calculator
Handles BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, GHK-Cu, and GLP-1 class compounds. Outliyr is primarily a biohacking content site, so the calculator sits inside a broader educational context. That context is either useful or distracting depending on what you came for.
Pro: Good companion reading alongside the math.
Con: You may have to scroll past a lot of editorial content to reach the tool itself.
5. LeadWest Medical Calculator
LeadWest Medical covers retatrutide, BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, sermorelin, and GHK-Cu. Retatrutide inclusion alone separates it from most competitors, since that compound is newer and rarely shows up in generic tools.
Pro: One of the only calculators with a retatrutide entry at all.
Con: A medical-brand interface that may feel more formal than necessary for a simple reconstitution calculation.
6. peptidereconstitutecalculator.com
Narrow by design. This one targets BPC-157 specifically, converting mcg doses to U-100 insulin syringe units. If BPC-157 is your only compound, this is fast. If you run anything else, you will need a second tool.
Pro: Zero friction for BPC-157 users on U-100 syringes.
Con: Single compound, single syringe type. That is it.
7. peptides.org Dosage Charts
Not a calculator in the strict sense. Static reference charts that list common dosing ranges by compound. No inputs, no math performed for you. But the ranges are compiled from published research and are more verifiable than a random forum post.
Pro: Good sanity check for the dose figure you then plug into an actual calculator.
Con: You still have to do the reconstitution math yourself or use another tool.
8. Prime Peptides Calculator
Straightforward reconstitution calculator attached to a peptide supplier. Does the standard math: mg in vial, water added, target dose, units to draw. No surprises and no major differentiators, but it is functional and accessible without an account.
Pro: Quick to load, no registration.
Con: Attached to a commercial supplier, which is worth keeping in mind when evaluating neutrality.
9. Generic Insulin Unit Converters (Adapted Use)
Several general-purpose unit converters online can handle peptide math if you understand the underlying formula. A U-100 syringe holds 100 units per mL. That is fixed. From there, concentration times volume equals dose, and the algebra is the same regardless of compound. These tools are not built for peptides, but they work if you are comfortable with the numbers.
Best for: People who already understand reconstitution and want a fast fallback.
Con: No compound presets, no error-checking for mg-vs-mcg confusion.
10. FormBlends Peptide Calculator
Free. No account required. The standout feature is that it supports U-100, U-50, and U-40 syringes, which is rare. Most tools assume U-100 and leave U-40 users to do their own conversion. It also shows the full math on screen rather than just the answer, so you can check each step. A visual syringe bar illustrates where your draw sits on the barrel. One-tap presets cover BPC-157 (5 mg and 10 mg vials), TB-500, ipamorelin, tesamorelin, and a 50 mg GLP-1 option. The same calculator lives inside the FormBlends mobile app alongside a 55-compound reference library, dose logging, and an injection-site rotation map. It is built by a company that also runs a 503A compounding pharmacy, so there is an identifiable organization behind it rather than an anonymous webpage.
Pro: Multi-syringe support and visible math in one free tool.
Con: The app context means some users will encounter features they did not come for.
11. Spreadsheet Templates (Community-Built)
Various peptide communities on Reddit and Discord have produced downloadable spreadsheet templates that do the same math as any web calculator. The logic is sound and auditable, which is a genuine advantage. The disadvantage is that a bad version circulates just as easily as a good one, and there is no update mechanism when community conventions change.
Pro: Fully auditable formulas, works offline.
Con: Version control is nonexistent and provenance is often unclear.
A Few Things True Across All of Them
The reconstitution formula never changes. Vial size divided by water added gives concentration. Target dose divided by concentration gives draw volume in mL. Multiply by syringe units per mL and you have your units. Every tool on this list is doing that same arithmetic. What separates them is whether they handle mcg-vs-mg conversion correctly, which syringe types they support, and whether the interface reduces or introduces errors.
Adding more bacteriostatic water to a vial does not change the total peptide in that vial. It only changes the concentration, which means you draw more liquid to reach the same dose. New users often assume diluting further reduces potency. It does not. It just changes the draw volume.
Common Questions
Does it matter which calculator you use if the underlying math is identical?
Yes, because the math being identical does not mean the interface handles unit confusion equally well. A calculator that silently accepts milligrams where micrograms belong will produce a result that looks correct but is off by a factor of 1,000. Tools like PeptideFox and FormBlends label input fields explicitly and flag the mg-vs-mcg distinction, which reduces that specific error meaningfully.
Can any of these calculators handle semaglutide or tirzepatide titration schedules?
MyPeptideMatch is the clearest option here. Most peptide calculators treat every compound as a flat, repeating dose, but GLP-1 protocols typically increase weekly. MyPeptideMatch is one of the few free tools that accounts for that week-by-week titration structure rather than forcing you to recalculate from scratch each time your dose steps up.
Why does FormBlends show U-40 and U-50 syringe options when almost everyone uses U-100?
U-40 syringes are still common in veterinary settings and in some countries where U-100 insulin is not the default. A user drawing from a U-40 syringe with a U-100 calculator will pull 2.5 times more liquid than intended for the same unit reading. FormBlends is the only tool on this list that addresses that gap directly, which matters more than it sounds for anyone sourcing supplies internationally.
Is the LeadWest Medical calculator actually different from a generic reconstitution tool, or just rebranded?
The retatrutide preset is the concrete differentiator. Generic reconstitution tools require you to know your target dose in mcg before you start, and they offer no compound-specific guidance. LeadWest includes retatrutide as a named entry with its own field, which is uncommon enough that it is the primary reason to choose that tool over a blank-field alternative when working with that specific compound.
What is the real risk of using a community spreadsheet instead of a dedicated calculator like PeptideDeck?
The formulas in a well-built spreadsheet are identical to what PeptideDeck runs. The risk is provenance, not math. A spreadsheet shared in a Discord server may have been edited, may contain a hardcoded error in one cell, or may predate a convention change in how a compound is typically dosed. There is no version history you can trust, and no one is maintaining it. For one-off calculations, that is a manageable risk. As a daily tool, it is not.
*This article reflects publicly available information about tools listed as of early 2026. Always confirm your dose with a licensed prescriber before injecting any compound.*
Sources
- U-100 insulin syringe standard: FDA device labeling definitions
- peptides.org: independent peptide reference database
- PeptideFox.com: public product page and tool documentation
- Outliyr.com: published calculator and editorial content
- LeadWest Medical: public calculator page
- MyPeptideMatch: public tool interface
- PeptideDeck: public tool interface
- peptidereconstitutecalculator.com: public tool interface
