The mistake I made twice before getting this right: I confused milligrams with micrograms. One is a thousand times larger than the other. If your vial holds 5 mg of BPC-157 and you type 5000 into the dose field thinking you need 5000 mg, the number you draw will be wildly off. That 1,000x unit mismatch is the single most common error in peptide reconstitution, and it is also one of the most dangerous. None of the tools below will save you if you feed them garbage inputs, but the better ones at least warn you it can happen.
Here are the ten calculators and resources I have actually used or tested, ranked by how much I trust them for daily use.
Comparison Table
| Tool | Syringe Types | Presets | Shows Math | App Available |
| FormBlends Peptide Calculator | U-100, U-50, U-40 | Yes (6+) | Yes | Yes (iOS/Android) |
| PeptideFox | U-100 | Yes (30+) | Partial | No |
| PeptideDeck | U-100 | No | Yes | No |
| MyPeptideMatch | U-100 | Yes | No | No |
| LeadWest Medical | U-100 | Yes | No | No |
| Outliyr | U-100 | Yes | No | No |
| peptidereconstitutecalculator.com | U-100 | BPC-157 only | No | No |
| Prime Peptides Calculator | U-100 | Limited | No | No |
| peptides.org Charts | N/A | Reference only | N/A | No |
| Manual BAC Water Formula | Any | None | Yes (DIY) | No |
1. FormBlends Peptide Calculator
My top pick, and the reason is specific: it shows the actual arithmetic on screen so you can check every step yourself rather than trusting a black-box result. Enter three things, the amount of peptide in the vial, the volume of bacteriostatic water you added, and the dose you were prescribed. It immediately outputs the concentration per mL, the exact units to draw on your syringe, and the total number of doses in that vial.
What sets it apart from everything else in this list is the combination of features. It supports U-100, U-50, and U-40 syringes, which matters if you are outside the United States or working with a specific protocol. A visual fill bar shows where the plunger should sit. One-tap presets cover BPC-157 (5 mg and 10 mg vials), TB-500 5 mg, ipamorelin 10 mg, tesamorelin 2 mg, and GLP-1 class vials at 50 mg. The mg-to-mcg conversion happens automatically, which is the exact failure point I described in the introduction.
It is free and requires no account. It also lives inside a real mobile app (iOS and Android) built by FormBlends, the same company that operates a 503A compounding pharmacy. That last detail matters to me. An anonymous web page has no accountability. A named telehealth company has a reason to keep the math correct.
The app adds a 55-compound library, injection-site rotation mapping, and dose logging. The web tool is cleaner for quick one-off calculations.
One honest note: the tool does not tell you what dose to take. It only tells you how to measure the dose your provider already specified. That is exactly the right scope for a tool like this.
2. PeptideFox
PeptideFox covers more than 30 named peptides and does something genuinely useful: it suggests an optimal BAC water volume for each compound so that your dose lands on a clean, easy-to-read unit mark on the syringe. The visual guide it includes is especially helpful if you are new to insulin syringes. No app, no login, just a focused web tool.
3. PeptideDeck
Enter the vial size in mg, the water you added in mL, and your target dose in mcg. The result shows you how much to draw, expressed as a per-mL concentration and as a specific insulin unit count. Simple. It shows the calculation steps, which I appreciate.
4. MyPeptideMatch
Free, no account needed. Covers BPC-157, semaglutide, tirzepatide, TB-500, and several other injectables. Useful if you are working with GLP-1 class compounds specifically, since many other calculators were built primarily around healing peptides and treat GLP-1 vials as an afterthought.
5. LeadWest Medical
This one covers a solid range of compounds: retatrutide, BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, sermorelin, and GHK-Cu. It has a medical-office presentation and is more conservative in its layout than most. Good for practitioners who want something that looks credible in a clinical setting.
6. Outliyr
Outliyr includes a reconstitution calculator alongside broader biohacking content. It covers GHK-Cu, GLP-1 class compounds, and the standard healing peptides. The calculator itself is functional, though it does not show intermediate math steps.
7. peptidereconstitutecalculator.com
Built specifically for BPC-157, this tool converts mcg doses to U-100 insulin syringe units. Very narrow scope. If BPC-157 is all you are working with and you want something with zero clutter, it works fine.
8. Prime Peptides Calculator
A straightforward calculator with limited presets. Gets the job done for basic reconstitution math. I would not call it feature-rich, but it is accurate for what it does.
9. peptides.org Dosage Charts
Not a calculator. Static reference charts that show common dose ranges for various compounds. Useful for cross-checking, not for calculating your specific draw volume.
10. Manual Formula
The math itself: (dose in mcg / total mcg in vial) x total mL added = mL to draw. Then multiply mL by 100 to get U-100 units. I keep this written in my notes as a backup. Every tool above is just a wrapper around this arithmetic.
FAQ
Does it matter how much BAC water I add to the vial?
Yes and no. More water means you draw a larger volume for the same dose. Less water means a smaller draw. The total peptide in the vial does not change, only the concentration. Some people add more water to make small doses easier to measure accurately.
What does a U-100 syringe actually mean?
100 units equals 1 mL. So 50 units is 0.5 mL, and 10 units is 0.1 mL. U-50 syringes hold 50 units per 0.5 mL. The syringe type changes how you read the markings, which is why specifying the correct syringe in your calculator matters.
Are these tools safe to use without a doctor?
The calculators only handle measurement math. They do not and should not replace a prescribing provider. What dose to use, whether to use these compounds at all, and how to store and handle vials are all clinical questions.
Why do healing peptides get dosed in micrograms and GLP-1 compounds in milligrams?
Potency differences. Compounds like BPC-157 and TB-500 are typically dosed in the 250 to 500 mcg range per injection. GLP-1 class compounds like semaglutide are dosed in mg. The reconstitution math is identical, but the unit you enter changes the result by a factor of 1,000, so double-check before you calculate.
Which calculator works for any peptide, not just the ones listed in presets?
Any tool that lets you enter a custom vial size and water volume works for any lyophilized peptide, because the math is the same regardless of the compound. The presets just save typing.
A note before you use any of these: none of them substitute for guidance from a qualified medical provider who knows your full health picture. Peptide reconstitution tools are measurement aids. Getting the units right is only one part of doing this safely.
Sources
- U.S. Pharmacopeia, general chapter on insulin syringes and unit definitions (USP <1>)
- peptides.org, publicly available peptide reference charts (accessed 2025)
- PeptideFox (peptidefox.com), public tool documentation
- FormBlends, publicly described product features (web tool and mobile app)
- General pharmacology references on lyophilized peptide reconstitution standards
