Key takeaways
- Units = dose ÷ concentration × 100 on a U-100 syringe. 250 mcg at 2.5 mg/mL is 10 units.
- Weekly total = dose × doses per week. Every other day averages 3.5 doses a week, not 3.
- A dosage chart converts amounts; it does not prescribe them. It is only valid for the concentration printed on it.
- Vial supply = whole doses × days between doses. Compare it with the vial’s beyond-use date.
- The FDA has reported people drawing 5 to 20 times their intended dose after mix-ups between mg, mL and units.
How to use the peptide dosage calculator
The calculator takes the same inputs as a reconstitution calculator, then adds your schedule. That lets it show what one dose measures and what a week of doses and a whole vial add up to.
- Set the concentration. Choose From my vial if you mixed the vial yourself, and enter the mg on the label plus the mL of water you added. Choose I know it if the vial already states a concentration, such as 2.5 mg/mL, and enter the total liquid in the vial.
- Enter the dose per injection in mcg or mg, exactly as your prescription writes it. The tool flags numbers that look like an mg and mcg mix-up.
- Choose how often. Pick a preset or Custom and type doses per week. Twice a week is 2; every third day is about 2.33.
- Pick the syringe you actually use. Tick U-40 only if the barrel says U-40.
- Read the results. The big number is where to draw. Below it are the weekly totals, doses per vial and how long one vial lasts. Open Show the math to check each step.
- Print the chart if you want a paper reference. Set a start and step, or press Centre on my dose.
Dosage chart vs dosing protocol: what’s the difference?
People search for a “peptide dosage chart” expecting two very different things. It helps to separate them, because mixing them up is how people end up following numbers that were never meant for them.
| Dosage (conversion) chart | Dosing protocol | |
|---|---|---|
| Answers | How do I measure this amount? | What amount, how often and for how long? |
| Depends on | Concentration and syringe type | The drug, the patient and the indication |
| Comes from | Arithmetic, like this calculator | A prescriber, a drug label or a trial protocol |
| Changes when | You mix a vial with a different volume | Your prescriber changes the plan |
A protocol is a clinical decision. For approved drugs it is written in the label. The Zepbound (tirzepatide) label, for example, starts at 2.5 mg injected once weekly for 4 weeks. The Humatrope (somatropin) label writes the pediatric dose per week and says to divide it into equal doses given 6 or 7 days a week. Our chart can tell you what 2.5 mg measures at your concentration. It cannot tell you whether 2.5 mg is right.
Many research peptides have no approved label at all, so there is no approved protocol. Dose tables shared online for those products are not medical guidance, and this site does not reproduce them.
The peptide dosage formulas
Four short formulas cover everything the calculator shows. The first three turn one dose into a syringe reading. The fourth scales it to a week.
One U-100 unit is 0.01 mL, whichever barrel size you use.
Every other day counts as 3.5 doses per week on average.
| Symbol | Meaning | Unit | Where to find it |
|---|---|---|---|
| Vial | Total peptide in the vial | mg | Vial or box label |
| Water | Diluent added | mL | What you injected into the vial |
| C | Concentration | mcg/mL or mg/mL | Calculated, or printed on pre-mixed vials |
| Dose | Amount per injection | mcg or mg | Your prescription |
| V | Volume to draw | mL | Calculated |
| Doses per week | Frequency as a number | per week | Your prescription (daily = 7) |
Frequency and weekly totals
Frequency does not change the units per dose. It changes how fast the vial empties and how much you inject in a week. Converting the schedule to doses per week makes every frequency comparable.
The table below uses the same example, a 5 mg vial with 2 mL of water and a 250 mcg dose, and shows how the week and the vial change with frequency. The last column counts the doses that fall within 28 days of mixing, a common default beyond-use window for punctured multiple-dose vials.
| Frequency | Doses / week | Weekly total | Weekly volume | Weekly units | Vial lasts | Doses used by day 28 |
|---|---|---|---|---|---|---|
| Daily | 7 | 1.75 mg | 0.7 mL | 70 | 20 days | 20 of 20 |
| Every other day | 3.5 | 0.875 mg | 0.35 mL | 35 | 40 days | 14 of 20 |
| 5× per week | 5 | 1.25 mg | 0.5 mL | 50 | 28 days | 20 of 20 |
| 3× per week | 3 | 0.75 mg | 0.3 mL | 30 | 46.7 days | 12 of 20 |
| 2× per week | 2 | 0.5 mg | 0.2 mL | 20 | 70 days | 8 of 20 |
| Once weekly | 1 | 0.25 mg | 0.1 mL | 10 | 140 days | 4 of 20 |
Vial lasts = 20 whole doses × days between doses. It ignores the beyond-use date; the last column applies it.
The weekly row is the one that surprises people. The vial holds 20 doses, but only 4 fall within 28 days of mixing. With infrequent dosing, the beyond-use date, not the vial size, decides how much of the vial you can use.
