You’ve got a vial of BPC-157, a bottle of bacteriostatic water, and a pack of insulin syringes. The vendor says 5 mg per vial. Your protocol says 250 mcg per injection. Now what? The math sounds simple until you realize you’re converting milligrams to micrograms, figuring out how much BAC water to add, and trying to read a syringe marked in units, not milliliters. One decimal place off and you’ve drawn ten times the intended dose. This is exactly the situation a good dosing tool exists to prevent.
I went through every free peptide calculator I could find, used them on the same test case (5 mg BPC-157, 2 mL BAC water, 250 mcg target dose), and ranked them on accuracy, transparency, and whether a real person built and maintains them.
What I Looked At
- Math transparency: Does it show the formula, or just spit out a number?
- Syringe type support: U-100 only, or does it handle U-50 and U-40 too?
- mg/mcg conversion: The 1000x mistake kills people. Does the tool guard against it?
- Peptide coverage: Generic calculator or locked to one compound?
- Who built it: Named company or anonymous page?
- Extras: Logging, presets, mobile access.
The 10 Best Free Peptide Dosing Tools
1. FormBlends Peptide Calculator
Free, no account needed, and it supports U-100, U-50, and U-40 syringes, which already sets it apart from most tools on this list. You enter three things: peptide amount in the vial, BAC water volume you added, and your target dose per injection. It immediately outputs the draw volume in units for your syringe type, the concentration per mL, and the total number of doses in the vial. Then it shows the actual arithmetic so you can confirm the numbers yourself rather than just trust a black box.
The mg-to-mcg conversion is handled automatically. That matters more than it sounds. Confusing 5 mg with 5 mcg (a factor of 1000) is far and away the most common peptide math error, and this tool was built specifically to eliminate it. One-tap presets cover BPC-157 at 5 mg and 10 mg, TB-500 at 5 mg, ipamorelin at 10 mg, tesamorelin at 2 mg, and GLP-1 formulations at 50 mg. A visual syringe fill bar shows exactly where your plunger lands. The tool also explains, clearly, that adding more water changes how many units you draw without changing the total peptide delivered, which is a concept that trips up a lot of first-timers.
FormBlends is a real telehealth and 503A pharmacy company, not an anonymous web page, and the same calculator is baked into their iOS and Android app alongside a 55-compound reference library, dose logging, and an injection-site rotation map. The web version works on any browser. It does not recommend doses. You bring your provider’s protocol; it handles the measurement math.
2. PeptideFox
PeptideFox (peptidefox.com) supports over 30 named peptides and does something smart with water volume: it suggests a BAC water amount that keeps your draw landing on a clean unit mark on the syringe. Messy mid-unit draws are one of the real-world frustrations with generic calculators, and this tool actually thinks about that. A visual guide walks through the reconstitution steps alongside the numbers. Good for people who want the tool to suggest setup, not just confirm it.
3. MyPeptideMatch
This one covers an unusually broad range of injectable compounds, including BPC-157, TB-500, semaglutide, tirzepatide, and other GLP-1 class peptides. Free, no login. If you’re working with a weight-management protocol alongside a healing peptide, this is one of the few single-page tools that handles both without forcing you to switch calculators. Coverage breadth is its main strength.
4. LeadWest Medical Calculator
LeadWest Medical offers a calculator built around the specific compounds their clinic works with: retatrutide, BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, sermorelin, and GHK-Cu. Because it’s attached to a medical provider, the framing is a bit more clinical than a generic hobbyist tool. It covers most of the common research peptides in one place. Worth bookmarking if you’re on any of those compounds specifically.
5. Outliyr Peptide Calculator
The Outliyr tool includes compound-specific fields for BPC-157, TB-500, ipamorelin, CJC-1295, tesamorelin, GHK-Cu, and GLP-1 class compounds. The site itself leans heavily toward biohacking content, and the calculator sits within that context. Functional for the listed peptides. It won’t win any design awards, but the math works and the compound list covers most of what people actually use.
6. PeptideDeck
PeptideDeck takes a minimal, fill-in-the-blank approach. Enter your vial size in mg, BAC water volume in mL, and target dose in mcg. It outputs concentration, draw volume in mL, and the equivalent in insulin syringe units. No presets, no frills. That simplicity is actually a feature if you already know your numbers and just want the output fast. The unit conversion display is clear.
