Peptide dosage charts: the math they omit

A chart says 20 units. The vial contains 5 mg. The page does not say how much liquid was added, which syringe scale it assumes, or whether 20 units means 1 mg or 2 mg. That is not a minor omission. It is the entire calculation.

Most search results for a peptide dosage chart have the same structural problem: they present a number that looks portable but is tied to an unstated concentration. Others lift animal-study milligram-per-kilogram figures and place them beside human-facing instructions. Pages published by businesses selling the compound also give the reader a reason to inspect the claims rather than accept the table.

This article does not recommend a compound, amount, frequency, or duration. A dosing decision belongs to a licensed prescriber. It does show how to audit a chart and rebuild the arithmetic from the vial actually in front of you.

The unit number is not the dose

An insulin syringe unit is a volume marking. It is not a milligram, microgram, or biological effect.

On a standard U-100 syringe, 100 units equals 1 mL. Therefore:

• 1 unit = 0.01 mL
• 10 units = 0.10 mL
• 20 units = 0.20 mL
• 50 units = 0.50 mL

That conversion says nothing about the peptide amount until concentration enters the equation. A U-40 syringe uses a different scale: 40 units equals 1 mL. Twenty units on U-40 is 0.50 mL, not 0.20 mL. The syringe barrel must identify its scale; assuming U-100 because a chart uses the word units is a basic failure.

The governing equations are short:

concentration = amount in vial ÷ final liquid volume
volume needed = desired amount ÷ concentration
U-100 syringe units = volume in mL × 100
U-40 syringe units = volume in mL × 40

The units cancel if the equation is written correctly. For example, dividing 5,000 mcg by 2,500 mcg/mL leaves 2 mL, because mcg ÷ (mcg/mL) = mL. This dimensional check catches a surprisingly common mistake: multiplying the target mass by concentration instead of dividing by it.

For a complete walkthrough, see How to reconstitute peptides: the arithmetic, step by step. The arithmetic is not difficult. Keeping the inputs attached to the result is the difficult part.

Defect one: charts publish units without concentration

Consider a 10 mg vial. The chart says 20 units. That statement is incomplete because the same vial can produce different concentrations after different volumes of diluent are added.

Worked example: the twofold error

Mixture A adds 2 mL:

10 mg ÷ 2 mL = 5 mg/mL
5 mg/mL = 5,000 mcg/mL
20 U on U-100 = 0.20 mL
0.20 mL × 5,000 mcg/mL = 1,000 mcg = 1 mg

Mixture B adds 1 mL:

10 mg ÷ 1 mL = 10 mg/mL
10 mg/mL = 10,000 mcg/mL
20 U on U-100 = 0.20 mL
0.20 mL × 10,000 mcg/mL = 2,000 mcg = 2 mg

The printed unit number is identical. The amount delivered is different by a factor of two. A reader following the chart cannot detect the error because the chart omitted the one variable that controls it.

The reverse problem is just as common. Someone may know the desired amount in micrograms but copy a unit number from a different vial. If the concentration doubles, the required volume halves. The syringe does not know which vial is attached to it.

A chart also fails if it leaves the final volume ambiguous. “Add 2 mL” may refer to the volume drawn into the syringe, not necessarily the final volume after powder displacement. For ordinary small-vial arithmetic, worksheets may treat the added volume as the working volume. That assumption should be recorded, not hidden. If a manufacturer supplies a validated final concentration, use that stated concentration rather than pretending every vial behaves identically.

A second concentration error appears when a chart silently switches between mg/mL and mcg/mL. Since 1 mg equals 1,000 mcg, writing 2.5 mg/mL as 2.5 mcg/mL creates a thousandfold numerical error. The safest worksheet displays both units on the same line and labels the conversion explicitly.

The Peptide reconstitution calculator is useful for making these dependencies visible. It should be treated as a calculator, not as a source of a medical dose.

Defect two: animal mg/kg becomes a fake human dose

A number expressed as milligrams per kilogram looks transferable because the unit is familiar. It is not a universal exchange rate between species.

Suppose an animal paper reports 1 mg/kg in a rat experiment. Multiplying by a 70 kg adult gives 70 mg. That is simple multiplication and poor translation. It ignores species differences in metabolism, absorption, distribution, receptor activity, clearance, and toxicity.

A commonly used preliminary body-surface-area conversion uses Km factors of approximately 6 for rats and 37 for adult humans. Applying that method to the illustrative animal number gives:

animal dose = 1 mg/kg
rough human-equivalent dose = 1 × (6 ÷ 37)
                         = 0.162 mg/kg
for 70 kg = 11.35 mg

The naive weight multiplication produced 70 mg. The body-surface-area estimate produced about 11.4 mg, a difference of more than sixfold. Neither number is a human dosing instruction. The second is only a scaling exercise, and it still does not establish safety, an appropriate route, a schedule, or a clinically meaningful exposure.

Human-equivalent calculations can be useful in research planning, but they are not a shortcut around human pharmacology or clinical review. A peptide dosage chart by weight that places an animal mg/kg value beside a human weight invites precisely the wrong inference: that multiplying body weight is enough.

