How many mcg are in a mg?

Exactly 1,000, by definition rather than by measurement — NIST lists the SI prefix milli as 10⁻³ and micro as 10⁻⁶, so a milligram is a thousand micrograms for every substance there is. 1 mg is 1,000 mcg, 5 mg is 5,000 mcg, 10 mg is 10,000 mcg, and 0.1 mg is 100 mcg. Nothing about the peptide, the vial or the diluent changes it.

Is 0.25 mg the same as 250 mcg?

Yes — identical amounts written two ways. 0.25 × 1,000 = 250, so a vial label reading 0.25 mg and a protocol sheet reading 250 mcg are describing the same mass of drug. The same pairing holds all the way up and down: 0.1 mg = 100 mcg, 0.5 mg = 500 mcg, 1 mg = 1,000 mcg, 2.5 mg = 2,500 mcg. If two sources you trust seem to disagree by a factor of a thousand, check whether they are simply using different units before assuming one is wrong.

How do I convert mcg to units on an insulin syringe?

You need the concentration, because a unit is a volume and not a mass. Multiply the concentration in mg/mL by 1000 to get mcg/mL, divide by 100 because a U-100 barrel is 100 units per mL, and that gives micrograms per unit mark; your dose in mcg divided by that figure is the number of units. At 2.5 mg/mL a mark is 25 mcg, so 250 mcg is 10 units. At 5 mg/mL a mark is 50 mcg and the same 250 mcg is 5 units.

How many mcg is 1 unit on a U-100 syringe?

There is no single answer — it depends entirely on what is dissolved in the barrel. One unit is 0.01 mL, so at 1 mg/mL it carries 10 mcg, at 2 mg/mL 20 mcg, at 2.5 mg/mL 25 mcg, at 5 mg/mL 50 mcg and at 10 mg/mL 100 mcg. Anyone who quotes "units" for a peptide without naming a concentration has not given you enough information to draw anything, and the number cannot be guessed from the syringe.

I drew 10 units — how many mcg did I take?

Multiply the unit marks by the micrograms one mark is worth. At 1 mg/mL, 10 units is 100 mcg; at 2.5 mg/mL it is 250 mcg; at 5 mg/mL it is 500 mcg; at 10 mg/mL it is 1,000 mcg, which is 1 mg. The third chart on this page reads that direction across six concentrations. This is exact arithmetic, not an estimate — the quarter-unit rounding only applies when you are placing a dose onto a barrel, not when you are reading one off it.

Why is my vial labelled in mg but my dose quoted in mcg?

Because each unit is chosen to make its own number convenient, and neither is more correct. A lyophilised vial holds a few milligrams of powder, so milligrams is the tidy way to print it; a dose is a small fraction of that vial, so micrograms is the tidy way to quote it. Approved products do both: the EGRIFTA WR label states a dose of 1.28 mg, while the Sandostatin label states strengths of "50 mcg/mL, 100 mcg/mL, or 500 mcg/mL". Both are peptides. The rule that protects you is to convert once, at the start, and then do the rest of the arithmetic in a single unit.

What actually happens if I mix up mcg and mg?

The dose changes by a factor of 1,000 in whichever direction the mistake went, and nothing on the syringe reveals it. A 250 mcg dose read as 250 mg is 250,000 mcg, which is 50 whole 5 mg vials of powder — more than could be drawn from one vial at all, which is the only thing that makes that direction partly self-limiting. The opposite slip, reading a milligram figure as micrograms, quietly delivers a thousandth of what was intended and looks like a drug that does not work. This page will not tell you how often either happens: the two standard references on the confusion are behind servers that refuse automated retrieval, and we do not cite what we have not read.

How much of this peptide should I inject?

This page will not say, and the reason is that for most of these compounds there is no sourceable answer to give. No approved label, no dose-ranging trial, nothing a regulator has reviewed — FDA has put BPC-157, ipamorelin acetate, kisspeptin-10, CJC-1295, AOD-9604 and others in category 2 of its compounding bulks review, the list of substances that "may present significant safety risks", and of BPC-157 it states that it "lacks sufficient information to know whether the drug would cause harm when administered to humans". A number invented to fill that gap would look exactly like a real one on a page like this. This tool converts a figure you were already given; it does not produce one.

Does the concentration change how much drug is in the vial?

