PeptideCalculations
Guide

How to Read a Peptide Dosage Chart (and Turn It Into Syringe Units)

What a dose range means, the three basis types (label, trial, commonly reported), weekly vs daily totals, and two worked conversions from a chart row to units.

By the Peptide Calculations editors · Updated 2026-10-19

A dosage chart compresses a lot into one row: a range, a frequency, a route, and a claim about where the numbers came from. This guide reads a row the way the editors who build them do, then walks two rows from this site’s tables all the way to a number on a syringe. The two examples are BPC-157 at 250 mcg and semaglutide at 0.25 mg, both from a 5 mg vial mixed with 2 mL, and both land on 10 units for reasons worth understanding. The chart is a reference, not a prescription; talk to a clinician and start at the bottom of any range.

What a range means

A row that says “250 to 500 mcg” is not saying 375 is ideal. It is saying the low end is where reported use begins and the high end is where it stops.

Basis. This is the column most charts leave out and this site always includes. Every dose range has one of three sources:

Basis What it is Example
FDA label A dose on an approved product’s prescribing information, tested in trials of thousands and reviewed by regulators Wegovy: 0.25 mg weekly for weeks 1 to 4, up to 2.4 mg maintenance
Trial A dose arm from a published human study, usually small, often not approved Retatrutide: 1, 4, 8 or 12 mg weekly for 48 weeks in Jastreboff 2023 (NEJM)
Commonly reported A range repeated across community write-ups, with no human trial behind it BPC-157: 200 to 500 mcg daily; a 2025 systematic review found no human RCT

A label range is the only one with a built-in schedule, a maximum, a missed-dose rule and a side-effect table. A trial range tells you what participants received under monitoring, often with escalation that the paper does not fully print. A commonly reported range is anecdote with a lot of repetition, and the right way to read it is “this is what people say they do,” not “this is what works.”

Start low. Every label escalates. The Wegovy label holds 0.25 mg for four weeks before moving; the Zepbound label calls 2.5 mg an initiation dose and does not allow steps faster than every four weeks. The retatrutide trial found GI side effects clustered during escalation and were reduced by a 2 mg rather than 4 mg start. If regulators and trialists start at the bottom with the drugs that have the most data, the bottom is where a commonly reported range starts too.

Frequency and timing. The range is per injection. The row’s frequency column says how often: once weekly for the GLP-1 class, once or twice daily for BPC-157, daily at bedtime for most GH secretagogue write-ups.

Weekly versus daily totals

The single most expensive misreading is treating a weekly dose like a daily one or the reverse.

Semaglutide is once weekly. The 0.25 mg on the Wegovy label is one injection, once, per seven days. Drawing 0.25 mg every day would be seven times the label’s starting dose and more than the 2.4 mg maintenance dose in a week. BPC-157 is listed daily in community protocols, so 250 mcg is per day, and a weekly total is 1,750 mcg.

When a chart gives a weekly total for a daily peptide, divide by the number of injection days before converting. When it gives a per-injection amount for a twice-daily peptide, the day’s total is double. Write the per-injection figure down before touching the calculator, because that is the only number the syringe cares about.

Turning a row into units

The concentration of a reconstituted vial is the mass on the label divided by the water added, converted to mcg so it matches the dose:

concentration (mcg/mL) = vial mg × 1,000 ÷ water mL

Then the draw:

units = dose mcg ÷ concentration (mcg/mL) × 100

The ÷ gives mL. The × 100 converts mL to U-100 insulin syringe units, where 100 units is 1 mL and one unit is 0.01 mL.

Example 1: BPC-157, 250 mcg, from 5 mg + 2 mL. Concentration = 5 × 1,000 ÷ 2 = 2,500 mcg/mL. Draw = 250 ÷ 2,500 = 0.1 mL. Units = 0.1 × 100 = 10 units. The vial holds 5,000 ÷ 250 = 20 doses, which at once daily is 20 days, inside the 28-day window for a vial mixed with bacteriostatic water. On a 0.3 mL syringe, 10 units is a third of the barrel and easy to read.