How to read units on an insulin syringe
The “units” on an insulin syringe are volume marks. On a U-100 syringe, 1 unit is 0.01 mL whatever drug is inside. They are not the international units (IU) used to label some hormones, which measure biological activity. If your product is labelled in IU, convert with the HGH IU to mg calculator first.
- 0.3 mL syringes hold 30 units and are often marked every half unit. They suit doses under about 30 units.
- 0.5 mL syringes hold 50 units, usually marked every unit.
- 1 mL syringes hold 100 units, usually marked every 2 units, so odd numbers fall between lines.
Count the lines between two numbered marks before you draw. If ten lines sit between 0 and 10, each line is 1 unit; if five, each is 2 units. Read the dose at the edge of the plunger’s rubber stopper closest to the needle, with the syringe at eye level. When a dose lands between marks, the calculator’s warning shows the nearest mark and what it delivers. You can also change the water volume so the dose lands on a line; the BAC water calculator works that backwards.
Peptide dosage chart: units by dose and concentration
This reference chart lists U-100 units for common amounts at five concentrations. Find the concentration printed on your vial or worked out by the calculator, then read down to the amount on your prescription. It is a conversion table, not a list of suggested doses.
| Amount | 1 mg/mL | 2 mg/mL | 2.5 mg/mL | 5 mg/mL | 10 mg/mL |
|---|---|---|---|---|---|
| mcg per unit | 10 | 20 | 25 | 50 | 100 |
| 100 mcg | 10 | 5 | 4 | 2 | 1 |
| 200 mcg | 20 | 10 | 8 | 4 | 2 |
| 250 mcg | 25 | 12.5 | 10 | 5 | 2.5 |
| 300 mcg | 30 | 15 | 12 | 6 | 3 |
| 500 mcg | 50 | 25 | 20 | 10 | 5 |
| 750 mcg | 75 | 37.5 | 30 | 15 | 7.5 |
| 1 mg | 100 | 50 | 40 | 20 | 10 |
| 2 mg | — | 100 | 80 | 40 | 20 |
| 2.5 mg | — | — | 100 | 50 | 25 |
| 5 mg | — | — | — | 100 | 50 |
A dash means the amount is over 100 units (1 mL) at that concentration. To read units back into mcg, use the reverse peptide calculator.
Worked examples
Example 1: 5 mg vial, 2 mL water, 250 mcg daily
Concentration is 5,000 ÷ 2 = 2,500 mcg/mL. Each dose is 250 ÷ 2,500 = 0.1 mL, or 10 units. Seven doses a week add up to 1,750 mcg (1.75 mg), 0.7 mL or 70 units. The vial holds 20 doses, so it lasts 20 days.
Example 2: 10 mg vial, 2 mL water, 500 mcg three times a week
Concentration is 5 mg/mL, so each unit holds 50 mcg and 500 mcg is 10 units (0.1 mL). The weekly total is 1.5 mg, or 30 units. The vial holds 20 doses and would last about 47 days. Only 12 doses fall inside a 28-day beyond-use window, so 8 doses (4 mg) would be left over.
Example 3: pre-mixed vial labelled 5 mg/mL, 2 mL, 2.5 mg once weekly
Choose I know it and enter 5 mg/mL and 2 mL. The vial holds 10 mg. Each 2.5 mg dose is 2.5 ÷ 5 = 0.5 mL, or 50 units, which half-fills a 1 mL syringe and completely fills a 0.5 mL one. The vial holds 4 weekly doses and lasts 4 weeks.
Example 4: a prescription written as a weekly amount
Some prescriptions state a weekly total and the number of injections. If yours says 1.4 mg per week in 7 equal injections, each injection is 1,400 ÷ 7 = 200 mcg. At 2.5 mg/mL that is 8 units. Enter the per-injection amount in the calculator, never the weekly total. The mcg to mg converter helps if the two are written in different units.
How long will a vial last on your schedule?
Doses per vial is the vial’s peptide divided by the dose, rounded down to whole doses. A leftover smaller than a full dose cannot be drawn as a dose. Multiply the whole doses by the days between doses (7 ÷ doses per week) to get the days one vial covers.
Example 2: floor(10,000 ÷ 500) = 20 doses × 7 ÷ 3 = 46.7 days.
Two things shorten that number in real life. First, a little liquid is lost with every injection to the needle hub and to air bubbles you expel. Second, the vial has a beyond-use date. The CDC says an opened multi-dose vial should be dated and discarded within 28 days unless the manufacturer states a different date. The doses per vial and vial expiry calculator adds both, and gives you the exact date the vial runs out or expires.
Printing and using your dose-to-units chart
The chart under the calculator lists ten amounts around your dose, each with its mcg or mg equivalent, volume and units. Press Print chart and only the chart is printed, with the concentration line at the top and blank lines for the mix date and a second person’s check.
- One chart per concentration. Write the concentration and the date mixed on it. Throw it away when you mix with a different volume.
- Keep it with the vial, not with a different product. A chart for 2.5 mg/mL gives wrong answers for a 5 mg/mL vial.