No. A 5 mg vial holds 5,000 mcg whether it is reconstituted to 1 mg/mL or 10 mg/mL — the water adds volume, not drug. What changes is the size of the draw for a given dose. 500 mcg is 50 units at 1 mg/mL, 20 units at 2.5 mg/mL and 5 units at 10 mg/mL. A weaker concentration makes each mark worth less and the draw longer, which is easier to read accurately; a stronger one is the only option once a draw would exceed the 100 units a 1 mL barrel holds.

Arithmetic only — no dosing protocol

Peptide mcg to mg Converter

Micrograms, milligrams and syringe units, converted in any direction. The mcg-to-mg half needs no vial and no syringe — it is one division by a thousand.

Reviewed by: Alpha Health Finder Editorial Team
Last reviewed: September 2026

One factor of a thousand, and where it hides

Micrograms to milligrams is not a clinical calculation. It is the SI prefix system and nothing else: NIST lists milli as "10⁻³" and micro as "10⁻⁶", so a milligram is a thousand micrograms and the conversion is a single division that does not care what is dissolved in the vial, how much water went in, or whether there is a syringe in the room at all. 1 mg is 1,000 mcg. 0.25 mg is 250 mcg. 0.5 mg is 500 mcg. That is the whole of it, and it is the half of this page that works with no other information.

The trouble is that a peptide is routinely described in both units within the same sentence, and neither is wrong. The unit is a labelling convention, not a property of the molecule. EGRIFTA WR, an approved tesamorelin product, states its dose in milligrams — "One dose of EGRIFTA WR is 1.28 mg in 0.16 mL of the reconstituted solution." Sandostatin, an approved octreotide product, states its strengths in micrograms — "Injection: 50 mcg/mL, 100 mcg/mL, or 500 mcg/mL of octreotide (as acetate) as a clear solution in a single-dose ampul." Both are peptides. Both labels are correct. A lyophilised vial almost always carries milligrams because the mass in it is a convenient number of them, and a dose drawn out of it is almost always quoted in micrograms for the same reason. The gap between the two is where the factor of a thousand lives.

The third unit only appears once there is a syringe. A U-100 insulin barrel is graduated so that 100 units is exactly 1 mL — that is the definition of U-100, printed on the products it is defined by: the Humulin R carton reads "100 units per mL (U-100)" and "Use only with a U-100 syringe". So one unit mark is 0.01 mL, and what that mark is worth in micrograms depends entirely on the concentration of what is in the barrel. At 2.5 mg/mL a mark carries 25 mcg; at 10 mg/mL the same mark carries 100 mcg. Nothing on the barrel tells you which, which is why this converter asks for the concentration rather than assuming one.

Now the size of the slip, stated as arithmetic because arithmetic is the part that can be stood behind. Read a 250 mcg dose as 250 mg and you have not made a small error: 250 mg is 250,000 mcg, which is 50 entire 5 mg vials of powder. The mistake is self-limiting in the sense that the drug to commit it with does not physically exist in one vial — but it is not self-limiting at the other end of the scale, and it is completely invisible on a syringe barrel, which is numbered in units and says nothing about mass. What this page will NOT tell you is how often that actually happens to people. The two standard references on the confusion — ISMP's error-prone abbreviations list and the Joint Commission's Do Not Use list — both sit behind servers that refuse automated retrieval, and this site does not cite a document it has not opened. So there is no incidence figure here, and the absence is deliberate rather than an oversight.

There is also no dose here, for any compound. Most of the peptides people arrive holding have no approved label and no dose-ranging trial to derive one from. FDA has placed a long list of them — BPC-157, ipamorelin acetate, kisspeptin-10, CJC-1295, AOD-9604, TB-500 and others — in category 2 of its compounding bulks review, which it describes as the substances that "may present significant safety risks", and of BPC-157 it writes: "FDA has identified no, or only limited, safety-related information for the proposed routes of administration. Therefore, the agency lacks sufficient information to know whether the drug would cause harm when administered to humans." A directory that printed a milligram figure into that gap would be inventing one, and an invented number is indistinguishable from a real one once it is on a page. Bring the figure a clinician gave you; this converts it.

If you do not yet know your concentration — the vial is dry, or you know only the milligrams on it and the water you intend to add — that is a different calculation, and the peptide reconstitution calculator solves it. This page assumes you already have the concentration, or that you only need the mcg-to-mg half and have no syringe in the picture at all.

