Peptide Calculator
Divide the mg in your vial by the mL of bacteriostatic water to get the concentration, then divide your dose by it. Example: 5 mg in 2 mL = 2.5 mg/mL, so 250 mcg is 0.10 mL — 10 units on a U-100 insulin syringe.
Peptide Reconstitution & Dosage Calculator
- ✔ Standard pharmacy dilution math
- ✔ U-100, U-40 & mL syringes
- ✔ 28-day USP <797> check
- ✔ Blends of up to 3 peptides
- ✔ Shareable link & step-by-step math
- ✔ Lab mode: molarity & molecular weight
Math tool, not medical advice. This calculator converts the numbers you enter into a volume and a syringe reading. It does not suggest a dose. Use it only to check a dose prescribed or specified by a licensed clinician, and confirm every reading with your pharmacist.
Peptide Reconstitution & Dosage Calculator
Three modes in one tool: convert a dose into syringe units, work backwards to find how much BAC water to add, or calculate a multi-peptide blend. Results update as you type.
= 0.100 mL of a 2.5 mg/mL solution · lands exactly on a printed mark
Show the math for your numbers
- Enter your values to see each step.
Mixing plan & vial check
how to add the waterWhat’s in a syringe reading?
reverse lookupWhat each injection contains
blend breakdown| Peptide | In vial | Per injection | Concentration |
|---|
28-day vial timeline
each block = 1 dayBAC water optimizer
same vial, same dose — different water| Water | Concentration | Your draw | Readability |
|---|
Green rows land your dose on a printed syringe mark.
Your vial label
Peptide mcg to Units: Quick Answers
The most-searched conversions, worked out for the two most common mixes. On a U-100 insulin syringe, 1 unit is always 0.01 mL — only the amount of peptide inside each unit changes with your mix.
How many units is 100 mcg?
4 units in a 5 mg vial mixed with 2 mL, or 2 units in a 10 mg vial mixed with 2 mL.
How many units is 250 mcg?
10 units in a 5 mg vial with 2 mL, or 5 units in a 10 mg vial with 2 mL.
How many units is 500 mcg?
20 units in a 5 mg vial with 2 mL, or 10 units in a 10 mg vial with 2 mL.
How many units is 1 mg?
40 units in a 5 mg vial with 2 mL, or 20 units in a 10 mg vial with 2 mL.
How many mcg is 10 units?
250 mcg in a 5 mg vial with 2 mL, or 500 mcg in a 10 mg vial with 2 mL.
How many mL is 10 units?
0.10 mL on any U-100 syringe, whatever the peptide. On a U-40 syringe, 10 units is 0.25 mL.
What Is a Peptide Calculator?
A peptide calculator is a dilution tool that turns three numbers — the milligrams of peptide in a vial, the millilitres of bacteriostatic water added, and the dose per injection — into the exact volume (mL) and insulin-syringe units to draw. It works for any lyophilized (freeze-dried) peptide because the math depends only on mass and volume, not on the compound.
Searchers call it many things: a peptide reconstitution calculator, peptide dosage calculator, peptide dose calculator, peptide mixing calculator, BAC water calculator or peptide syringe calculator. They all solve the same problem. The vial is labelled in milligrams, the dose is usually written in micrograms, and the syringe is marked in units. Three different scales meet in one small barrel, and that is where errors happen.
In nine years of writing about supplements and checking dose math at the pharmacy counter, the mistakes I see most often are not exotic. They are a misplaced decimal, a U-40 syringe read as U-100, or a dose that falls between two tick marks. This tool is designed to catch all three before the needle goes in the vial.
How to Use This Peptide Reconstitution Calculator
- Choose a mode. Dose → Units is the standard peptide dosage calculator. Find BAC Water works backwards from the syringe mark you want. Blend handles vials that contain two or three peptides.
- Enter the vial strength in mg exactly as printed on the label. Presets fill only this field — they never set a dose.
- Enter the bacteriostatic water you added (or will add). Use the quick chips for common volumes.
- Enter your dose and choose mcg or mg. Switching the unit converts the number automatically, so 250 mcg becomes 0.25 mg.
- Select the syringe you physically have. A 0.3 mL, 0.5 mL and 1 mL U-100 syringe all read 100 units per mL, but their tick spacing differs — and a U-40 syringe reads completely differently.
- Read the result, then check the alerts. The tool flags draws that fall between marks, exceed the syringe, or run past the 28-day window. Copy or print the summary and the vial label.