- Pick a readable step. If your prescription changes in 0.5 mg steps, set the step to 0.5 mg so each row is an amount you might actually see.
- Check the highlighted row against your prescription before you draw. The chart does not know what your prescriber intended.
Common peptide dosing-math mistakes
In 2024 the FDA reported that people using compounded semaglutide had, in most of the cases it reviewed, drawn more than the intended dose, sometimes 5 to 20 times more. The agency named confusion between millilitres, milligrams and units, and syringes much larger than the dose, as likely contributors. The same errors apply to any peptide.
- mg for mcg. 250 mg is 1,000 times 250 mcg. The calculator flags mg doses of 50 or more.
- mL read as units. 0.1 mL is 10 units on U-100, not 0.1 units.
- A U-40 syringe with U-100 numbers. Every unit holds 2.5 times more liquid.
- Treating every other day as 3 per week. It averages 3.5, so a vial runs out sooner than the 3-per-week math suggests.
- Injecting a weekly total as a single dose when the prescription splits it across the week.
- Using a chart made for another concentration, including an old chart after re-mixing with a different volume.
- A dose larger than the syringe. If it needs more than one fill, use a larger syringe or check the concentration.
Key terms
- Dose
- The amount of peptide in one injection, in mcg or mg.
- Dosing protocol
- A clinical plan for dose, frequency and duration, set by a prescriber or a drug label.
- Dosage chart
- Here, a conversion chart showing the volume and units for a list of amounts at one concentration.
- Concentration
- Peptide per volume of solution, in mg/mL or mcg/mL.
- U-100 unit
- A syringe graduation equal to 0.01 mL.
- Doses per week
- Frequency written as a number: daily is 7, every other day averages 3.5.
- Weekly total
- Dose multiplied by doses per week.
- Beyond-use date (BUD)
- The date after which an opened or compounded preparation should not be used.
Frequently asked questions
How do I calculate a peptide dose in units?
Divide the dose by the concentration to get millilitres, then multiply by 100 for a U-100 syringe. At 2.5 mg/mL (5 mg in 2 mL), 250 mcg is 250 ÷ 2,500 = 0.1 mL, which is 10 units. The mg to units calculator does the same conversion without a vial.
How many units is 250 mcg of a peptide?
It depends on the concentration. At 1 mg/mL it is 25 units, at 2.5 mg/mL it is 10 units and at 5 mg/mL it is 5 units on a U-100 syringe. That is why a units number is meaningless without the concentration next to it.
What is a peptide dosage chart?
On this site it is a conversion chart: a list of amounts with the volume and syringe units each one measures at one concentration. It answers “how do I measure this amount?”, not “what amount should I take?”. The dose comes from your prescription or product label.
How do I work out my weekly peptide total?
Multiply the dose by the number of doses per week. 250 mcg daily is 250 × 7 = 1,750 mcg (1.75 mg) per week. 250 mcg three times a week is 750 mcg. Do the same with units: 10 units daily is 70 units per week. The mcg to mg converter helps when the totals mix units.
How many doses per week is every other day?
An average of 3.5. Every-other-day dosing alternates between 4 doses in one week and 3 in the next, because a week has an odd number of days. Use 3.5 for weekly totals and vial planning; the calculator does this automatically.
How long will a 5 mg peptide vial last?
At 250 mcg a dose it holds 20 doses. Daily, that is 20 days. Three times a week, it is about 47 days, which is longer than the common 28-day beyond-use date for a punctured vial. The doses per vial calculator shows how many doses would expire.
Is 0.1 mL the same as 10 units?
Yes, on a U-100 insulin syringe. U-100 means 100 units per mL, so each unit is 0.01 mL and 0.1 mL is 10 units. On a U-40 syringe 0.1 mL is only 4 units, which is why the calculator warns you when U-40 is selected.
Can I use this calculator for semaglutide or tirzepatide?
Yes, the arithmetic is the same for any reconstituted or pre-mixed injectable. The semaglutide and tirzepatide calculators add presets and the labelled dose schedules. Pre-mixed compounded vials state mg/mL on the label, so choose I know it and use the concentration printed on your own vial.
Does this calculator tell me what dose to take?
No. It converts the dose you enter into volume, units and weekly totals. It does not recommend a dose, a frequency or a duration. Those come from your prescriber and your product label. If you are unsure whether an amount is right for you, ask your prescriber or pharmacist before you draw it.
How do I print a peptide dose chart?
Set your concentration and dose, adjust the chart start and step if you want a different range, then press Print chart. Only the chart, its concentration line and a space to write the mix date are printed. Print a new chart whenever the concentration changes.
Sources
We check every formula and figure on this page against primary sources. See our editorial policy for how we review content.
Reviewed by the PeptideConvert Editorial Team
Last reviewed . PeptideConvert tools do arithmetic only. They do not recommend a dose, and nothing on this site is medical advice. Always follow the label and your prescriber. Read the full medical disclaimer.