Price per mg explained

A 5 mg vial for one price and a 10 mg vial for another are hard to compare at a glance. Price per mg puts both on one scale: what you pay for each milligram the listing says is in the vial.

The formula

Two steps, always in this order:

• Unit price = pack price ÷ number of units in the pack.
• Price per mg = unit price ÷ strength of one unit, in mg.

Prices are euros including VAT, so every shop starts from the same basis. How that works is covered in the VAT and shipping guide.

Worked examples

The numbers below are made up to show the arithmetic. They are not live prices.

• Example A: a 5 mg vial at €20.00 is €4.00 per mg.
• Example B: a 10 mg vial at €32.00 is €3.20 per mg.
• Example C: a pack of 3 vials of 10 mg at €84.00 has a unit price of €28.00 (84 ÷ 3), which is €2.80 per mg.

In this example the 10 mg vial is cheaper per mg than the 5 mg vial, even though it costs more in total. The pack is cheaper per mg again, but you pay €84.00 at once.

What “lowest” means here

The lowest price on a compound page follows three rules.

• Only offers that are in stock can be the lowest. Sold-out offers stay visible and greyed out.
• “Lowest” is the cheapest single unit. A pack is compared per unit and can carry a “Best per unit” hint, but it does not take the “Lowest” label while a single unit is on offer.
• The headline “lowest price per mg” on a compound page uses single units. Packs only count for a compound that no shop sells singly.

The reason is fairness. A shop that only sells packs and a shop that sells single vials are not in the same position: one asks you to spend more at once. Keeping singles apart from packs avoids ranking those two against each other as if they offered the same thing.

How we read the strength

The strength comes from the shop’s own listing, mostly the product name or the variant label. We read:

• “10 mg” as 10 mg, and “500 mcg” as 0.5 mg.
• “3 × 30 mg” as 3 units of 30 mg each.
• “5 + 5 mg” as 10 mg in total.

Volumes (ml) and international units (IU) are not converted to mg. Offers whose strength is given in ml or IU, or not at all, are listed but get no per-mg price.

Where per mg is not shown

Per mg is left out for oral products, nasal sprays and topical products. A “unit” there can be a bottle of 100 tablets or a 15 mL bottle, so dividing by milligrams would give a number that looks precise and means little. Those offers are compared by unit price instead.

Limits of the number

• Same compound, same form. Compare per-mg prices of one compound only. Different compounds have different molecular masses, so a lower price per mg for one compound says nothing about another.
• Total spend still counts. The lowest price per mg is often a larger vial or a pack. Whether that suits you is your call.
• The strength is the shop’s statement. We do not test what is in a vial. If a listing is wrong, our figure is wrong too. Check the listing before you order.
• Shipping is not included. Two shops with the same price per mg can end up with different totals at checkout.

A price per mg is a way to sort offers. It is not a measure of quality, purity or suitability for any purpose.