Peptide Reconstitution Formula
Every result on this page comes from the same three lines of standard pharmacy dilution math:
Concentration (mcg/mL) = vial mg × 1,000 ÷ water mL
Volume to draw (mL) = dose mcg ÷ concentration (mcg/mL)
Syringe units = volume mL × 100 (U-100) or × 40 (U-40)
Worked example (the calculator’s default)
A 5 mg vial of BPC-157 mixed with 2 mL of bacteriostatic water, dose 250 mcg, U-100 syringe:
- 5 × 1,000 ÷ 2 = 2,500 mcg/mL (2.5 mg/mL)
- 250 ÷ 2,500 = 0.10 mL
- 0.10 × 100 = 10 units
- 5,000 ÷ 250 = 20 doses — 20 days at once daily, inside the 28-day window
The “units per mcg” shortcut
On a U-100 syringe, each unit holds concentration ÷ 100. At 2,500 mcg/mL, one unit = 25 mcg, so 250 mcg = 10 units.
The popular “add a zero” rule — 1 mL of water for every 10 mg of peptide — always gives 10 mg/mL, or 100 mcg per unit. It is easy to remember, but it can make small doses very hard to measure. The optimizer above shows you a better water volume for your dose.
Peptide Reconstitution Chart (U-100 Units)
Common vial sizes and water volumes, with the syringe reading for four example doses. Values come from the same formula the calculator uses.
| Vial + water | Concentration | 100 mcg | 250 mcg | 500 mcg | 1 mg |
|---|---|---|---|---|---|
| 2 mg + 1 mL | 2 mg/mL | 5 u | 12.5 u | 25 u | 50 u |
| 2 mg + 2 mL | 1 mg/mL | 10 u | 25 u | 50 u | 100 u |
| 5 mg + 1 mL | 5 mg/mL | 2 u | 5 u | 10 u | 20 u |
| 5 mg + 2 mL | 2.5 mg/mL | 4 u | 10 u | 20 u | 40 u |
| 5 mg + 3 mL | 1.67 mg/mL | 6 u | 15 u | 30 u | 60 u |
| 10 mg + 1 mL | 10 mg/mL | 1 u | 2.5 u | 5 u | 10 u |
| 10 mg + 2 mL | 5 mg/mL | 2 u | 5 u | 10 u | 20 u |
| 10 mg + 3 mL | 3.33 mg/mL | 3 u | 7.5 u | 15 u | 30 u |
| 15 mg + 3 mL | 5 mg/mL | 2 u | 5 u | 10 u | 20 u |
| 20 mg + 2 mL | 10 mg/mL | 1 u | 2.5 u | 5 u | 10 u |
“u” = units on a U-100 insulin syringe (100 units = 1 mL). Readings under 5 units are hard to measure accurately — add more water if your protocol allows.
How Much Bacteriostatic Water to Add to a Peptide Vial
There is no single correct volume. Water does not change how much peptide is in the vial — it only changes how concentrated the solution is, and therefore how big each draw looks on the syringe. A practical rule I use when checking a mix: aim for a dose that lands between 10 and 50 units on a whole printed mark. That range is large enough to read accurately and small enough to inject comfortably.
How much BAC water for a 5 mg peptide?
With 2 mL, a 5 mg vial is 2.5 mg/mL and each U-100 unit is 25 mcg — 250 mcg reads 10 units and 500 mcg reads 20 units. With 1 mL, the same 250 mcg shrinks to 5 units, which is harder to read.
How much BAC water for a 10 mg peptide?
With 2 mL, a 10 mg vial is 5 mg/mL (50 mcg per unit). With 1 mL it is 10 mg/mL (100 mcg per unit). For GLP-1 vials measured in mg, the prescriber or compounding pharmacy usually specifies the volume — follow their label, and use the semaglutide reconstitution calculator or tirzepatide units calculator for the titration steps.
🧪 Pharmacist’s note: bacteriostatic vs sterile water
Bacteriostatic water for injection contains 0.9% benzyl alcohol, a preservative that allows the vial to be entered more than once. Sterile water for injection has no preservative and is intended for single use. Benzyl alcohol is not suitable for neonates. Under USP <797>, a preserved multiple-dose container generally carries a 28-day beyond-use date after first puncture unless the manufacturer’s labelling says otherwise — which is why this calculator prints a discard-by date.
Add water slowly down the inside wall of the vial, then swirl gently. Do not shake. Store reconstituted vials refrigerated (2–8 °C), protected from light, and never freeze them unless the product label says you can.
