A peptide vial costs what you paid divided by the milligrams of peptide actually in it — not by the number on the label. Purity and fill weight both cut what you receive while the price stays the same, so a cheaper vial at 70% purity often costs more per milligram than a dearer one at 99%.
Last updated 2026-10-09 · By the OzPeptides lab team · Free, no sign-up
Column A is $0.36 per milligram cheaper on the peptide actually in the vial — 3% less — even though column B is the cheaper vial to buy.
Purity here is whatever the vial claims. A stated figure with no certificate behind it is a marketing number, not a measurement — and the arithmetic above is only as good as the figure you put into it.
A vial has two numbers that decide what you actually receive, and the price tag reflects neither. The first is purity: the proportion of the material that is the peptide you wanted rather than truncated sequences, deletion products, residual reagents or salt. The second is fill weight: how many milligrams are in the glass, which is a separate question from how pure those milligrams are.
Both reduce what arrives while leaving the price alone, and they multiply rather than add. A vial labelled 10mg that is 70% pure holds 7mg of peptide. If the same vial is also underfilled and assays at 8.4mg, it holds 5.88mg. The label still says 10mg and the invoice still says $60.
This is why cheaper vials so often are not. The comparison people make is price against price, because that is the comparison the listing invites. The comparison that decides value is price against milligrams of peptide, and it frequently reverses the order.
Take two vials. The first costs $60 with $25 shipping, is labelled 10mg, and states 70% purity. The second costs $160 with $15 shipping, is labelled 15mg, and states 99%. On sticker price the first is less than half the second.
The first delivers 7mg for $85, which is $12.14 per milligram of peptide. The second delivers 14.85mg for $175, which is $11.78. The dearer vial is cheaper on what you came for, and that is before considering that one of those purity figures has a certificate behind it and the other may not.
The arithmetic is not always in favour of the higher price, and it should not be. A genuinely 95% pure, correctly filled, cheaper vial wins this calculation — which is the reason to run it rather than assume. What the calculation removes is the ability to compare on sticker price alone and call it a saving.
Every input above is only as reliable as its source. A purity claim becomes a measurement when a certificate of analysis names the batch, the method, the instrument and the date, and when that certificate corresponds to the vial in your hand rather than to a batch from a year ago.
Absent that, there is nothing to put into the calculation. "High purity", "pharmaceutical grade" and "99%+" with no document behind them are all the same input: unknown. Treating unknown as 99% is the assumption that makes a cheap vial look cheap, and it is the assumption the price is relying on.
This is also why fill weight is worth asking about separately. Purity is the figure sellers quote, because it is the flattering one; content against label is the figure that is quietly more often wrong, and it is only visible if someone has weighed or assayed the vial.
There are no suppliers named here and no claims made about anyone else's product. Both columns are empty until you fill them in, and the only figure supplied is our own list price, as a starting point you can overwrite.
That is deliberate. A comparison worth trusting is one the reader performs with their own numbers, and a claim about a competitor's contents would need test data on those specific vials to stand behind. The arithmetic needs no such claim: it works on whatever figures the sellers themselves publish.
Divide what you paid by the milligrams of peptide actually in the vial, not by the number on the label. A $60 vial labelled 10mg at 70% purity holds 7mg, so it costs $8.57 per milligram. A $160 vial labelled 15mg at 99% holds 14.85mg, which is $10.77 per milligram — closer than the sticker prices suggest, and the gap narrows further once shipping is counted.
Because purity and fill weight both reduce what you receive while the price stays the same. At 70% purity you are paying for 30% of something that is not the peptide. If the vial is also underfilled, the two effects multiply: a 10mg label that assays at 8.4mg and 70% pure holds 5.88mg, so a $60 vial is $10.20 per real milligram.
It means whatever the seller has written down. A purity figure is only a measurement if a certificate of analysis backs it, naming the method, the instrument and the batch. Without that it is a marketing number, and the arithmetic on this page is only as good as the figure you put into it.
Not usually. HPLC purity is the proportion of the peptide-related material that is the target peptide, which is a different question from how much of the vial contents are peptide at all. A vial can be 99% pure by HPLC and still be underfilled, which is why fill weight is a separate input here.
Yes, if you are comparing what leaves your account. Shipping is a per-order cost rather than a per-vial one, so it matters most on single-vial orders and least on large ones. The calculator takes it per vial so the two columns stay comparable.
That is what the calculation answers, and sometimes the answer is no. If a cheaper vial is genuinely 95% pure and correctly filled, it can win on cost per milligram. The point of the arithmetic is that the comparison is decidable rather than a matter of belief.
Peptides synthesised and tested to a documented specification are typically released at 98% or better by HPLC. Figures below that are not automatically a problem — it depends what the material is for — but they change the price per milligram, and an absent figure changes nothing because there is nothing to put in the sum.
No. It compares cost. These are laboratory research compounds and no page on this site gives dosing guidance.
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