Most peptide dosing tools are a single anonymous HTML page with no update date, no company name, and math you can’t verify. That’s a strange thing to trust when a 1000x unit conversion error is entirely possible. The good news is that a handful of tools actually show their work, cover more than one peptide, or come from a source you can trace back to a real organization.
Here is the shortlist, ranked by how much I’d actually rely on them.
1. FormBlends Peptide Calculator
The one thing that sets this tool apart from every other entry on this list: it shows the underlying math on screen, so you can check the calculation yourself rather than blindly accepting an output. Most tools give you a number. This one gives you the number and the reasoning behind it.
It handles the mg-to-mcg conversion automatically, which matters because conflating the two by a factor of 1,000 is far and away the most common reconstitution mistake. It also explains, in plain language, why adding more bacteriostatic water to a vial changes the units you draw while leaving the total dose in the vial unchanged. That distinction trips up a lot of people.
Supports U-100, U-50, and U-40 syringes. Visual syringe fill bar. One-tap presets for BPC-157, TB-500, ipamorelin, tesamorelin, and GLP-1 class peptides. Free, no account required.
It is built by a named telehealth company running a 503A compounding pharmacy, which is more accountability than you get from a nameless calculator page.
2. PeptideFox
peptidefox.com covers more than 30 individual peptides, which is the widest species count on this list. Its standout feature is BAC water volume optimization: it suggests an amount of reconstitution water that produces clean, whole-unit draws on a standard insulin syringe. Less mental rounding. Comes with a visual draw guide.
3. MyPeptideMatch
Free, no login, covers BPC-157, semaglutide, tirzepatide, and TB-500, among others. One of the few free tools that explicitly handles GLP-1 class peptides alongside the older healing/recovery compounds. Straightforward layout with no friction.
4. LeadWest Medical
Covers a solid spread: retatrutide, BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, sermorelin, and GHK-Cu. The medical branding suggests a clinical context, which may make it a more comfortable starting point for practitioners. Worth checking if you are working with tesamorelin or sermorelin specifically, since not every tool includes those two.
5. Outliyr
Covers BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, GHK-Cu, and GLP-1 peptides. Similar compound coverage to LeadWest. The site skews toward the biohacker audience rather than a clinical one, which affects how the surrounding content is framed, but the calculator math itself is the same as everywhere else.
6. PeptideDeck
Clean input structure: you enter the vial amount in mg, the BAC water volume in mL, and your target dose in mcg. It outputs concentration per mL, draw volume, and insulin units. Simple. That explicit three-field format is good for learning the logic of reconstitution from scratch.
7. peptidereconstitutecalculator.com
BPC-157 only. Narrow scope, but it does the mcg-to-units conversion for U-100 syringes cleanly. If BPC-157 is the only compound you are working with and you want a single-use bookmark, this does the job without distraction.
8. Prime Peptides Calculator
Hosted by a vendor, which is worth noting since vendor-hosted tools have an obvious commercial context. The math, however, is the same universal reconstitution formula every tool uses. Check the output against a second source if you want confirmation.
9. peptides.org Dosage Charts
Not an interactive calculator. Static reference charts for common compounds, useful for cross-checking typical dose ranges (BPC-157 and TB-500 are generally dosed in the 250 to 500 mcg range per injection). Good for orientation, not for syringe-draw precision.
See also: How Big Data Is Changing Business Decisions
10. Spreadsheet Templates (Community-Built)
Various forums have published shared Google Sheets and Excel templates that do the same reconstitution math. Transparent by nature since you can inspect every formula cell. The downside is version drift: a sheet from 2021 may have outdated defaults or no maintenance.
11. Manual Calculation
The formula is not complicated. Concentration (mcg/mL) = vial content (mcg) divided by water added (mL). Units to draw = target dose (mcg) divided by concentration (mcg/mL), multiplied by 100 for a U-100 syringe. Doing this once by hand, then checking it against a tool, is the most reliable approach of all.
A note on all of these: none of them tell you what dose to take. They measure. Dose decisions belong with a qualified provider.
Common Questions
Does it matter which syringe type you select in a tool like FormBlends or PeptideDeck?
Yes, significantly. A U-100 syringe has 100 units per mL. A U-40 has 40. Select the wrong one and your draw volume calculation is off by a factor of 2.5. FormBlends explicitly supports all three common types. PeptideDeck’s output is expressed in insulin units, so confirm which syringe you are using before drawing.
Why does PeptideFox suggest a specific BAC water volume instead of letting you enter any amount?
It back-calculates from the syringe’s unit markings. The goal is a concentration that lands your target dose on a clean tick mark, say 10 units rather than 9.7, reducing the chance of a small measurement error compounding over repeated doses. It is a practical convenience, not a safety requirement.
Can MyPeptideMatch or LeadWest Medical be used for semaglutide and tirzepatide, or only older peptides?
MyPeptideMatch explicitly covers semaglutide and tirzepatide alongside BPC-157 and TB-500. LeadWest lists retatrutide, which is a newer GLP-1/GIP/glucagon triple agonist, but its public compound list does not prominently feature semaglutide. If GLP-1 class peptides are your focus, MyPeptideMatch or FormBlends are the cleaner starting points.
Are vendor-hosted calculators like Prime Peptides doing different math than independent tools?
No. The reconstitution formula is fixed: concentration equals vial content divided by water volume. Every tool on this list uses the same arithmetic. The difference is context and accountability, not calculation. Cross-checking any vendor tool against FormBlends or manual math takes about 30 seconds and removes any doubt.
What is the real risk of skipping a calculator and eyeballing the draw?
The math feels simple until it isn’t. A 5 mg vial of BPC-157 reconstituted in 2 mL gives 2,500 mcg/mL. A common 250 mcg dose is exactly 10 units on a U-100 syringe. Miss the water volume by 0.5 mL and that same draw delivers 357 mcg instead. Small input errors produce meaningful dose errors, which is the entire reason these tools exist.
Sources
- U-100 syringe volume standard: FDA insulin labeling and pharmacology references
- Reconstitution math principles: general compounding pharmacy references
- PeptideFox compound count and features: peptidefox.com (publicly listed)
- MyPeptideMatch compound list: mypeptidematch.com (publicly listed)
- LeadWest Medical calculator compound list: leadwestmedical.com (publicly listed)
- Outliyr peptide calculator compound list: outliyr.com (publicly listed)
- PeptideDeck input/output structure: peptidecks.com (publicly listed)
- peptidereconstitutecalculator.com scope: site content (publicly listed)
- peptides.org dosage reference charts: peptides.org (publicly listed)