There is a second trap. Some animal experiments use exposure levels selected to test a mechanism, not to imitate a therapeutic human concentration. A result may show that a receptor pathway responds at a particular experimental exposure. It does not show that a person should reproduce the number with a syringe.

Route also matters. A mass administered by injection cannot be assumed to produce the same exposure as the same mass delivered by another route. Absorption may be incomplete, delayed, or altered by formulation. Even within injection-based research, pharmacokinetic results depend on the preparation and study design. A weight-based table that omits route and formulation is missing variables that arithmetic cannot supply.

Defect three: the seller is also the author

A vendor-published chart has a built-in conflict: the page benefits when the reader feels confident enough to buy and use the product. That does not prove every number is false. It does mean the chart deserves the same scrutiny as an advertisement, especially if it omits uncertainty, product testing, contraindications, or the assumptions behind its units.

The missing information is often more revealing than the visible table. Look for the vial strength, diluent volume, concentration, syringe scale, measurement resolution, stability basis, lot-specific testing, and distinction between animal data and human evidence. A table that cannot answer those questions is not a reference; it is a number generator.

Most research peptides are not approved by the FDA or EMA for human use. Material sold as “research use only” is not manufactured to pharmaceutical standards, and purity, sterility, identity, and actual content are not guaranteed. A certificate of analysis, even where one exists, does not automatically establish sterility or make a research product equivalent to an approved medicine.

Some molecules have approved medicines in particular formulations and indications. That fact does not transfer automatically to a different concentration, salt, device, compounding process, or research-vial source. The label and formulation are part of the product, not clerical details.

“Research use only” is also not a concentration statement. It does not tell a reader whether the vial contains the labeled mass, whether the powder is sterile, or whether the material remains stable after preparation. Those are separate questions requiring qualified product information and appropriate testing.

Build your own reference from the actual vial

A defensible reference starts with a record, not a dose table. Write down the vial strength exactly as labeled, the amount of diluent added, the working final volume, the syringe scale, and the date of preparation. If any input is unknown, mark it unknown. Do not fill the gap with a popular chart.

Step 1: normalize the amount

Use one mass unit throughout the calculation. Convert milligrams to micrograms before dividing if the target is written in micrograms:

1 mg = 1,000 mcg
5 mg = 5,000 mcg
10 mg = 10,000 mcg

Do not confuse mg with mL. Milligrams describe mass. Milliliters describe liquid volume. They become related only through concentration.

Do not round at the beginning of the calculation. Carry at least one extra decimal place through the concentration and volume steps, then compare the result with the actual syringe graduations. Early rounding can turn a small calculated volume into a different visible marking, particularly when the vial contains 5 mg or more and the intended volume is below 0.1 mL.

Step 2: calculate concentration

If a vial contains 5 mg and the working volume is 2 mL:

5 mg ÷ 2 mL = 2.5 mg/mL
2.5 mg/mL × 1,000 = 2,500 mcg/mL

This is the key line that most generic peptide dosing charts omit. Preserve it beside every unit conversion.

For questions about selecting and measuring diluent, see How much bacteriostatic water to add to a peptide vial and the Bacteriostatic water calculator. Those resources address volume arithmetic, not whether a specific product is suitable for human use.

Step 3: convert an amount to volume

If the known amount is 250 mcg and the concentration is 2,500 mcg/mL:

250 mcg ÷ 2,500 mcg/mL = 0.10 mL

For a U-100 syringe:

0.10 mL × 100 = 10 units

For a U-40 syringe, the same 0.10 mL would be:

0.10 mL × 40 = 4 units

The mass did not change. The unit label changed because the syringe scale changed. The mcg to units converter and Insulin syringe unit visualizer can help check this last step, particularly on a small barrel where graduations are easy to misread.

Step 4: check the physical measurement

A mathematical result can be too small to measure reliably on a particular syringe. A 0.01 mL graduation does not make every value between marks exact. Dead space, plunger position, bubbles, eye level, and handling technique add practical variation.

Record the syringe capacity and graduation. A 0.3 mL U-100 syringe generally reaches 30 units, a 0.5 mL syringe 50 units, and a 1 mL syringe 100 units. Those capacities describe common formats, not permission to use a particular device or a guarantee that every manufacturer prints the same markings.

A syringe marked in units is not interchangeable with one marked only in mL unless its scale is known. The barrel may also use half-unit or two-unit graduations, so a calculated result such as 7.3 units may not correspond to a distinct line. That is a measurement limitation, not a reason to invent a rounding rule. A licensed clinician or pharmacist must determine how a prescribed amount should be measured with the available device.

How to read an insulin syringe when the vial is not insulin explains why the word unit on the barrel refers to volume calibration. The Insulin syringe unit visualizer provides a second visual check, but the label on the actual syringe remains authoritative.