The formula

milligrams = micrograms ÷ 1000

micrograms = milligrams × 1000

mcg per unit mark = concentration (mg/mL) × 1000 ÷ 100

units to draw = dose (mcg) ÷ mcg per unit mark

mcg in the mark = units drawn × mcg per unit mark

The first two lines are the SI prefix definition and need no vial, no diluent and no syringe. The 1000 is micrograms per milligram; the 100 is units per millilitre, which is what U-100 means and not a figure to be looked up. Units are rounded to the quarter mark for display — a quarter unit is not a printed line on any barrel we could source a specification for, it is the finest gap anyone can reasonably judge between lines, so where a dose does not land on a mark the tables show what the reachable mark actually delivers instead of echoing the dose back.

Worked example

EGRIFTA WR, an FDA-approved lyophilised peptide, run through all three units — an 11.6 mg vial reconstituted with 1.3 mL, labelled 8 mg per mL, dose 1.28 mg:

1.28 mg × 1000 = 1,280 mcg — the same dose, written the way a peptide dose is usually quoted
8 mg/mL × 1000 ÷ 100 = 80 mcg in one unit mark
1,280 mcg ÷ 80 mcg = 16 units
16 ÷ 100 = 0.16 mL — the volume the label itself states
Backwards, as a check: 16 units × 80 mcg = 1,280 mcg = 1.28 mg
The label's Instructions for Use tell the patient to "Adjust the plunger to reach exactly the 16 mark (0.16 mL)". The converter and the regulator land on the same mark.
Use the label's 8 mg/mL, not 11.6 ÷ 1.3 = 8.92 mg/mL — the vial is overfilled so the stated concentration is reliably deliverable, and the nominal figure would put you on 14.25 units instead of 16
And the slip, for scale: read 1,280 mcg as 1,280 mg and the dose becomes 1,280,000 mcg — more than 110 whole 11.6 mg vials

Micrograms to milligrams, and what the decimal slip costs

The conversion itself needs no vial and no syringe. The right-hand columns are the same digits read in the wrong unit, so the size of that mistake is on the page rather than left to imagination.

Dose in mcg	In milligrams÷ 1000	Read as mg by mistakethe same digits	That much powderwhole 5 mg vials
25 mcg	0.025 mg	25 mg= 25,000 mcg	5 vials
50 mcg	0.05 mg	50 mg= 50,000 mcg	10 vials
100 mcg	0.1 mg	100 mg= 100,000 mcg	20 vials
125 mcg	0.125 mg	125 mg= 125,000 mcg	25 vials
150 mcg	0.15 mg	150 mg= 150,000 mcg	30 vials
200 mcg	0.2 mg	200 mg= 200,000 mcg	40 vials
250 mcg	0.25 mg	250 mg= 250,000 mcg	50 vials
300 mcg	0.3 mg	300 mg= 300,000 mcg	60 vials
500 mcg	0.5 mg	500 mg= 500,000 mcg	100 vials
600 mcg	0.6 mg	600 mg= 600,000 mcg	120 vials
750 mcg	0.75 mg	750 mg= 750,000 mcg	150 vials
1,000 mcg	1 mg	1,000 mg= 1,000,000 mcg	200 vials
1,500 mcg	1.5 mg	1,500 mg= 1,500,000 mcg	300 vials
2,000 mcg	2 mg	2,000 mg= 2,000,000 mcg	400 vials
2,500 mcg	2.5 mg	2,500 mg= 2,500,000 mcg	500 vials
5,000 mcg	5 mg	5,000 mg= 5,000,000 mcg	1,000 vials
10,000 mcg	10 mg	10,000 mg= 10,000,000 mcg	2,000 vials

Read down the first column until you find the figure you were given; the answer is one cell to the right. The two columns after it are the same row misread by a factor of 1000: a 1,000 mcg dose is a fifth of one 5 mg vial, while a 1,000 mg dose is 200 of them. Nothing on a syringe barrel distinguishes the two, because a barrel is numbered in volume and says nothing about mass.

Micrograms and milligrams to units on a U-100 syringe

Read down for the dose you were given, across for the concentration in the barrel. The figure is unit marks on a U-100 insulin syringe; the milligram equivalent of each dose is under the row label.