Insulin Syringe Units Explained: U-100 vs U-40
“Units” on an insulin syringe are a volume scale, not a peptide dose. On a U-100 syringe, 100 units equals 1 mL, so 1 unit = 0.01 mL — whether the syringe holds 0.3 mL, 0.5 mL or 1 mL. A U-40 syringe packs only 40 units into the same 1 mL. Reading a U-100 number on a U-40 barrel gives you 2.5 times the volume you intended.
| Volume | U-100 reading | U-40 reading | Best syringe for this draw |
|---|---|---|---|
| 0.02 mL | 2 units | 0.8 units | 0.3 mL U-100 (½-unit marks) |
| 0.05 mL | 5 units | 2 units | 0.3 mL U-100 |
| 0.10 mL | 10 units | 4 units | 0.3 or 0.5 mL U-100 |
| 0.25 mL | 25 units | 10 units | 0.3 or 0.5 mL U-100 |
| 0.50 mL | 50 units | 20 units | 0.5 or 1 mL U-100 |
| 1.00 mL | 100 units | 40 units | 1 mL U-100 |
Tick spacing varies by brand. Most 0.3 mL syringes mark every ½ or 1 unit; most 1 mL syringes mark every 2 units. Always confirm against the barrel in your hand.
How to Reconstitute a Peptide, Step by Step
The math is only half the job. Clean technique keeps a multi-dose vial safe for its full 28 days. These are the same steps used for any lyophilized (freeze-dried) injectable powder.
- Gather clean supplies. Wash your hands. Set out the peptide vial, bacteriostatic water, alcohol swabs, a syringe for adding water, your dosing syringes and a sharps container.
- Let the vial reach room temperature. If the powder was refrigerated, give it a few minutes on the counter so the water mixes evenly.
- Swab both rubber stoppers. Wipe the peptide vial and the water vial with an alcohol swab and let them air-dry. Don’t blow on them.
- Draw the bacteriostatic water. Draw the volume from the calculator. If it’s more than your syringe holds, the mixing plan above tells you how many draws to make.
- Add the water slowly down the side. Angle the needle so the water runs down the inside wall of the vial, not straight onto the powder. Go slowly to avoid foaming.
- Swirl gently until clear. Roll or swirl the vial — never shake it. Most peptides dissolve within a minute or two; some take longer.
- Label, refrigerate and inspect. Copy the vial label from the calculator, store the vial at 2–8 °C, and check it before every use. Discard it if it turns cloudy, has particles or changes colour (copper peptides such as GHK-Cu are normally blue), or once it reaches its discard-by date.
Use a new sterile needle for every entry, never share syringes, and dispose of sharps in a proper container.
Common Peptide Reconstitution Ratios
Typical vial sizes and water volumes seen for popular peptides, with what one syringe unit holds. Tap Load in calculator to fill in the vial and water — your dose always comes from your own prescription or protocol, so it is never pre-filled.
| Peptide | Example mix | Concentration | Per U-100 unit | Open | Dedicated tool |
|---|---|---|---|---|---|
| BPC-157 | 5 mg + 2 mL | 2.5 mg/mL | 25 mcg | Load in calculator | BPC-157 calculator |
| TB-500 | 5 mg + 2 mL | 2.5 mg/mL | 25 mcg | Load in calculator | TB-500 calculator |
| GHK-Cu | 50 mg + 2.5 mL | 20 mg/mL | 200 mcg | Load in calculator | GHK-Cu calculator |
| CJC-1295 + Ipamorelin | 5 mg + 2.5 mL | 2 mg/mL | 20 mcg | Load in calculator | CJC/Ipamorelin calculator |
| Semaglutide | 5 mg + 2 mL | 2.5 mg/mL | 25 mcg | Load in calculator | Semaglutide calculator |
| Tirzepatide | 10 mg + 2 mL | 5 mg/mL | 50 mcg | Load in calculator | Tirzepatide calculator |
| Retatrutide | 10 mg + 2 mL | 5 mg/mL | 50 mcg | Load in calculator | Retatrutide calculator |
These are example mixes for the arithmetic, not recommendations. Follow the volume on your pharmacy label when there is one — especially for prescription GLP-1 vials.
Peptide Molarity & Molecular Weight Calculator
Working in a lab rather than with a syringe? Paste a sequence in one-letter code (or enter a known molecular weight) to get the molecular weight, the moles in your vial and the molar concentration of your solution.
Uses average residue masses for the 20 standard amino acids, plus water for free termini. Non-standard residues (such as Aib or D-amino acids), lipid chains or bound metals aren’t covered — enter the MW instead.