Example 2: semaglutide, 0.25 mg, from 5 mg + 2 mL. First convert the dose: 0.25 mg = 250 mcg. Concentration is the same 2,500 mcg/mL. Draw = 250 ÷ 2,500 = 0.1 mL = 10 units. The vial holds 20 doses, but at once weekly that is 20 weeks, far past 28 days, so most of the vial is wasted at this step. And the label moves to 0.5 mg (20 units) at week five, 1 mg (40 units) at week nine, 1.7 mg (68 units) at week thirteen and 2.4 mg (96 units) at week seventeen, by which point a 5 mg vial is two doses.

The two examples give the same 10 units because 250 mcg is 250 mcg whether the chart wrote it as “250 mcg” or “0.25 mg.” The peptide does not change the arithmetic; the mix does. Change the water to 1 mL and both become 5 units. Change the vial to 10 mg at 2 mL and both become 5 units. Run the calculator again every time either number changes, and write the concentration on the vial so the next draw starts from the right one.

The mistakes that turn 250 mcg into 2.5 mg

Every one of these is a factor of ten or a thousand, and every one produces an answer that looks wrong on the syringe if you check.

Reading 0.25 as 2.5. A dropped decimal. 2.5 mg of BPC-157 at 2,500 mcg/mL is 1 mL, a full 100 units, half the vial in one draw for a peptide whose commonly reported ceiling is 500 mcg. Ten times the chart.

Typing mg into a mcg field. 250 entered as mg is 250,000 mcg. At 2,500 mcg/mL that is 100 mL, fifty vials. A result bigger than the vial is impossible and means a unit is wrong.

Dividing mcg by mg/mL. 250 ÷ 2.5 = 100, which reads as 100 mL or, if you then multiply by 100, as 10,000 units. Convert the concentration to mcg/mL before any mcg dose touches it; the mcg vs mg guide covers this one in detail.

Forgetting the water. A 5 mg vial is not 5 mg/mL until exactly 1 mL goes in. With 2 mL it is 2.5 mg/mL; with 3 mL it is 1.67 mg/mL. A chart that lists units without stating the mix is assuming a mix you may not have used.

Reading 2-unit markings as 1-unit. On a 1 mL insulin syringe each line is 2 units. Counting lines to “10” draws 20 units. Use a 0.3 or 0.5 mL syringe with 1-unit lines for small draws, as the syringe units guide explains.

Weekly as daily. Covered above; it does not show on the syringe, because a 10-unit draw looks right every day. Check the frequency column, not just the dose.

The checks that catch all six take ten seconds: the answer should be between 1 unit and the syringe barrel, well under the vial volume, and the same frequency the chart row states. If it fails any of those, the number is wrong, not the chart.

Sources

Questions

What does the range on a peptide dosage chart mean?

The low end is where reported use starts and the high end is where it stops, not a target. On this site each range carries a basis: FDA label, published trial, or commonly reported. A commonly reported range is anecdote, and the chart says so.

How do I convert a dosage chart into syringe units?

Units = dose in mcg divided by concentration in mcg/mL, times 100. Concentration is vial mg times 1,000 divided by water mL. For 5 mg in 2 mL that is 2,500 mcg/mL, so 250 mcg is 0.1 mL, which is 10 units.

Is a weekly dose the same as a daily dose times seven?

No. A once-weekly peptide like semaglutide is one injection of the listed amount per week. A daily peptide like BPC-157 lists the amount per injection per day. Multiplying a weekly figure into daily draws, or the reverse, is the fastest way to be off by seven.

Why does my calculator say 100 units when the chart says 250 mcg?

A unit mismatch. 250 entered as mg instead of mcg is a thousand times too much, and 2.5 mg of BPC-157 at 2,500 mcg/mL would be 1 mL, a full syringe. Any answer near a full barrel for a sub-milligram dose means a unit was typed wrong.

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