Dose	1 mg/mL10 mcg per unit	2 mg/mL20 mcg per unit	2.5 mg/mL25 mcg per unit	5 mg/mL50 mcg per unit	8 mg/mL80 mcg per unit	10 mg/mL100 mcg per unit
50 mcg0.05 mg	5 units0.05 mL	2.5 units0.025 mL	2 units0.02 mL	1 unit0.01 mL	0.75 units0.0075 mL → 60 mcg	0.5 units0.005 mL
100 mcg0.1 mg	10 units0.1 mL	5 units0.05 mL	4 units0.04 mL	2 units0.02 mL	1.25 units0.0125 mL	1 unit0.01 mL
125 mcg0.125 mg	12.5 units0.125 mL	6.25 units0.0625 mL	5 units0.05 mL	2.5 units0.025 mL	1.5 units0.015 mL → 120 mcg	1.25 units0.0125 mL
200 mcg0.2 mg	20 units0.2 mL	10 units0.1 mL	8 units0.08 mL	4 units0.04 mL	2.5 units0.025 mL	2 units0.02 mL
250 mcg0.25 mg	25 units0.25 mL	12.5 units0.125 mL	10 units0.1 mL	5 units0.05 mL	3.25 units0.0325 mL → 260 mcg	2.5 units0.025 mL
300 mcg0.3 mg	30 units0.3 mL	15 units0.15 mL	12 units0.12 mL	6 units0.06 mL	3.75 units0.0375 mL	3 units0.03 mL
500 mcg0.5 mg	50 units0.5 mL	25 units0.25 mL	20 units0.2 mL	10 units0.1 mL	6.25 units0.0625 mL	5 units0.05 mL
600 mcg0.6 mg	60 units0.6 mL	30 units0.3 mL	24 units0.24 mL	12 units0.12 mL	7.5 units0.075 mL	6 units0.06 mL
750 mcg0.75 mg	75 units0.75 mL	37.5 units0.375 mL	30 units0.3 mL	15 units0.15 mL	9.5 units0.095 mL → 760 mcg	7.5 units0.075 mL
1,000 mcg1 mg	100 units1 mL	50 units0.5 mL	40 units0.4 mL	20 units0.2 mL	12.5 units0.125 mL	10 units0.1 mL
1,280 mcg1.28 mg	128 units1.28 mL — over a 1 mL barrel	64 units0.64 mL	51.25 units0.5125 mL → 1,281.25 mcg	25.5 units0.255 mL → 1,275 mcg	16 units0.16 mL	12.75 units0.1275 mL → 1,275 mcg
1,500 mcg1.5 mg	150 units1.5 mL — over a 1 mL barrel	75 units0.75 mL	60 units0.6 mL	30 units0.3 mL	18.75 units0.1875 mL	15 units0.15 mL
2,000 mcg2 mg	200 units2 mL — over a 1 mL barrel	100 units1 mL	80 units0.8 mL	40 units0.4 mL	25 units0.25 mL	20 units0.2 mL
2,500 mcg2.5 mg	250 units2.5 mL — over a 1 mL barrel	125 units1.25 mL — over a 1 mL barrel	100 units1 mL	50 units0.5 mL	31.25 units0.3125 mL	25 units0.25 mL
3,000 mcg3 mg	300 units3 mL — over a 1 mL barrel	150 units1.5 mL — over a 1 mL barrel	120 units1.2 mL — over a 1 mL barrel	60 units0.6 mL	37.5 units0.375 mL	30 units0.3 mL
5,000 mcg5 mg	500 units5 mL — over a 1 mL barrel	250 units2.5 mL — over a 1 mL barrel	200 units2 mL — over a 1 mL barrel	100 units1 mL	62.5 units0.625 mL	50 units0.5 mL

Where a second microgram figure appears, the dose does not land on a mark and that is what the nearest quarter unit actually delivers. Where a cell says it is over a 1 mL barrel, no insulin syringe holds the draw: 100 units is 1 mL and that is the whole barrel. Every cell here comes from the same function the converter above calls.

Units already drawn, back to micrograms

The reverse read, for the question that gets asked after the injection rather than before it. Find the mark you drew to and the concentration in the barrel; the cell is what was in the syringe.