MW = Σ residue masses + 18.02 (water)
µmol = mass (mg) ÷ MW × 1,000
mM = (mg ÷ mL) ÷ MW × 1,000
Peptide-Specific Dosage Calculators
This page is the universal tool. When your peptide has its own vial sizes, titration schedule or blend ratio, the dedicated calculators below go deeper — each one uses the same verified math.
Tirzepatide Dosage Calculator
Use it when your dose is in mg and follows the labelled 2.5 mg step-up schedule — it maps each titration step to syringe units for compounded vials.
Open calculator →Semaglutide Reconstitution Calculator
Built for weekly semaglutide doses that start in fractions of a milligram, where a small mixing error becomes a large percentage error.
Open calculator →Retatrutide Dosage Calculator
For weekly retatrutide math and dose-progression tables. Retatrutide is still in clinical trials, so this tool covers arithmetic only.
Open calculator →BPC-157 Dosage Calculator
The most-searched research peptide. Its page covers 2, 5 and 10 mg vials in mcg doses, plus the latest 2026 FDA compounding update.
Open calculator →TB-500 Dosage Calculator
TB-500 is written in mg, so draws get large. Its page flags injections over 1 mL and handles TB-500 + BPC-157 blends.
Open calculator →GHK-Cu Dosage Calculator
For large 50–200 mg copper-peptide vials: adds copper per injection, % w/v strength and a GLOW-blend breakdown.
Open calculator →CJC-1295 / Ipamorelin Calculator
Use this when both peptides share one vial — it shows how many mcg of each you get per unit, which a single-peptide calculator cannot.
Open calculator →Tesamorelin Dosage Calculator
Covers tesamorelin’s small vial volumes and daily dosing, where a 0.3 mL syringe and careful water choice matter most.
Open calculator →Which Peptides Are FDA-Approved in 2026?
A calculator can do the math for any compound, but the regulatory picture is very different from one peptide to the next. Here is where the peptides in this cluster stand as of this review.
| Peptide | US status (Oct 2026) | Dose usually written in | Dedicated tool |
|---|---|---|---|
| Tirzepatide | FDA-approved Mounjaro® / Zepbound® | mg, weekly | Tirzepatide calculator |
| Semaglutide | FDA-approved Ozempic® / Wegovy® | mg, weekly | Semaglutide calculator |
| Tesamorelin | FDA-approved Egrifta® (HIV-associated abdominal fat) | mg, daily | Tesamorelin calculator |
| Retatrutide | Investigational Not approved; Lilly plans to file in Q1 2027 | mg, weekly (trials) | Retatrutide calculator |
| BPC-157 | Not approved FDA advisory panel voted 8–6 (July 2026) to recommend it for the 503A compounding list; final FDA decision pending | mcg | BPC-157 calculator |
| TB-500 | Not approved FDA advisory panel recommended it for compounding (wound healing, July 2026); final decision pending | mg | TB-500 calculator |
| GHK-Cu | Not approved Topical sold as a cosmetic; injectable removed from FDA Category 2 in April 2026 but not on the compounding list | mg | GHK-Cu calculator |
| CJC-1295 / Ipamorelin | Not approved No FDA-approved product | mcg | CJC/Ipamorelin calculator |
Status changes fast. An advisory-committee vote is not an approval, and compounding eligibility is separate from drug approval. Check the FDA sources listed below before relying on this table.
7 Common Peptide Reconstitution Mistakes
1. Mixing up mg and mcg
A 0.25 mg dose entered as 25 mcg is ten times too small; entered as 250 mg it is a thousand times too large. Toggle the unit rather than retyping.
2. Reading U-100 numbers on a U-40 syringe
Same barrel size, different scale. Select the syringe you actually have.
3. Doses that fall between marks
12.5 units on a 2-unit-tick syringe is a guess. The optimizer finds water volumes that land on a printed line.
4. Using too little water
A 2-unit draw has a much larger percentage error than a 20-unit draw. Small volumes magnify every misreading.
5. Keeping the vial past 28 days
A bigger vial is not a bargain if half of it expires. The timeline shows exactly how many doses fall outside the window.
6. Shaking the vial
Vigorous shaking can foam and denature peptide chains. Swirl gently and let it dissolve.
7. Forgetting the blend ratio
In a two-peptide vial, every unit delivers both compounds. Use Blend mode so you know what each injection contains.
Why trust this calculator?
Every output was checked against hand-worked cases, including all 40 cells of the chart above. The code runs entirely in your browser, and the page is re-reviewed whenever FDA status changes.
