Researcher’s Guide:
Understanding Quantities
What the number on the vial means, how it relates to concentration, and how far a vial actually goes.
The number on the vial is a mass, not a strength
A vial marked 10 mg contains ten milligrams of peptide. That is the entire quantity — not a concentration, not a per-measure amount, and not something that changes when you add water. It is simply how much material is sitting in the bottom of the vial as a freeze-dried solid.
This is the single most useful thing to understand about quantities, because everything else follows from it. Crown Peptides supplies research peptides for laboratory research use only; they are not intended for human consumption or therapeutic use. What follows is simple maths, nothing more.
Milligrams and micrograms
Two units, one relationship, and the source of most quantity confusion.
Milligram (mg)
How vials are labelled. Most research peptides are supplied in single or double-digit milligram quantities, which is why you see 5 mg, 10 mg and 20 mg on the label.
- 1 mg equals
- 1000 mcg
- Typical vial
- 5–100 mg
- Used for
- Vial contents
Microgram (mcg)
How individual measures are usually expressed. A microgram is one thousandth of a milligram, so quantities that look tiny in mg become readable numbers in mcg.
- 1000 mcg equals
- 1 mg
- 0.25 mg equals
- 250 mcg
- Used for
- Measured amounts
Where concentration comes from
The vial sets the total. You set the concentration, by choosing how much water to add.
Reconstitution does not create or destroy peptide. A 10 mg vial holds 10 mg whether you add one millilitre of bacteriostatic water or five. What changes is how tightly that material is packed into the liquid — and therefore how much liquid you draw to measure any given amount.
Concentration is simply the vial strength divided by the water added. Ten milligrams in two millilitres gives five milligrams per millilitre. The same vial in one millilitre gives ten. More water means a weaker solution and larger, easier-to-measure volumes; less water means a stronger solution and very small volumes.
| Vial | Water added | Concentration | 250 mcg measures as |
|---|---|---|---|
| 5 mg | 1 mL | 5 mg/mL | 0.05 mL — 5 units |
| 5 mg | 2 mL | 2.5 mg/mL | 0.1 mL — 10 units |
| 10 mg | 1 mL | 10 mg/mL | 0.025 mL — 2.5 units |
| 10 mg | 2 mL | 5 mg/mL | 0.05 mL — 5 units |
| 20 mg | 2 mL | 10 mg/mL | 0.025 mL — 2.5 units |
| 50 mg | 2.5 mL | 20 mg/mL | 0.0125 mL — 1.25 units |
How far a vial goes
This one is pure division, and it does not depend on how much water you used.
Start with the total in the vial
Take the labelled strength and convert it to micrograms if that is easier to work with. A 10 mg vial is 10,000 mcg.
Divide by the amount you are measuring out
At 250 mcg per measure, 10,000 divided by 250 gives forty measures from that vial. At 500 mcg it gives twenty. The water you added never enters this calculation.
Check it against the usable window
A vial that yields forty measures is only useful if the solution stays good for that long. Reconstituted peptide keeps for roughly 28 days refrigerated, so it is worth reconciling the number of measures against the time available.
Work backwards if the volumes are awkward
If a measure works out at under one syringe unit it is hard to draw accurately. Adding more water spreads the same material across a larger volume and makes each measure easier to read, without changing how many you get.
Vials, blends and bundles
A blend vial lists more than one figure, such as 5 mg / 5 mg. That means each compound is present at that quantity — a 5 mg / 5 mg vial holds five milligrams of each, ten milligrams of material in total. Reconstitute it once and both compounds share the same water, so both concentrations follow from the same division.
Bundles work differently again. A listing described as 10 mg × 5 vials is five separate vials of ten milligrams each, not a single fifty milligram vial. They are reconstituted individually as you need them, which is part of the appeal — the unopened vials keep their much longer dry shelf life while you work through the first.
Multi-peptide bundles list each compound by name, and every vial inside carries its own labelled quantity and batch certificate, exactly as a single vial would.
Three numbers worth writing down
Almost every quantity question comes back to one of these. Note them on the vial when you reconstitute and the sums stop being something you have to redo.
Vial strength
The total mass supplied, printed on the label. Fixed, and unaffected by anything you do afterwards.
Water added
Your choice, and the only variable that sets concentration. Worth recording, because nothing on the vial tells you afterwards.
Date reconstituted
Not a quantity, but it decides how much of that vial you can realistically use before the solution is past its window.
Let the calculator do the division
Every figure on this page comes from the same three inputs. Enter your vial strength, the water you added and the amount you want, and the calculator returns the concentration, the volume and the syringe units without the mental maths.
Provided for laboratory research reference. Figures shown are worked examples of the underlying maths and are not batch-specific commitments.
Work it out in seconds
The calculator turns vial strength and reconstitution volume into millilitres and syringe units.
See also Storage Information and our Lab Reports.