Units drawn	1 mg/mL10 mcg per unit	2 mg/mL20 mcg per unit	2.5 mg/mL25 mcg per unit	5 mg/mL50 mcg per unit	8 mg/mL80 mcg per unit	10 mg/mL100 mcg per unit
1 unit0.01 mL	10 mcg0.01 mg	20 mcg0.02 mg	25 mcg0.025 mg	50 mcg0.05 mg	80 mcg0.08 mg	100 mcg0.1 mg
2 units0.02 mL	20 mcg0.02 mg	40 mcg0.04 mg	50 mcg0.05 mg	100 mcg0.1 mg	160 mcg0.16 mg	200 mcg0.2 mg
2.5 units0.025 mL	25 mcg0.025 mg	50 mcg0.05 mg	62.5 mcg0.0625 mg	125 mcg0.125 mg	200 mcg0.2 mg	250 mcg0.25 mg
4 units0.04 mL	40 mcg0.04 mg	80 mcg0.08 mg	100 mcg0.1 mg	200 mcg0.2 mg	320 mcg0.32 mg	400 mcg0.4 mg
5 units0.05 mL	50 mcg0.05 mg	100 mcg0.1 mg	125 mcg0.125 mg	250 mcg0.25 mg	400 mcg0.4 mg	500 mcg0.5 mg
6 units0.06 mL	60 mcg0.06 mg	120 mcg0.12 mg	150 mcg0.15 mg	300 mcg0.3 mg	480 mcg0.48 mg	600 mcg0.6 mg
8 units0.08 mL	80 mcg0.08 mg	160 mcg0.16 mg	200 mcg0.2 mg	400 mcg0.4 mg	640 mcg0.64 mg	800 mcg0.8 mg
10 units0.1 mL	100 mcg0.1 mg	200 mcg0.2 mg	250 mcg0.25 mg	500 mcg0.5 mg	800 mcg0.8 mg	1,000 mcg1 mg
12 units0.12 mL	120 mcg0.12 mg	240 mcg0.24 mg	300 mcg0.3 mg	600 mcg0.6 mg	960 mcg0.96 mg	1,200 mcg1.2 mg
15 units0.15 mL	150 mcg0.15 mg	300 mcg0.3 mg	375 mcg0.375 mg	750 mcg0.75 mg	1,200 mcg1.2 mg	1,500 mcg1.5 mg
16 units0.16 mL	160 mcg0.16 mg	320 mcg0.32 mg	400 mcg0.4 mg	800 mcg0.8 mg	1,280 mcg1.28 mg	1,600 mcg1.6 mg
20 units0.2 mL	200 mcg0.2 mg	400 mcg0.4 mg	500 mcg0.5 mg	1,000 mcg1 mg	1,600 mcg1.6 mg	2,000 mcg2 mg
25 units0.25 mL	250 mcg0.25 mg	500 mcg0.5 mg	625 mcg0.625 mg	1,250 mcg1.25 mg	2,000 mcg2 mg	2,500 mcg2.5 mg
30 units0.3 mL	300 mcg0.3 mg	600 mcg0.6 mg	750 mcg0.75 mg	1,500 mcg1.5 mg	2,400 mcg2.4 mg	3,000 mcg3 mg
40 units0.4 mL	400 mcg0.4 mg	800 mcg0.8 mg	1,000 mcg1 mg	2,000 mcg2 mg	3,200 mcg3.2 mg	4,000 mcg4 mg
50 units0.5 mL	500 mcg0.5 mg	1,000 mcg1 mg	1,250 mcg1.25 mg	2,500 mcg2.5 mg	4,000 mcg4 mg	5,000 mcg5 mg
75 units0.75 mL	750 mcg0.75 mg	1,500 mcg1.5 mg	1,875 mcg1.875 mg	3,750 mcg3.75 mg	6,000 mcg6 mg	7,500 mcg7.5 mg
100 units1 mL	1,000 mcg1 mg	2,000 mcg2 mg	2,500 mcg2.5 mg	5,000 mcg5 mg	8,000 mcg8 mg	10,000 mcg10 mg

One row of this table is checkable against an FDA label rather than against us: 16 units at 8 mg/mL is 1,280 mcg, and the EGRIFTA WR label states its dose as 1.28 mg in 0.16 mL and sends the patient to the 16 mark. Everything in this table is a multiplication, so it is exact — the quarter-unit rounding only applies going the other way, when a dose has to be placed on a barrel.