Peptide Calculator FAQs
Divide the vial’s mg by the water in mL to get mg/mL, multiply by 1,000 for mcg/mL, divide your dose in mcg by that figure to get mL, then multiply by 100 for a U-100 syringe. For example, 5 mg in 2 mL is 2,500 mcg/mL, so 250 mcg is 0.1 mL, or 10 units.
It depends on the concentration. In a 5 mg vial with 2 mL of water, 250 mcg is 10 units. In a 5 mg vial with 1 mL it is 5 units, and in a 10 mg vial with 2 mL it is also 5 units.
Many people use 2 mL, which gives 2.5 mg/mL and 25 mcg per U-100 unit. The right volume is the one that puts your prescribed dose on a clear syringe mark, ideally between 10 and 50 units. Use the BAC water optimizer to compare volumes.
1 mL gives 10 mg/mL (100 mcg per unit) and 2 mL gives 5 mg/mL (50 mcg per unit). For prescription GLP-1 vials, follow the volume on your pharmacy label.
The best one does more than divide numbers. It should support U-100, U-40 and mL syringes, warn when a dose falls between marks, handle blends, and track the 28-day beyond-use window. This calculator does all of that for free, with no sign-up.
Yes. Switch to Blend mode and enter up to three peptides with their mg amounts. Your dose is set by the first peptide, and the tool shows how many mcg of every peptide each injection delivers.
No. More water makes each mL weaker, so you draw a larger volume to get the same mcg. The total peptide in the vial and the number of doses stay the same.
For a multiple-dose vial made with bacteriostatic water, USP <797> generally sets a 28-day beyond-use date after first puncture unless the manufacturer states otherwise. Keep it refrigerated and protected from light.
Sterile water has no preservative, so it is generally meant for a single use. If a vial will be entered several times, bacteriostatic water is the usual choice. Ask your pharmacist which diluent your product requires.
No. In July 2026 an FDA advisory committee voted 8–6 to recommend adding BPC-157 to the 503A bulks list for compounding, but that is a recommendation, not an approval. The FDA has not issued a final decision.
No. It only converts the dose you enter into a volume and syringe reading. Dose decisions belong to a licensed prescriber who knows your medical history.
It depends on the mix. In a 5 mg vial with 2 mL of water, 10 units on a U-100 syringe hold 250 mcg; in a 10 mg vial with 2 mL they hold 500 mcg. Use the reverse lookup in the calculator for your own vial.
Pick the smallest U-100 insulin syringe that holds your whole dose: 0.3 mL (30 units) for draws under 30 units, 0.5 mL (50 units) up to 50, and 1 mL (100 units) above that. Smaller syringes have finer marks, so small doses are easier to measure accurately.
IU-to-mg conversions are specific to each substance and can’t be applied across peptides. For somatropin (human growth hormone), the accepted conversion is about 3 IU per mg. Check the product label for any IU-dosed medicine.
Divide the concentration in mg/mL by the molecular weight in g/mol and multiply by 1,000 to get millimolar (mM). For example, BPC-157 at 2.5 mg/mL with a molecular weight of about 1,419.5 g/mol is about 1.76 mM. The lab mode on this page does this for any sequence.
Nothing is sent to a server. Calculations run in your browser, and your last vial is remembered only on your own device so you don’t have to re-enter it. Press Reset to clear it.
Manzoor Ahmad, Pharm-D
Licensed Pharmacist · Founder, DexoCalc
Manzoor is a licensed pharmacist with more than nine years of experience writing about supplements and medication safety, and 13+ years building web tools. He runs a community pharmacy, where checking dilution and dose arithmetic is daily work. He wrote and tested the formulas on this page against hand-worked pharmacy calculations and reviews it whenever FDA guidance changes.
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Sources
- U.S. Pharmacopeia. General Chapter <797> Pharmaceutical Compounding — Sterile Preparations (beyond-use dating for multiple-dose containers).
- U.S. FDA. Bulk Drug Substances Used in Compounding (503A categories and bulks list).
- Regulatory Affairs Professionals Society. FDA advisory committee backs two controversial peptides, July 23, 2026.
- AJMC. 5 things to know about the FDA’s peptide reversal, August 21, 2026.
- Drugs.com. Retatrutide FDA Approval Status, updated July 24, 2026.
- NIH DailyMed. Bacteriostatic Water for Injection — product labelling.
Disclaimer: This peptide calculator is an educational arithmetic tool. It does not diagnose, treat or recommend any dose, product or protocol. Several peptides referenced here are not FDA-approved for human use. Always follow the directions of a licensed prescriber and pharmacist, and verify every syringe reading before injecting. DexoCalc is not affiliated with any drug manufacturer; brand names belong to their owners.