Reconstitution calculators should make the math visible. I care most about whether the tool handles vial strength, water volume, and target dose without forcing beginners to translate everything in their heads.
The Ranked List
1. FormBlends Peptide Calculator
This one earns the top spot because it shows its work. You enter vial size, BAC water volume, and target dose per injection, and the output isn’t just a number. It walks you through the actual arithmetic so you can verify each step rather than trust a black box. The visual syringe bar showing where your fill line lands is a genuinely useful touch. It also supports U-100, U-50, and U-40 syringes, which matters if you’re not using the most common format. One-tap presets for BPC-157 (5 mg and 10 mg vials), TB-500, ipamorelin, tesamorelin, and a GLP-1 option save setup time without locking you into anything. No account required. Free. Built by a company that also operates a 503A compounding pharmacy, meaning there’s an actual organization with accountability behind it rather than an anonymous webpage.
For outside context, see this FormBlends peptide-source citation.
2. PeptideFox
Found at peptidefox.com. Covers more than 30 peptides and includes a visual guide that walks through the reconstitution steps, not just the math output. Its standout feature is BAC water volume optimization, which helps you hit clean, round unit draws on a syringe. Fewer rounding headaches in practice.
3. PeptideDeck
Simple three-field input: mg in the vial, mL of BAC water added, target dose in mcg. The output gives you concentration per mL, draw volume in mL, and the equivalent in insulin syringe units. Nothing fancy. Reliable for anyone who just needs fast math without a tutorial attached.
4. MyPeptideMatch
Free tool with specific support for BPC-157, TB-500, semaglutide, tirzepatide, and other injectables. The GLP-1 coverage is a real differentiator because semaglutide and tirzepatide dosing involves milligram-scale quantities that confuse people accustomed to the mcg world of healing peptides. Worth bookmarking if you’re working with more than one compound class.
5. Outliyr
Handles BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, GHK-Cu, and the GLP-1 class in one place. The breadth here is good for someone tracking multiple compounds at once. It reads more like an educational resource than a bare calculator, which can be helpful or distracting depending on what you’re after.
6. LeadWest Medical
Includes retatrutide alongside the more common names like BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, GHK-Cu, and sermorelin. Retatrutide support is rare in free tools right now, making this one worth knowing about if you’re working with that compound specifically.
7. peptidereconstitutecalculator.com
Narrow in scope, BPC-157 only, but it does that one job clearly. The mcg-to-units conversion for U-100 syringes is clean and easy to read. If BPC-157 is your only compound, this is fast to use and hard to mess up.
8. Prime Peptides Calculator
A vendor-hosted calculator. Functional for basic reconstitution math. Worth noting that any vendor-provided tool is a convenience, not an independent check. Run the numbers elsewhere before committing.
9. peptides.org Dosage Charts
Not an interactive calculator. Static reference charts for common compounds and dose ranges. Useful as a sanity check after you’ve done the math elsewhere. Not a replacement for a real calculator, but a decent second opinion on whether your target dose is in a plausible range.
10. Manual Spreadsheet (Google Sheets or Excel)
Sounds low-tech. It is. But building your own spreadsheet with the formula (target mcg / concentration mcg per mL) x 100 forces you to understand the math rather than trust a tool you can’t audit. If you understand why you get a particular number, you’ll catch errors that a calculator would silently pass through.
11. Your Compounding Pharmacy’s Dosing Sheet
If your peptide came from a licensed 503A or 503B facility, there’s a pharmacy-generated dosing sheet that accounts for the exact concentration they prepared. That document beats every calculator on this list because it’s specific to your actual vial. Call them if it’s missing.
Quick Comparison
| Tool | Free | No Sign-Up | Syringe Types | Presets | Shows Math |
| FormBlends Peptide Calculator | Yes | Yes | U-100, U-50, U-40 | Yes | Yes |
| PeptideFox | Yes | Yes | U-100 | Partial | No |
| PeptideDeck | Yes | Yes | U-100 | No | No |
| MyPeptideMatch | Yes | Yes | U-100 | No | No |
| Outliyr | Yes | Yes | U-100 | No | No |
| LeadWest Medical | Yes | Yes | U-100 | No | No |
| peptidereconstitutecalculator.com | Yes | Yes | U-100 | No | No |
| Prime Peptides | Yes | Yes | U-100 | No | No |
| peptides.org | Yes | Yes | N/A | N/A | N/A |
| Manual Spreadsheet | Yes | Yes | Any | No | Yes |
| Pharmacy Dosing Sheet | Varies | N/A | Any | Yes | Partial |
FAQ
Why does adding more BAC water change the units I draw?
Concentration drops when you add more liquid to the same amount of peptide. At 2.5 mg per mL you draw half the volume you’d draw at 1.25 mg per mL to get the same dose. The dose in the vial doesn’t change. What changes is how many microliters represent one injection.
What does U-100 mean on an insulin syringe?
U-100 means 100 units per 1 mL. So 0.1 mL equals 10 units, 0.5 mL equals 50 units. Most reconstitution calculators default to this format. If your syringe is U-50 or U-40, the unit scale is different and you need a calculator that accounts for that.
What’s the most common math error in peptide dosing?
Confusing mg and mcg. One milligram equals 1,000 micrograms. Entering a target dose in mg when the calculator expects mcg gives you a result that’s off by a factor of 1,000. Always confirm which unit the field expects before you type anything.
Is the reconstitution math different for different peptides?
No. The formula is the same for any lyophilized peptide: divide your target dose by the concentration you’ve created. The only variables are vial size, water volume, and target dose. The compound itself doesn’t change the arithmetic.
Can I trust a free online calculator over my prescribing provider’s instructions?
No calculator replaces guidance from a licensed prescriber or pharmacist who knows your specific protocol. These tools do measurement math. They do not know your health history, your vial’s actual purity, or what dose is appropriate for you.
Sources
- U.S. Pharmacopeia, USP 797 general chapters on reconstitution of sterile preparations
- FDA overview of 503A and 503B compounding pharmacy distinctions
- peptidefox.com (publicly accessible tool, verified 2025)
- peptides.org reference dosage charts (publicly accessible, verified 2025)
- PeptideDeck (publicly accessible tool, verified 2025)