Frequently asked questions

How many mcg are in a mg?: Exactly 1,000, by definition rather than by measurement — NIST lists the SI prefix milli as 10⁻³ and micro as 10⁻⁶, so a milligram is a thousand micrograms for every substance there is. 1 mg is 1,000 mcg, 5 mg is 5,000 mcg, 10 mg is 10,000 mcg, and 0.1 mg is 100 mcg. Nothing about the peptide, the vial or the diluent changes it.
Is 0.25 mg the same as 250 mcg?: Yes — identical amounts written two ways. 0.25 × 1,000 = 250, so a vial label reading 0.25 mg and a protocol sheet reading 250 mcg are describing the same mass of drug. The same pairing holds all the way up and down: 0.1 mg = 100 mcg, 0.5 mg = 500 mcg, 1 mg = 1,000 mcg, 2.5 mg = 2,500 mcg. If two sources you trust seem to disagree by a factor of a thousand, check whether they are simply using different units before assuming one is wrong.
How do I convert mcg to units on an insulin syringe?: You need the concentration, because a unit is a volume and not a mass. Multiply the concentration in mg/mL by 1000 to get mcg/mL, divide by 100 because a U-100 barrel is 100 units per mL, and that gives micrograms per unit mark; your dose in mcg divided by that figure is the number of units. At 2.5 mg/mL a mark is 25 mcg, so 250 mcg is 10 units. At 5 mg/mL a mark is 50 mcg and the same 250 mcg is 5 units.
How many mcg is 1 unit on a U-100 syringe?: There is no single answer — it depends entirely on what is dissolved in the barrel. One unit is 0.01 mL, so at 1 mg/mL it carries 10 mcg, at 2 mg/mL 20 mcg, at 2.5 mg/mL 25 mcg, at 5 mg/mL 50 mcg and at 10 mg/mL 100 mcg. Anyone who quotes "units" for a peptide without naming a concentration has not given you enough information to draw anything, and the number cannot be guessed from the syringe.
I drew 10 units — how many mcg did I take?: Multiply the unit marks by the micrograms one mark is worth. At 1 mg/mL, 10 units is 100 mcg; at 2.5 mg/mL it is 250 mcg; at 5 mg/mL it is 500 mcg; at 10 mg/mL it is 1,000 mcg, which is 1 mg. The third chart on this page reads that direction across six concentrations. This is exact arithmetic, not an estimate — the quarter-unit rounding only applies when you are placing a dose onto a barrel, not when you are reading one off it.
Why is my vial labelled in mg but my dose quoted in mcg?: Because each unit is chosen to make its own number convenient, and neither is more correct. A lyophilised vial holds a few milligrams of powder, so milligrams is the tidy way to print it; a dose is a small fraction of that vial, so micrograms is the tidy way to quote it. Approved products do both: the EGRIFTA WR label states a dose of 1.28 mg, while the Sandostatin label states strengths of "50 mcg/mL, 100 mcg/mL, or 500 mcg/mL". Both are peptides. The rule that protects you is to convert once, at the start, and then do the rest of the arithmetic in a single unit.
What actually happens if I mix up mcg and mg?: The dose changes by a factor of 1,000 in whichever direction the mistake went, and nothing on the syringe reveals it. A 250 mcg dose read as 250 mg is 250,000 mcg, which is 50 whole 5 mg vials of powder — more than could be drawn from one vial at all, which is the only thing that makes that direction partly self-limiting. The opposite slip, reading a milligram figure as micrograms, quietly delivers a thousandth of what was intended and looks like a drug that does not work. This page will not tell you how often either happens: the two standard references on the confusion are behind servers that refuse automated retrieval, and we do not cite what we have not read.
How much of this peptide should I inject?: This page will not say, and the reason is that for most of these compounds there is no sourceable answer to give. No approved label, no dose-ranging trial, nothing a regulator has reviewed — FDA has put BPC-157, ipamorelin acetate, kisspeptin-10, CJC-1295, AOD-9604 and others in category 2 of its compounding bulks review, the list of substances that "may present significant safety risks", and of BPC-157 it states that it "lacks sufficient information to know whether the drug would cause harm when administered to humans". A number invented to fill that gap would look exactly like a real one on a page like this. This tool converts a figure you were already given; it does not produce one.
Does the concentration change how much drug is in the vial?: No. A 5 mg vial holds 5,000 mcg whether it is reconstituted to 1 mg/mL or 10 mg/mL — the water adds volume, not drug. What changes is the size of the draw for a given dose. 500 mcg is 50 units at 1 mg/mL, 20 units at 2.5 mg/mL and 5 units at 10 mg/mL. A weaker concentration makes each mark worth less and the draw longer, which is easier to read accurately; a stronger one is the only option once a draw would exceed the 100 units a 1 mL barrel holds.

Sources

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Next steps

Do not know your concentration yet?If all you have is the milligrams on the vial and the water you plan to add, the reconstitution calculator works out the concentration first and then the mark.Compare peptide therapy providersClinician-supervised platforms that supply the vial and a written instruction in one unit, rather than leaving you to reconcile a milligram label with a microgram protocol.

Related calculators

Educational reference, not medical advice. Unit conversion only. This tool does not recommend a dose, a frequency or a cycle for any peptide, and for most research peptides no sourceable dose exists. It also does not state how often mcg/mg confusion causes harm, because the standard references on that could not be retrieved and verified. Any decision about what to inject belongs to a prescribing clinician.