Step 5: store the calculation with the vial

A useful reference line looks like this:

Vial: 5 mg
Working volume: 2.00 mL
Concentration: 2.50 mg/mL = 2,500 mcg/mL
Syringe: U-100
Conversion: 10 U = 0.10 mL = 250 mcg
Prepared: [date]

The final line in that example is an arithmetic conversion, not a recommendation to use 250 mcg. The amount that belongs in a person’s treatment plan is a separate clinical decision.

Also record the vial identifier or lot number when it is available, the labeled solvent, the storage condition specified for that material, and whether the container has been punctured. These fields do not prove quality or sterility, but they make it possible to distinguish one preparation from another and to investigate a discrepancy instead of relying on memory.

Reconstitution also creates a storage question that charts rarely address. Light, heat, agitation, container closure, solvent composition, repeated puncture, and time can affect stability or contamination risk. There is no honest universal “good for” period for every peptide and every preparation. See Storing peptides after reconstitution: what actually degrades them for the variables that must be checked.

Error checks before trusting a conversion

A calculation can be internally consistent and still be based on a wrong input. Use these checks before treating a chart as a reference:

1. Confirm the vial label uses mg, mcg, or another mass unit. Do not enter a number without its unit.
2. Confirm that the volume is in mL, not syringe units. Convert units to mL before calculating concentration.
3. Confirm whether the syringe is U-100, U-40, or marked only in mL.
4. Calculate the same result in both mg and mcg. The answers should differ by exactly 1,000, not by an unexplained factor.
5. Reverse the equation. If 0.10 mL is calculated for 250 mcg, then 0.10 mL multiplied by 2,500 mcg/mL must return 250 mcg.
6. Compare the calculated volume with the syringe’s capacity and graduation. A result outside the barrel’s range is not usable as written.
7. Keep the vial strength and preparation volume beside the final unit number. A bare “10 U” is not a reproducible record.

These checks address arithmetic and measurement clarity. They do not establish the identity, sterility, stability, potency, or suitability of the material.

A compact reference table

Use this table to audit a number, not to select one. It assumes the vial amount and working volume are known and that the syringe is correctly identified.

Why a generic peptide dosing chart cannot be universal

The phrase peptide dosing chart suggests that one table can cover semaglutide, tirzepatide, BPC-157, retatrutide, and unrelated molecules with the same logic. Only the unit arithmetic is generic. Pharmacology is not.

Molecules differ in receptor targets, half-life, absorption, degradation, route, formulation, and human evidence. Even within one molecule, a concentration can change the unit number without changing the prescribed mass. A chart that mixes names, milligrams, and syringe units without separating those layers encourages a false sense of comparability.

This is especially visible in GLP-1-related searches. Two charts may show different units for what appears to be the same amount because one assumes a different vial strength or reconstitution volume. Semaglutide units: why the same dose is a different number of units and Tirzepatide dosage charts in units, and why they disagree focus on that concentration problem rather than pretending the unit number is intrinsic to the molecule.

Titration adds another layer. A schedule is not merely a dosage chart with dates added; it reflects tolerability, response, labeling, and clinical monitoring. A GLP-1 titration schedule planner can organize a schedule supplied by a clinician. It cannot decide the starting amount or escalation plan.

Dosyne is designed around the same separation: record the vial and diluent inputs, show the conversion, and keep the resulting dose and vial history tied to that preparation rather than to a floating internet chart. A dose log is useful because the vial can change while the compound name stays the same.

For readers who want a phone-based record of calculations, injections, site rotation, and reminders, search for “Dosyne Peptide Calc & Tracker” in the App Store or Google Play. The arithmetic still depends on the values entered.

What to reject in a peptide dosage cheat sheet

Reject any reference that gives units without stating U-100 or U-40. Reject any table that gives units without vial strength and diluent volume. Reject an animal mg/kg figure presented as a human amount, and reject a page that treats “research use only” as a quality assurance statement.

Treat a PDF as a snapshot, not a source of authority. A saved file may preserve a unit number while hiding the product lot, formulation, date, or assumptions that made the number meaningful. If you cannot reconstruct its calculation from the page, it cannot safely serve as your reference.

A good personal worksheet has four sections: product facts, concentration math, syringe conversion, and preparation record. It also has a blank field for unknowns. The blank field is more honest than a guessed volume.

Add a fifth field for the source of the amount being converted. That field should identify the prescription or clinician-provided instruction, not a search result or an animal paper. Keeping the source separate from the arithmetic prevents a calculator from appearing to validate an amount that it merely converted.

Bottom line

Most peptide dosage charts are unusable as written because they confuse volume units with peptide mass, convert animal experiments into human-looking numbers, or present sales material as neutral guidance. Do not repair those defects by finding a better chart.

Build the reference from the actual vial: identify the mass, record the working volume, calculate mg/mL or mcg/mL, identify the syringe scale, reverse-check every conversion, and attach the result to the vial lot and preparation date. The arithmetic can be exact. The product quality, sterility, stability, actual content, and human suitability may still be unknown, and only a licensed prescriber can determine whether a treatment amount belongs in a person’s care.