7. peptidereconstitutecalculator.com
This site is purpose-built for BPC-157 on U-100 syringes. It converts your target dose in mcg directly to the unit mark you draw to. Narrow scope, but if BPC-157 is all you’re working with, the focused design means fewer things to configure. It won’t help you with any other peptide. One tool, one job.
8. Prime Peptides Calculator
Prime Peptides includes a dosing calculator alongside their product catalog. Useful for customers already buying from them, since the vial sizes match their product specs. As with any vendor-side tool, confirm the math independently before relying on it for anything outside their own product line.
9. peptides.org Dosage Charts
Static reference material rather than an interactive tool. peptides.org publishes dosage charts for common compounds, typical dose ranges (BPC-157 is commonly run at 250 to 500 mcg per injection, for reference), and general reconstitution guidance. Good for cross-referencing whether your protocol is in a normal range before you start calculating units.
10. Manual Spreadsheet (Google Sheets)
Worth putting on the list honestly. The reconstitution formula is the same for every lyophilized peptide: (target dose in mcg / total peptide in mcg) x BAC water volume in mL x 100 = units to draw on a U-100 syringe. A simple spreadsheet with that formula does everything the anonymous web tools do, and you can audit every cell. No internet dependency. No risk that the page goes offline. If you’re technically comfortable, building your own takes about ten minutes and you’ll understand the math cold.
How to Choose
Single peptide, first time? Start with FormBlends for the visual confirmation and shown math, or peptidereconstitutecalculator.com if it’s BPC-157 only. Multiple compounds? PeptideFox or MyPeptideMatch cover more ground. Already know the formula and want speed? PeptideDeck or a spreadsheet. The underlying math is identical across all of them. What varies is whether the tool helps you catch your own mistakes before you inject.
A brief note: none of these tools, including this article, constitutes medical advice. Work with a qualified provider on your protocol. These calculators handle measurement, not medicine.
Common Questions
Does it matter which free calculator I use if the formula is the same across all of them?
It matters for error prevention, not the formula itself. Tools like FormBlends show the arithmetic step by step and auto-convert mg to mcg, which catches the most common mistake before it happens. A tool that just outputs a number gives you no way to spot a typo or a wrong unit entry.
Why does FormBlends include syringe presets for specific peptides like ipamorelin and tesamorelin when most calculators are generic?
Presets eliminate one input step and reduce the chance of entering a vial size wrong. FormBlends is a 503A pharmacy, so their presets reflect actual dispensed vial sizes rather than theoretical ones. That alignment between real product specs and calculator defaults is more useful than it first appears.
If I change how much BAC water I add to a vial, does that affect the dose I get per injection?
No, and this is a point several tools explain poorly. Adding more BAC water dilutes the concentration, so you draw more volume per dose, but the total peptide in the vial stays the same. PeptideFox’s approach of suggesting a water volume that lands on a clean syringe unit mark is the practical answer to this confusion.
Can I use MyPeptideMatch for both a GLP-1 peptide like semaglutide and BPC-157 on the same session?
Yes. MyPeptideMatch covers both GLP-1 class compounds and healing peptides like BPC-157 and TB-500 in one tool without requiring you to switch pages. That dual coverage is its clearest advantage over single-purpose calculators, which is worth knowing if your protocol includes more than one compound type.
Is peptidereconstitutecalculator.com worth using if I might add other peptides to my protocol later?
Probably not as your long-term default. It does one thing well: BPC-157 on U-100 syringes. The moment you add a second compound, you need a different tool. Starting with FormBlends, PeptideFox, or a personal spreadsheet gives you a setup that scales without switching calculators mid-protocol.
Sources
- U-100 insulin syringe specification: standard pharmacological reference (100 units = 1 mL)
- PeptideFox feature description: peptidefox.com (publicly viewable, 2025)
- FormBlends app and calculator feature set: FormBlends public product pages and app store listings
- BPC-157 common dosing ranges: peptides.org reference charts
- LeadWest Medical calculator: LeadWest Medical public website (2025)
- MyPeptideMatch: mypeptidematch.com public tool (2025)
- Outliyr calculator: outliyr.com public tool (2025)
